WorldWideScience

Sample records for dft based computational

  1. VLSI Architectures for Computing DFT's

    Science.gov (United States)

    Truong, T. K.; Chang, J. J.; Hsu, I. S.; Reed, I. S.; Pei, D. Y.

    1986-01-01

    Simplifications result from use of residue Fermat number systems. System of finite arithmetic over residue Fermat number systems enables calculation of discrete Fourier transform (DFT) of series of complex numbers with reduced number of multiplications. Computer architectures based on approach suitable for design of very-large-scale integrated (VLSI) circuits for computing DFT's. General approach not limited to DFT's; Applicable to decoding of error-correcting codes and other transform calculations. System readily implemented in VLSI.

  2. Computational study of AuSin (n=1-9) nanoalloy clusters invoking DFT based descriptors

    Science.gov (United States)

    Ranjan, Prabhat; Kumar, Ajay; Chakraborty, Tanmoy

    2016-04-01

    Nanoalloy clusters formed between Au and Si are topics of great interest today from both scientific and technological point of view. Due to its remarkable catalytic, electronic, mechanical and magnetic properties Au-Si nanoalloy clusters have extensive applications in the field of microelectronics, catalysis, biomedicine, and jewelry industry. Density Functional Theory (DFT) is a new paradigm of quantum mechanics, which is very much popular to study the electronic properties of materials. Conceptual DFT based descriptors have been invoked to correlate the experimental properties of nanoalloy clusters. In this venture, we have systematically investigated AuSin (n=1-9) nanoalloy clusters in the theoretical frame of the B3LYP exchange correlation. The experimental properties of AuSin (n=1-9) nanoalloy clusters are correlated in terms of DFT based descriptors viz. HOMO-LUMO gap, Electronegativity (χ), Global Hardness (η), Global Softness (S) and Electrophilicity Index (ω). The calculated HOMO-LUMO gap exhibits interesting odd-even alteration behaviour, indicating that even numbered clusters possess higher stability as compare to their neighbour odd numbered clusters. This study also reflects a very well agreement between experimental bond length and computed data.

  3. Computational study of AuSi{sub n} (n=1-9) nanoalloy clusters invoking DFT based descriptors

    Energy Technology Data Exchange (ETDEWEB)

    Ranjan, Prabhat; Kumar, Ajay [Department of Mechatronics, Manipal University Jaipur Dehmi Kalan, Jaipur-303007 (India); Chakraborty, Tanmoy, E-mail: tanmoy.chakraborty@jaipur.manipal.edu, E-mail: tanmoychem@gmail.com [Department of Chemistry, Manipal University Jaipur Dehmi Kalan, Jaipur-303007 (India)

    2016-04-13

    Nanoalloy clusters formed between Au and Si are topics of great interest today from both scientific and technological point of view. Due to its remarkable catalytic, electronic, mechanical and magnetic properties Au-Si nanoalloy clusters have extensive applications in the field of microelectronics, catalysis, biomedicine, and jewelry industry. Density Functional Theory (DFT) is a new paradigm of quantum mechanics, which is very much popular to study the electronic properties of materials. Conceptual DFT based descriptors have been invoked to correlate the experimental properties of nanoalloy clusters. In this venture, we have systematically investigated AuSi{sub n} (n=1-9) nanoalloy clusters in the theoretical frame of the B3LYP exchange correlation. The experimental properties of AuSi{sub n} (n=1-9) nanoalloy clusters are correlated in terms of DFT based descriptors viz. HOMO-LUMO gap, Electronegativity (χ), Global Hardness (η), Global Softness (S) and Electrophilicity Index (ω). The calculated HOMO-LUMO gap exhibits interesting odd-even alteration behaviour, indicating that even numbered clusters possess higher stability as compare to their neighbour odd numbered clusters. This study also reflects a very well agreement between experimental bond length and computed data.

  4. Spectroscopic characterization, antimicrobial activity, DFT computation and docking studies of sulfonamide Schiff bases

    Science.gov (United States)

    Mondal, Sudipa; Mandal, Santi M.; Mondal, Tapan Kumar; Sinha, Chittaranjan

    2017-01-01

    Schiff bases synthesised from the condensation of 2-(hydroxy)naphthaldehyde and sulfonamides (sufathiazole (STZ), sulfapyridine (SPY), sulfadiazine (SDZ), sulfamerazine (SMZ) and sulfaguanidine (SGN)) are characterized by different spectroscopic data (FTIR, UV-Vis, Mass, NMR) and two of them, (E)-4-(((2-hydroxynaphthalen-1-yl)methylene)amino)-N-(thiazol-2-yl)benzenesulfonamide (1a) and (E)-N-(diaminomethylene)-4-(((2-hydroxynaphthalen-1-yl)methylene)amino)benzenesulfonamide (1e) have been confirmed by single crystal X-ray structure determination. Antimicrobial activities of the Schiff bases have been evaluated against certified and resistant Gram positive (Staphylococcus aureus, Enterococcus facelis) and Gram negative (Streptococcus pyogenes, Salmonella typhi, Shigella dysenteriae, Shigella flexneri, Klebsiella pneumonia) pathogens. Performance of Schiff base against the resistant pathogens are better than standard stain and MIC data lie 32-128 μg/ml while parent sulfonamides are effectively inactive (MIC >512 μg/ml). The DFT optimized structures of the Schiff bases have been used to accomplish molecular docking studies with DHPS (dihydropteroate synthase) protein structure (downloaded from Protein Data Bank) to establish the most preferred mode of interaction. ADMET filtration, Cytotoxicity (MTT assay) and haemolysis assay have been examined for evaluation of druglike character.

  5. Computing m DFT's over GF(q) with one DFT over GF(q^m)

    OpenAIRE

    Hong, Jonathan; Vetterli, Martin

    1993-01-01

    Over the field of complex numbers, it is well-known that if the input is real then it is possible to compute 2 real DFT's with one complex DFT. We extend the result to finite fields and show how to compute m DFT's over GF(q) with one DFT over GF(qm)

  6. Quantitative Vapor-phase IR Intensities and DFT Computations to Predict Absolute IR Spectra based on Molecular Structure: I. Alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Stephen D.; Johnson, Timothy J.; Sharpe, Steven W.; Yavelak, Veronica; Oats, R. P.; Brauer, Carolyn S.

    2013-11-13

    Recently recorded quantitative IR spectra of a variety of gas-phase alkanes are shown to have integrated intensities in both the C-H stretching and C-H bending regions that depend linearly on the molecular size, i.e. the number of C-H bonds. This result is well predicted from CH4 to C15H32 by DFT computations of IR spectra at the B3LYP/6-31+G(d,p) level of DFT theory. A simple model predicting the absolute IR band intensities of alkanes based only on structural formula is proposed: For the C-H stretching band near 2930 cm-1 this is given by (in km/mol): CH¬_str = (34±3)*CH – (41±60) where CH is number of C-H bonds in the alkane. The linearity is explained in terms of coordinated motion of methylene groups rather than the summed intensities of autonomous -CH2- units. The effect of alkyl chain length on the intensity of a C-H bending mode is explored and interpreted in terms of conformer distribution. The relative intensity contribution of a methyl mode compared to the total C-H stretch intensity is shown to be linear in the number of terminal methyl groups in the alkane, and can be used to predict quantitative spectra a priori based on structure alone.

  7. Spectroscopic, thermal analysis and DFT computational studies of salen-type Schiff base complexes

    Science.gov (United States)

    Ebrahimi, Hossein Pasha; Hadi, Jabbar S.; Abdulnabi, Zuhair A.; Bolandnazar, Zeinab

    2014-01-01

    A new series of metal(II) complexes of Co(II), Ni(II), Cu(II), Zn(II), and Pb(II) have been synthesized from a salen-type Schiff base ligand derived from o-vanillin and 4-methyl-1,2-phenylenediamine and characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR, 13C NMR and EI-mass), molar conductance measurements and thermal analysis techniques. Coats-Redfern method has been utilized to calculate the kinetic and thermodynamic parameters of the metal complexes. The molecular geometry, Mulliken atomic charges of the studied compounds were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values. The theoretical 13C chemical shift results of the studied compounds have been calculated at the B3LYP, PBEPBE and PW91PW91 methods and standard 6-311+G(d,p) basis set starting from optimized geometry. The comparison of the results indicates that B3LYP/6-311+G(d,p) yields good agreement with the observed chemical shifts. The measured low molar conductance values in DMF indicate that the metal complexes are non-electrolytes. The spectral and thermal analysis reveals that all complexes have octahedral geometry except Cu(II) complex which can attain the square planner arrangement. The presence of lattice and coordinated water molecules are indicated by thermograms of the complexes. The thermogravimetric (TG/DTG) analyses confirm high stability for all complexes followed by thermal decomposition in different steps.

  8. Quantitative vapor-phase IR intensities and DFT computations to predict absolute IR spectra based on molecular structure: I. Alkanes

    Science.gov (United States)

    Williams, Stephen D.; Johnson, Timothy J.; Sharpe, Steven W.; Yavelak, Veronica; Oates, R. P.; Brauer, Carolyn S.

    2013-11-01

    Recently recorded quantitative IR spectra of a variety of gas-phase alkanes are shown to have integrated intensities in both the C3H stretching and C3H bending regions that depend linearly on the molecular size, i.e. the number of C3H bonds. This result is well predicted from CH4 to C15H32 by density functional theory (DFT) computations of IR spectra using Becke's three parameter functional (B3LYP/6-31+G(d,p)). Using the experimental data, a simple model predicting the absolute IR band intensities of alkanes based only on structural formula is proposed: For the C3H stretching band envelope centered near 2930 cm-1 this is given by (km/mol) CH_str=(34±1)×CH-(41±23) where CH is number of C3H bonds in the alkane. The linearity is explained in terms of coordinated motion of methylene groups rather than the summed intensities of autonomous -CH2-units. The effect of alkyl chain length on the intensity of a C3H bending mode is explored and interpreted in terms of conformer distribution. The relative intensity contribution of a methyl mode compared to the total C3H stretch intensity is shown to be linear in the number of methyl groups in the alkane, and can be used to predict quantitative spectra a priori based on structure alone.

  9. Adaptive DFT-based Interferometer Fringe Tracking

    Science.gov (United States)

    Wilson, Edward; Pedretti, Ettore; Bregman, Jesse; Mah, Robert W.; Traub, Wesley A.

    2004-01-01

    An automatic interferometer fringe tracking system has been developed, implemented, and tested at the Infrared Optical Telescope Array (IOTA) observatory at Mt. Hopkins, Arizona. The system can minimize the optical path differences (OPDs) for all three baselines of the Michelson stellar interferometer at IOTA. Based on sliding window discrete Fourier transform (DFT) calculations that were optimized for computational efficiency and robustness to atmospheric disturbances, the algorithm has also been tested extensively on off-line data. Implemented in ANSI C on the 266 MHz PowerPC processor running the VxWorks real-time operating system, the algorithm runs in approximately 2.0 milliseconds per scan (including all three interferograms), using the science camera and piezo scanners to measure and correct the OPDs. The adaptive DFT-based tracking algorithm should be applicable to other systems where there is a need to detect or track a signal with an approximately constant-frequency carrier pulse.

  10. IR Spectra and Bond Energies Computed Using DFT

    Science.gov (United States)

    Bauschlicher, Charles; Andrews, Lester; Arnold, James (Technical Monitor)

    2000-01-01

    The combination of density functional theory (DFT) frequencies and infrared (IR) intensities and experimental spectra is a very powerful tool in the identification of molecules and ions. The computed and measured isotopic ratios make the identification much more secure than frequencies and intensities alone. This will be illustrated using several examples, such as Mn(CO)n and Mn(CO)n-. The accuracy of DFT metal-ligand bond energies will also be discussed.

  11. Computational Molecular Electronic Spectroscopy with TD-DFT.

    Science.gov (United States)

    Jacquemin, Denis; Adamo, Carlo

    2016-01-01

    In this chapter we present applications of TD-DFT aiming at reproducing and rationalizing the optical signatures of molecules, and, more precisely, the absorption and fluorescence spectra of conjugated compounds belonging to both organic and inorganic families. We particularly focus on the computations going beyond the vertical approximation, i.e., on the calculation of 0-0 energies and vibronic spectra with TD-DFT, and on large applications performed for "real-life" structures (organic and inorganic dyes, optimization of charge-transfer structures, rationalization of excited-state proton transfer, etc.). We present a series of recent applications of TD-DFT methodology for these different aspects. The main conclusions of TD-DFT benchmarks aiming at pinpointing the most suited exchange-correlation functionals are also discussed.

  12. Wavelet-Based DFT calculations on Massively Parallel Hybrid Architectures

    Science.gov (United States)

    Genovese, Luigi

    2011-03-01

    In this contribution, we present an implementation of a full DFT code that can run on massively parallel hybrid CPU-GPU clusters. Our implementation is based on modern GPU architectures which support double-precision floating-point numbers. This DFT code, named BigDFT, is delivered within the GNU-GPL license either in a stand-alone version or integrated in the ABINIT software package. Hybrid BigDFT routines were initially ported with NVidia's CUDA language, and recently more functionalities have been added with new routines writeen within Kronos' OpenCL standard. The formalism of this code is based on Daubechies wavelets, which is a systematic real-space based basis set. As we will see in the presentation, the properties of this basis set are well suited for an extension on a GPU-accelerated environment. In addition to focusing on the implementation of the operators of the BigDFT code, this presentation also relies of the usage of the GPU resources in a complex code with different kinds of operations. A discussion on the interest of present and expected performances of Hybrid architectures computation in the framework of electronic structure calculations is also adressed.

  13. On the number of multiplications necessary to compute a length-2 exp n DFT

    Science.gov (United States)

    Heideman, M. T.; Burrus, C. S.

    1986-01-01

    The number of multiplications necessary and sufficient to compute a length-2 exp n DFT is determined. The method of derivation is shown to apply to the multiplicative complexity results of Winograd (1980, 1981) for a length-p exp n DFT, for p an odd prime number. The multiplicative complexity of the one-dimensional DFT is summarized for many possible lengths.

  14. Lubrication Chemistry Viewed from DFT-Based Concepts and Electronic Structural Principles

    Directory of Open Access Journals (Sweden)

    Jin Yuansheng

    2003-12-01

    Full Text Available Abstract: Fundamental molecular issues in lubrication chemistry were reviewed under categories of solution chemistry, contact chemistry and tribochemistry. By introducing the Density Functional Theory(DFT-derived chemical reactivity parameters (chemical potential, electronegativity, hardness, softness and Fukui function and related electronic structural principles (electronegativity equalization principle, hard-soft acid-base principle, and maximum hardness principle, their relevancy to lubrication chemistry was explored. It was suggested that DFT, theoretical, conceptual and computational, represents a useful enabling tool to understand lubrication chemistry issues prior to experimentation and the approach may form a key step in the rational design of lubrication chemistry via computational methods. It can also be optimistically anticipated that these considerations will gestate unique DFT-based strategies to understand sophisticated tribology themes, such as origin of friction, essence of wear, adhesion in MEMS/NEMS, chemical mechanical polishing in wafer manufacturing, stress corrosion, chemical control of friction and wear, and construction of designer tribochemical systems.

  15. Hardware efficient implementation of DFT using an improved first-order moments based cyclic convolution structure

    Science.gov (United States)

    Xiong, Jun; Liu, J. G.; Cao, Li

    2015-12-01

    This paper presents hardware efficient designs for implementing the one-dimensional (1D) discrete Fourier transform (DFT). Once DFT is formulated as the cyclic convolution form, the improved first-order moments-based cyclic convolution structure can be used as the basic computing unit for the DFT computation, which only contains a control module, a barrel shifter and (N-1)/2 accumulation units. After decomposing and reordering the twiddle factors, all that remains to do is shifting the input data sequence and accumulating them under the control of the statistical results on the twiddle factors. The whole calculation process only contains shift operations and additions with no need for multipliers and large memory. Compared with the previous first-order moments-based structure for DFT, the proposed designs have the advantages of less hardware consumption, lower power consumption and the flexibility to achieve better performance in certain cases. A series of experiments have proven the high performance of the proposed designs in terms of the area time product and power consumption. Similar efficient designs can be obtained for other computations, such as DCT/IDCT, DST/IDST, digital filter and correlation by transforming them into the forms of the first-order moments based cyclic convolution.

  16. Electronic Absorption Spectra of Tetrapyrrole-Based Pigments via TD-DFT: A Reduced Orbital Space Study.

    Science.gov (United States)

    Shrestha, Kushal; Virgil, Kyle A; Jakubikova, Elena

    2016-07-28

    Tetrapyrrole-based pigments play a crucial role in photosynthesis as principal light absorbers in light-harvesting chemical systems. As such, accurate theoretical descriptions of the electronic absorption spectra of these pigments will aid in the proper description and understanding of the overall photophysics of photosynthesis. In this work, time-dependent density functional theory (TD-DFT) at the CAM-B3LYP/6-31G* level of theory is employed to produce the theoretical absorption spectra of several tetrapyrrole-based pigments. However, the application of TD-DFT to large systems with several hundreds of atoms can become computationally prohibitive. Therefore, in this study, TD-DFT calculations with reduced orbital spaces (ROSs) that exclude portions of occupied and virtual orbitals are pursued as a viable, computationally cost-effective alternative to conventional TD-DFT calculations. The effects of reducing orbital space size on theoretical spectra are qualitatively and quantitatively described, and both conventional and ROS results are benchmarked against experimental absorption spectra of various tetrapyrrole-based pigments. The orbital reduction approach is also applied to a large natural pigment assembly that comprises the principal light-absorbing component of the reaction center in purple bacteria. Overall, we find that TD-DFT calculations with proper and judicious orbital space reductions can adequately reproduce conventional, full orbital space, TD-DFT results of all pigments studied in this work.

  17. What have we learned from modeling carbohydrates using cutting edge (DFT) computational tools?

    Science.gov (United States)

    Over the last decade there have been vast improvements in computer speed and also in the development of reliable density functional methods (DFT). These improvements have allowed a rigorous and systematic study of carbohydrates to be carried out. Recent publications from this laboratory, in the ar...

  18. Conformational analysis of menthol diastereomers by NMR and DFT computation

    Science.gov (United States)

    Härtner, Julia; Reinscheid, Uwe M.

    2008-01-01

    Correlations between experimental and calculated 13C chemical shifts were performed with the series of all menthol diastereomers. In this way it could be shown that identification problems with newly isolated natural products can be solved. Starting from simulated, low energy conformers of menthol, neomenthol, isomenthol, and neoisomenthol the 13C chemical shifts were obtained using DFT calculations [functional: B3LYP, basis set: 6-31G(d,p)]. Due to differences in chemical shifts, the prochiral methyl groups of the isopropyl substituent of menthol could be differentiated using the correlations between experimental and calculated values. A conformational scan of the dihedral angle of the isopropyl group allowed the determination of the dominating rotamers of menthol (+68.4°) and neomenthol (+172.5°) using 13C chemical shifts. The results were supported by energy calculations, 1JCH and 3JHH measurements. The correlations and 3JHH measurements for isomenthol indicate conformational averaging impeding the determination of the isopropyl group rotamer. For neoisomenthol, MD simulations showed two chair conformations. However, in contrast to calculated energies and correlations between theoretical and experimental 13C chemical shifts, the measured 3JH3H2 coupling of 6.3 Hz indicates an equally populated equilibrium of both conformers.

  19. DFT-based offset-QAM OFDM for optical communications.

    Science.gov (United States)

    Zhao, Jian

    2014-01-13

    We experimentally demonstrate and numerically investigate a discrete-Fourier-transform (DFT) based offset quadrature-amplitude-modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) system. We investigate the scheme using a set of square-root-raised-cosine functions and a set of super-Gaussian functions as signal spectra. It is shown that offset-QAM OFDM exhibits negligible penalty for all investigated spectra, in contrast to rectangular-function based Nyquist FDM (N-FDM) and sinc-function based conventional OFDM (C-OFDM). The required guard interval (GI) length for dispersion compensation in offset-QAM OFDM is analyzed and shown to scale with twice the subcarrier spacing rather than the full OFDM bandwidth. Experimental results show that 38-Gb/s offset-16QAM OFDM supports 600-km fiber transmission with negligible penalty in the absence of GI while a GI length of eight is required in C-OFDM. Further numerical simulations show that by avoiding the GI, 112-Gb/s polarization multiplexed offset-4QAM OFDM can achieve 23% increase in net data rate over C-OFDM under the same transmission reach. We also discuss the design of the pulse-shaping filter in the DFT-based implementation and show that when compared to N-FDM, the required memory length of the filter for pulse shaping can be reduced from 60 to 2 in offset-QAM OFDM regardless of the fiber length.

  20. Ab-initio and DFT methodologies for computing hyperpolarizabilities and susceptibilities of highly conjugated organic compounds for nonlinear optical applications

    Science.gov (United States)

    Karakas, A.; Karakaya, M.; Ceylan, Y.; El Kouari, Y.; Taboukhat, S.; Boughaleb, Y.; Sofiani, Z.

    2016-06-01

    In this talk, after a short introduction on the methodologies used for computing dipole polarizability (α), second and third-order hyperpolarizability and susceptibility; the results of theoretical studies performed on density functional theory (DFT) and ab-initio quantum mechanical calculations of nonlinear optical (NLO) properties for a few selected organic compounds and polymers will be explained. The electric dipole moments (μ) and dispersion-free first hyperpolarizabilities (β) for a family of azo-azulenes and a styrylquinolinium dye have been determined by DFT at B3LYP level. To reveal the frequency-dependent NLO behavior, the dynamic α, second hyperpolarizabilities (γ), second (χ(2)) and third-order (χ(3)) susceptibilites have been evaluated using time-dependent HartreeFock (TDHF) procedure. To provide an insight into the third-order NLO phenomena of a series of pyrrolo-tetrathiafulvalene-based molecules and pushpull azobenzene polymers, two-photon absorption (TPA) characterizations have been also investigated by means of TDHF. All computed results of the examined compounds are compared with their previous experimental findings and the measured data for similar structures in the literature. The one-photon absorption (OPA) characterizations of the title molecules have been theoretically obtained by configuration interaction (CI) method. The highest occupied molecular orbitals (HOMO), the lowest unoccupied molecular orbitals (LUMO) and the HOMO-LUMO band gaps have been revealed by DFT at B3LYP level for azo-azulenes, styrylquinolinium dye, push-pull azobenzene polymers and by parametrization method 6 (PM6) for pyrrolo-tetrathiafulvalene-based molecules.

  1. LOBSTER: A tool to extract chemical bonding from plane-wave based DFT.

    Science.gov (United States)

    Maintz, Stefan; Deringer, Volker L; Tchougréeff, Andrei L; Dronskowski, Richard

    2016-04-30

    The computer program LOBSTER (Local Orbital Basis Suite Towards Electronic-Structure Reconstruction) enables chemical-bonding analysis based on periodic plane-wave (PAW) density-functional theory (DFT) output and is applicable to a wide range of first-principles simulations in solid-state and materials chemistry. LOBSTER incorporates analytic projection routines described previously in this very journal [J. Comput. Chem. 2013, 34, 2557] and offers improved functionality. It calculates, among others, atom-projected densities of states (pDOS), projected crystal orbital Hamilton population (pCOHP) curves, and the recently introduced bond-weighted distribution function (BWDF). The software is offered free-of-charge for non-commercial research. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.

  2. Self-interaction error in DFT-based modelling of ionic liquids.

    Science.gov (United States)

    Lage-Estebanez, Isabel; Ruzanov, Anton; García de la Vega, José M; Fedorov, Maxim V; Ivaništšev, Vladislav B

    2016-01-21

    The modern computer simulations of potential green solvents of the future, involving the room temperature ionic liquids, heavily rely on density functional theory (DFT). In order to verify the appropriateness of the common DFT methods, we have investigated the effect of the self-interaction error (SIE) on the results of DFT calculations for 24 ionic pairs and 48 ionic associates. The magnitude of the SIE is up to 40 kJ mol(-1) depending on the anion choice. Most strongly the SIE influences the calculation results of ionic associates that contain halide anions. For these associates, the range-separated density functionals suppress the SIE; for other cases, the revPBE density functional with dispersion correction and triple-ζ Slater-type basis is suitable for computationally inexpensive and reasonably accurate DFT calculations.

  3. Topology of the interactions pattern in pharmaceutically relevant polymorphs of methylxanthines (caffeine, theobromine, and theophiline): combined experimental (¹H-¹⁴N nuclear quadrupole double resonance) and computational (DFT and Hirshfeld-based) study.

    Science.gov (United States)

    Latosińska, Jolanta Natalia; Latosińska, Magdalena; Olejniczak, Grzegorz A; Seliger, Janez; Žagar, Veselko

    2014-09-22

    Three anhydrous methylxanthines: caffeine (1,3,7-trimethylxanthine; 1,3,7-trimethyl-1H-purine-2,6-(3H,7H)-dione) and its two metabolites theophylline (1,3-dimethylxanthine; 1,3-dimethyl-7H-purine-2,6-dione) and theobromine (3,7-dimethyl-xanthine; 3,7-dimethyl-7H-purine-2,6-dione), which reveal multifaceted therapeutic potential, have been studied experimentally in solid state by (1)H-(14)N NMR-NQR (nuclear magnetic resonance-nuclear quadrupole resonance) double resonance (NQDR). For each compound the complete NQR spectrum consisting of 12 lines was recorded. The multiplicity of NQR lines indicates the presence of a stable β form of anhydrous caffeine at 233 K and stable form II of anhydrous theobromine at 213 K. The assignment of signals detected in NQR experiment to particular nitrogen atoms was made on the basis of quantum chemistry calculations performed for monomer, cluster, and solid at the DFT/GGA/BLYP/DPD level. The shifts due to crystal packing interactions were evaluated, and the multiplets detected by NQR were assigned to N(9) in theobromine and N(1) and N(9) in caffeine. The ordering theobromine > theophylline > caffeine site and theophylline theobromine theobromine) to π···π stacking (caffeine). Substantial differences in the intermolecular interactions in stable forms of methylxanthines differing in methylation (site or number) were analyzed within the Hirshfeld surface-based approach. The analysis of local environment of the nitrogen nucleus permitted drawing some conclusions on the nature of the interactions required for effective processes of recognition and binding of a given methylxanthine to A1-A(2A) receptor (target for caffeine in the brain). Although the interactions responsible for linking neighboring methylxanthines molecules in crystals and methylxanthines with targets in the human organism can differ significantly, the knowledge of the topology of interactions provides reliable preliminary information about the nature of this binding.

  4. Formation of a 6FDA-based ring polyimide with nanoscale cavity evaluated by DFT calculations

    Science.gov (United States)

    Fukuda, Mitsuhiro; Takao, Yoshimi; Tamai, Yoshinori

    2005-04-01

    The computer-aided molecular design of a rigid ring molecule has been performed. As a candidate molecule, the polyimide derived from 2,2-bis(3,4-carboxylphenyl) hexafluoropropane dianhydride (6FDA) with m-phenylenediamine (MDA) has been used. The optimized structures of the 6FDA-MDA model compounds including a precursor type amic acid model were investigated using the density functional theory (DFT) at the B3LYP/6-311G(d,p) level. Using the optimized structures of the model compounds, the probable combinations to form a flat ring polyimide are considered by taking the spatial angles between the respective aromatic groups into consideration. We selected several combinations with different conformations and the number of monomer units. We showed that the dimer, trimer and tetramer of not only the 6FDA-based ring imide but also the corresponding ring amic acid can have a stable geometry. Each of them contains a cavity of sub-nanometer size and characteristic shape. Among them, the interaction energy with some guest molecules are evaluated for the smallest ring imide constructed from two units of 6FDA-MDA using the DFT calculations.

  5. Spectroscopic and DFT-based computational studies on the molecular electronic structural characteristics and the third-order nonlinear property of an organic NLO crystal: (E)-N‧-(4-chlorobenzylidene)-4-methylbenzenesulfonohydrazide

    Science.gov (United States)

    Sasikala, V.; Sajan, D.; Joseph, Lynnette; Balaji, J.; Prabu, S.; Srinivasan, P.

    2017-04-01

    Single crystals of (E)-N‧-(4-chlorobenzylidene)-4-methylbenzenesulfonohydrazide (CBMBSH) have been grown by slow evaporation crystal growth method. The structure stabilizing intramolecular donor-acceptor interactions and the presence of the Nsbnd H⋯O, Csbnd H⋯O and Csbnd H⋯C(π) hydrogen bonds in the crystal were confirmed by vibrational spectroscopic and DFT methods. The linear optical absorption characteristics of the solvent phase of CBMBSH were investigated using UV-Vis-NIR spectroscopic and TD-DFT approaches. The 2PA assisted RSA nonlinear absorption and the optical limiting properties of CBMBSH were studied using the open-aperture Z-scan method. The topological characteristics of the electron density have been determined using the quantum theory of atoms in molecules method.

  6. Secure Image Transmission over DFT-precoded OFDM-VLC systems based on Chebyshev Chaos scrambling

    Science.gov (United States)

    Wang, Zhongpeng; Qiu, Weiwei

    2017-08-01

    This paper proposes a physical layer image secure transmission scheme for discrete Fourier transform (DFT) precoded OFDM-based visible light communication systems by using Chebyshev chaos maps. In the proposed scheme, 256 subcarriers and QPSK modulation are employed. The transmitted digital signal of the image is encrypted with a Chebyshev chaos sequence. The encrypted signal is then transformed by a DFT precoding matrix to reduce the PAPR of the OFDM signal. After that, the encrypted and DFT-precoded OFDM are transmitted over a VLC channel. The simulation results show that the proposed image security transmission scheme can not only protect the DFT-precoded OFDM-based VLC from eavesdroppers but also improve BER performance.

  7. The electronic character of PTCDA thin films in comparison to other perylene-based organic semi-conductors: ab initio-, TD-DFT and semi-empirical computations of the opto-electronic properties of large aggregates.

    Science.gov (United States)

    Bellinger, Daniel; Pflaum, Jens; Brüning, Christoph; Engel, Volker; Engels, Bernd

    2017-01-18

    Perylene-based compounds are promising materials for opto-electronic thin film devices but despite intense investigations, important details of their electronic structure are still under debate. For perylene-3,4,9,10-tetracarboxylic dianhydrid (PTCDA), the theoretical models predict a different relative energetic order of Frenkel and Charge Transfer (CT) states. Additionally, while one model indicates strong differences between PTCDA on one hand and other perylene-based compounds on the other, recent ab initio computations indicate electronic properties of all perylene-based compounds to resemble each other. Finally, the models disagree about the amount of mixing between CT and Frenkel states. Definitive answers to these questions are difficult because the approaches use various approximations. Up to date, the ab initio based methods employ rather small model systems and neglect environmental effects. In the present work, we improve our former approach by analyzing the effects of the various simplifications. In more detail, we increase the size of the model systems, include environmental effects and investigate the influence of exciton-phonon couplings on the absorption spectrum. The computations for larger aggregates were performed with the ZINDO/S approach, because benchmark computations show that it provides accurate vertical excitation energies for Frenkel, as well as CT states.

  8. Conformations of propargyl alcohol and its interaction with acetylene: A matrix isolation infrared and DFT computations

    Science.gov (United States)

    Sundararajan, K.; Gopi, R.; Ramanathan, N.

    2016-10-01

    Conformations of propargyl alcohol (PA) were studied using matrix isolation infrared spectroscopy. DFT computations using 6-311++G(d,p) basis set on the PA molecule identified two minima; gauche (g-PA) and trans (t-PA). Comparison of infrared spectra of PA trapped in Ar, N2 and Xe matrices with computations showed the evidence of the ground state g-PA conformer. Four minima were optimized on the potential energy surface for the hydrogen-bonded interaction of g-PA and acetylene (C2H2), corresponding to complex A (Csbnd H⋯O), complex B (Osbnd H⋯π) and complex C and D (Csbnd H⋯π). The structure, energies and the vibrational wavenumbers were computed for these complexes at B3LYP/6-311++G (d,p) level of theory. The infrared spectra of the hydrogen-bonded complexes between C2H2 and g-PA were studied in Ar matrix. The infrared spectra recorded under matrix isolation conditions revealed the formation of two types of complexes A (Csbnd H⋯O) and B (Osbnd H⋯π). Formation of these complexes was evidenced from the shifts in the vibrational wavenumber of the modes involving the C2H2 and PA submolecules.

  9. Study of structure and spectroscopy of water-hydroxide ion clusters: A combined simulated annealing and DFT-based approach

    Indian Academy of Sciences (India)

    Satyajit Guha; Soumya Ganguly Neogi; Pinaki Chaudhury

    2014-05-01

    In this paper, we explore the use of stochastic optimizer, namely simulated annealing (SA) followed by density function theory (DFT)-based strategy for evaluating the structure and infrared spectroscopy of (H2O) OH− clusters where = 1-6. We have shown that the use of SA can generate both global and local structures of these cluster systems.We also perform a DFT calculation, using the optimized coordinate obtained from SA as input and extract the IR spectra of these systems. Finally, we compare our results with available theoretical and experimental data. There is a close correspondence between the computed frequencies from our theoretical study and available experimental data. To further aid in understanding the details of the hydrogen bonds formed, we performed atoms in molecules calculation on all the global minimum structures to evaluate relevant electron densities and critical points.

  10. A theoretical analysis of bi-metallic (Cu–Agn = 1 − 7 nano alloy clusters invoking DFT based descriptors

    Directory of Open Access Journals (Sweden)

    Ranjan Prabhat

    2015-12-01

    Full Text Available Due to its large scale applications in the real field, the study of bi-metallic nano-alloy clusters is an active field of research. Though a number of experimental reports are available in this domain, a deep theoretical insight is yet to receive. Among several nano-clusters, the compound formed between Cu–Ag has gained a large importance due to its remarkable optical property. Density Functional Theory (DFT is one of the most popular approaches of quantum mechanics to study the electronic properties of materials. Conceptually, DFT based descriptors have turned to be indispensable tools for analyzing and correlating the experimental properties of compounds. In this venture, we have analyzed the experimental properties of the (Cu–Agn = 1 − 7 nano-alloy clusters invoking DFT methodology. A nice correlation has been found between optical properties of the aforesaid nano-clusters with our evaluated theoretical descriptors. The similar agreement between experimental bond length and computed data is also reflected in this analysis. Beside these, the effect of even-odd alternation behavior of nano compounds on the HOMO-LUMO gap is very important in our computation. It is probably the first attempt to establish such type of correlation.

  11. Spectroscopic investigation, HOMO-LUMO and NLO studies on L-histidinium maleate based on DFT approach

    Science.gov (United States)

    Dhanavel, S.; Stephen, A.; Asirvatham, P. Samuel

    2017-05-01

    The molecular structure of the title compound L-Histidinium Maleate (LHM) was constructed and optimized based on Density Functional Theory method (DFT-B3LYP) with the 6-31G (d,p) basis set. The fundamental vibrational spectral assignment was analyzed with the aid of optimized structure of LHM. The study on electronic properties such as, HOMO-LUMO energies and absorption wavelength were performed using Time dependent DFT (TD-DFT) approach which reveals that energy transfer occur within the molecule. 13C NMR chemical shift values were measured using Gauge independent atomic orbital method (GIAO) and the obtained values are in good agreement with the reported experimental values. Hardness, ionization potential and electrophilicity index also calculated. The electric dipole moment (μtot) and hyperpolarizability (βtot) values of the investigated molecules were computed. The calculated value (β) was 3.7 times higher than that of urea, which confirms the LHM molecule is a potential candidate for NLO applications.

  12. Towards the versatile DFT and MP2 computational schemes for 31P NMR chemical shifts taking into account relativistic corrections.

    Science.gov (United States)

    Fedorov, Sergey V; Rusakov, Yury Yu; Krivdin, Leonid B

    2014-11-01

    The main factors affecting the accuracy and computational cost of the calculation of (31)P NMR chemical shifts in the representative series of organophosphorous compounds are examined at the density functional theory (DFT) and second-order Møller-Plesset perturbation theory (MP2) levels. At the DFT level, the best functionals for the calculation of (31)P NMR chemical shifts are those of Keal and Tozer, KT2 and KT3. Both at the DFT and MP2 levels, the most reliable basis sets are those of Jensen, pcS-2 or larger, and those of Pople, 6-311G(d,p) or larger. The reliable basis sets of Dunning's family are those of at least penta-zeta quality that precludes their practical consideration. An encouraging finding is that basically, the locally dense basis set approach resulting in a dramatic decrease in computational cost is justified in the calculation of (31)P NMR chemical shifts within the 1-2-ppm error. Relativistic corrections to (31)P NMR absolute shielding constants are of major importance reaching about 20-30 ppm (ca 7%) improving (not worsening!) the agreement of calculation with experiment. Further better agreement with the experiment by 1-2 ppm can be obtained by taking into account solvent effects within the integral equation formalism polarizable continuum model solvation scheme. We recommend the GIAO-DFT-KT2/pcS-3//pcS-2 scheme with relativistic corrections and solvent effects taken into account as the most versatile computational scheme for the calculation of (31)P NMR chemical shifts characterized by a mean absolute error of ca 9 ppm in the range of 550 ppm.

  13. Lubrication Chemistry Viewed from DFT-Based Concepts and Electronic Structural Principles

    OpenAIRE

    Jin Yuansheng; Yang He; Li Shenghua

    2003-01-01

    Abstract: Fundamental molecular issues in lubrication chemistry were reviewed under categories of solution chemistry, contact chemistry and tribochemistry. By introducing the Density Functional Theory(DFT)-derived chemical reactivity parameters (chemical potential, electronegativity, hardness, softness and Fukui function) and related electronic structural principles (electronegativity equalization principle, hard-soft acid-base principle, and maximum hardness principle), their relevancy to lu...

  14. Molecular structure, vibrational spectra and DFT computational studies of melaminium N-acetylglycinate dihydrate

    Science.gov (United States)

    Tanak, H.; Pawlus, K.; Marchewka, M. K.

    2016-10-01

    Melaminium N-acetylglycinate dihydrate, an organic material has been synthesized and characterized by X-ray diffraction, FT-IR, and FT-Raman spectroscopies for the protiated and deuteriated crystals. The title complex crystallizes in the triclinic system, and the space group is P-1 with a = 5.642(1) Å, b = 7.773(2) Å, c = 15.775(3) Å, α = 77.28(1)°, β = 84.00(1)°, γ = 73.43(1)° and Z = 2. The molecular geometry, vibrational frequencies and intensity of the vibrational bands have been interpreted with the aid of structure optimization based on density functional method (B3LYP) with the 6-311++G(d,p) basis set. The obtained vibrational wavenumbers and optimized geometric parameters were seen to be in good agreement with the experimental data. The intermolecular hydrogen bonding interactions of the title compound have been investigated using the natural bonding orbital analysis. It reveals that the O-H···O, N-H···N and N-H···O intermolecular interactions significantly influence crystal packing of this molecule. The non-linear optical properties are also addressed theoretically. The predicted NLO properties of the title compound are much greater than ones of urea. In addition, DFT calculations of the title compound, molecular electrostatic potential, thermodynamic properties, frontier orbitals and chemical reactivity descriptors were also performed at 6-311++G(d,p) level of theory.

  15. [IR and Raman spectra studies of Rotundine based on DFT].

    Science.gov (United States)

    Li, Jun-Ping; Zhou, Guang-Ming; Zhang, Li-Jun; Cheng, Hong-Mei; Qin, Hong-Ying

    2014-11-01

    Infrared spectroscopy (IR), the normal Raman spectroscopy (NRS) and the surface enhanced Raman spectroscopy (SERS) in new Ag/Cu nanomaterial of Rotundine were studied in the present paper. The IR and the NRS of Rotundine were calculated by the density functional theory (DFT) using B3LYP/6-311+G(d, p), then the spectral intensity graph of Rotundine were given. The vibrational peaks were assigned comprehensively by the visualization software of Gauss view 5. 0. Rotundine has obvious infrared and Raman vibrational peak in the wave number range of 3 300-2500 and 1 800-600 cm(-1). SnCl2 and PVP was used as capping agent for the silver nanoparticles in SERS of Rotundine. Finally, by using the method of cyclic immersion well dispersed silver nanoparticles was obtained and achieved good enhancement effect. This molecule acquired strong selective enhancement vibration peak, In the wave number ranges of 1 500-1 400 and 1 000-700 cm(-1) the enhancement effect is most obvious. After analyzed, the methylene of this molecule is adsorbed on the silver nanoparticles surface and the angle between the benzene ring and the silver substrate is close to 90 degrees. The theoretically calculated spectra of Rotundine are consistent with the obtained experimental spectra. There are some differences may be due to the interaction forces between molecules and so on. The visualization software displayed the structure characteristics and molecular group vibration of this molecular visually and provided important basis for assigning the vibrational peaks. Rotundine is an important traditional Chinese medicine agent contained in many kinds of sedative drugs. The study provides a strong basis for the rapid, feature and trace identification of Rotundine and also supplies important reference for the biological role of central inhibition of analgesic drugs.

  16. Robust Object-Based Watermarking Using SURF Feature Matching and DFT Domain

    Directory of Open Access Journals (Sweden)

    M. Cedillo-Hernandez

    2013-12-01

    Full Text Available In this paper we propose a robust object-based watermarking method, in which the watermark is embedded into the middle frequencies band of the Discrete Fourier Transform (DFT magnitude of the selected object region, altogether with the Speeded Up Robust Feature (SURF algorithm to allow the correct watermark detection, even if the watermarked image has been distorted. To recognize the selected object region after geometric distortions, during the embedding process the SURF features are estimated and stored in advance to be used during the detection process. In the detection stage, the SURF features of the distorted image are estimated and match them with the stored ones. From the matching result, SURF features are used to compute the Affine-transformation parameters and the object region is recovered. The quality of the watermarked image is measured using the Peak Signal to Noise Ratio (PSNR, Structural Similarity Index (SSIM and the Visual Information Fidelity (VIF. The experimental results show the proposed method provides robustness against several geometric distortions, signal processing operations and combined distortions. The receiver operating characteristics (ROC curves also show the desirable detection performance of the proposed method. The comparison with a previously reported methods based on different techniques is also provided.

  17. Bis(terpyridine)-based surface template structures on graphite: a force field and DFT study.

    Science.gov (United States)

    Künzel, Daniela; Markert, Thomas; Gross, Axel; Benoit, David M

    2009-10-21

    Host-guest networks formed by ordered organic layers are promising candidates for applications in molecular storage and quantum computing. We have studied 2-dimensionally ordered surface template structures of bis(terpyridine)-derived molecules (BTPs) on graphite using force field and DFT methods and compared the results to recent experimental observations. In order to determine the force field best suited for surface calculations, bond lengths and angles, torsional potentials, adsorption and stacking energies of smaller aromatic molecules were calculated with different force fields (Compass, UFF, Dreiding and CVFF). Density functional perturbation theory calculations were used to study the intermolecular interactions between 3,3'-BTP molecules. Structural properties, adsorption energies and rotational barriers of the 3,3'-BTP surface structure and its host-guest systems with phthalocyanine (PcH(2)) or excess 3,3'-BTP as guest molecules have been addressed. In addition, STM images of oligopyridine and phthalocyanine molecules were simulated based on periodic and local density functional theory calculations.

  18. Implementation of Constrained DFT for Computing Charge Transfer Rates within the Projector Augmented Wave Method

    DEFF Research Database (Denmark)

    Melander, Marko; Jónsson, Elvar Örn; Mortensen, Jens Jørgen

    2016-01-01

    molecules to periodic systems in one-, two-, or three-dimensions. As such, this implementation is relevant for a wide variety of applications. We also present how to extract the electronic coupling element and reorganization energy from the resulting diabatic cDFT-PAW wave functions for the parametrization...

  19. Palladium(II) complex with thiazole containing tridentate ONN donor ligand: Synthesis, X-ray structure and DFT computation

    Science.gov (United States)

    Biswas, Sujan; Pramanik, Ajoy Kumar; Mondal, Tapan Kumar

    2015-05-01

    New palladium(II) complex with 2-(2-thiazolyl)-4-methylphenol (TAC) having general formula [Pd(TAC)Cl) (1) has been synthesized and characterized. The complex has been characterized by various spectroscopic techniques. Single crystal X-ray structure shows distorted square planar geometry around palladium(II). Cyclic voltammetric studies shows ligand based irreversible oxidation and reduction peaks. The electronic structure, redox properties and electronic excitations in the complex are interpreted by DFT and TDDFT calculations.

  20. Proton Affinities of Anionic Bases:  Trends Across the Periodic Table, Structural Effects, and DFT Validation.

    Science.gov (United States)

    Swart, Marcel; Bickelhaupt, F Matthias

    2006-03-01

    We have carried out an extensive exploration of the gas-phase basicity of archetypal anionic bases across the periodic system using the generalized gradient approximation of density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. First, we validate DFT as a reliable tool for computing proton affinities and related thermochemical quantities:  BP86/QZ4P//BP86/TZ2P is shown to yield a mean absolute deviation of 1.6 kcal/mol for the proton affinity at 0 K with respect to high-level ab initio benchmark data. The main purpose of this work is to provide the proton affinities (and corresponding entropies) at 298 K of the anionic conjugate bases of all main-group-element hydrides of groups 14-17 and periods 2-6. We have also studied the effect of stepwise methylation of the protophilic center of the second- and third-period bases.

  1. Probing C-H⋯N interaction in acetylene-benzonitrile complex using matrix isolation infrared spectroscopy and DFT computations

    Science.gov (United States)

    Gopi, R.; Ramanathan, N.; Sundararajan, K.

    2017-04-01

    Hydrogen-bonded complexes of acetylene (C2H2) and the benzonitrile (C6H5CN) have been investigated using matrix isolation infrared spectroscopy and DFT computations. The structure of the complexes and the energies were computed at B3LYP and B3LYP+D3 levels of theory using 6-311++G (d, p) and aug-cc-pVDZ basis sets. DFT computations indicated two minima corresponding to the C-H⋯N (global) and C-H⋯π interactions (local) of 1:1 C2H2-C6H5CN complexes, where C2H2 is the proton donor in both complexes. Experimentally, the 1:1 C-H⋯N complex identified from the shifts in the C-H and Ctbnd N stretching modes corresponding to the C2H2 and C6H5CN sub-molecules in N2 and Ar matrices. Atoms in Molecules and Natural Bond Orbital analyses were performed to understand the nature of interaction and to unravel the reasons for red-shifting of the C-H stretching frequency in these complexes. Energy decomposition analysis was carried out to discern the various stabilizing and destabilizing components as a result of hydrogen bonding in the C2H2-C6H5CN complexes.

  2. Experimental and DFT computational studies of L-alanine cadmium chloride crystals

    Science.gov (United States)

    Ignatius, I. Cicili; Dheivamalar, S.; Kirubavathi, K.; Selvaraju, K.

    2016-05-01

    In this work, we report the combined experimental and theoretical study on molecular structure and vibrational spectra of nonlinear optical crystal L-alanine cadmium chloride (LACC). The single X-ray diffraction studies have revealed that the compound crystallizes in monoclinic system C2 space group with cell parameters a = 16.270, b = 7.358, c = 7.887 and Z = 4. FTIR and Raman spectra of the nonlinear optical materials LACC have been recorded and analyzed. The optimized geometric bond length and bond angles are obtained with the help of density functional theory (DFT) (B3LYP) calculation. The optimized geometric bond lengths and bond angles obtained by using DFT show good agreement with the experimental data. Using the natural bond orbital analysis the electronic effect and hydrogen bonding were confirmed. The HOMO-LUMO energy gap and the first order hyperpolarizability were calculated and it supports the nonlinear optical activity of LACC crystal.

  3. Searching for DFT-based methods that include dispersion interactions to calculate the physisorption of H2 on benzene and graphene

    Science.gov (United States)

    Cabria, I.; López, M. J.; Alonso, J. A.

    2017-06-01

    Simulations of the hydrogen storage capacities of nanoporous carbons require an accurate treatment of the interaction of the hydrogen molecule with the graphite-like surfaces of the carbon pores, which is dominated by the dispersion forces. These interactions are described accurately by high level quantum chemistry methods, like the Coupled Cluster method with single and double excitations and a non-iterative correction for triple excitations (CCSD(T)), but those methods are computationally very expensive for large systems and for massive simulations. Density functional theory (DFT)-based methods that include dispersion interactions at different levels of complexity are less accurate, but computationally less expensive. In order to find DFT-methods that include dispersion interactions to calculate the physisorption of H2 on benzene and graphene, with a reasonable compromise between accuracy and computational cost, CCSD(T), Møller-Plesset second-order perturbation theory method, and several DFT-methods have been used to calculate the interaction energy curves of H2 on benzene and graphene. DFT calculations are compared with CCSD(T) calculations, in the case of H2 on benzene, and with experimental data, in the case of H2 on graphene. Among the DFT methods studied, the B97D, RVV10, and PBE+DCACP methods yield interaction energy curves of H2-benzene in remarkable agreement with the interaction energy curve obtained with the CCSD(T) method. With regards to graphene, the rev-vdW-DF2, PBE-XDM, PBE-D2, and RVV10 methods yield adsorption energies of the lowest level of H2 on graphene, very close to the experimental data.

  4. B3LYP, BLYP and PBE DFT band structures of the nucleotide base stacks

    Science.gov (United States)

    Szekeres, Zs; Bogár, F.; Ladik, J.

    DFT crystal orbital (band structure) calculations have been performed for the nucleotide base stacks of cytosine, thymine, adenine, and guanine arranged in DNA B geometry. The band structures obtained with PBE, BLYP, and B3LYP functionals are presented and compared to other related experimental and theoretical results. The influence of the quality of the basis set on the fundamental gap values was also investigated using Clementi's double ζ, 6-31G and 6-31G* basis sets.

  5. Origin of Metallization of FeO at High Temperatures and Pressures from First-principles DFT-DMFT Computations

    Science.gov (United States)

    Cohen, R. E.; Haule, K.

    2012-12-01

    Experiments and theory show that FeO metallizes at high temperatures (~2000K) and pressures (~80 GPa) [1]. The theory used is based on many-body theory for a quantum impurity self-consistently embedded in a crystal described by band theory, or DFT+Dynamical Mean Field Theory (DMFT). Here we discuss the origin of the metallization. We use an LAPW basis set, and the lattice terms are evaluated using the WIEN2K LAPW code. The impurity model is solved using continuous time quantum Monte Carlo (CTQMC). Temperature enters explicitly, so we made special efforts to understand high temperature behavior. The computations are fully self-consistent, including the impurity levels and crystal field splitting, and the total energy is evaluated using the full potential and charge density of the lattice plus impurity models. We find with increasing pressure in paramagnetic FeO in a cubic lattice a high-spin low-spin transition, with a wide transition region between characterized by intermediate occupancies of the t2g and eg states between. We find that at 300K cubic FeO remains insulating to a factor of two compression (over 600 GPa), except for a small region of high spin metal. However, at high temperatures (e.g. 2000K) a metallic state is found under compression. The metallization occurs from thermal fluctuations among different multiplets representing high- and low-spin states. Implications for the Earth will be discussed. [1] Ohta, K., Cohen, R. E., Hirose, K., Haule, K., Shimizu, K. & Ohishi, Y. Experimental and Theoretical Evidence for Pressure-Induced Metallization in FeO with Rocksalt-Type Structure. Phys. Rev. Lett. 108, 026403 (2012).

  6. Fast, real-time, DFT instrument based on VMEbus

    Science.gov (United States)

    Snell, Jay

    An emerging class of VMEbus-based test and measurement instruments is benchmarked by a recently introduced digital spectrum analyzer. The instrument performs real-time spectrum analysis in the DC-to-10 MHz range at 5000 spectrums per second. Its architecture is based on the VMEbus and is partly adapted for high-speed pipeline processing. The keyboard and color graphic displays suit basic spectrum analysis, as well as advanced analysis of amplitude vs. both frequency and time. The instrument provides a DSP (digital signal processing) programming environment when an RS232 terminal is attached. With addition of an RF spectrum analyzer, downconverter, and software, real-time analysis is extended to 21 GHz and beyond. Postprocessable spectral output makes the instrument suitable for use in a larger signal analysis or test system. This digital spectrum analyzer, which has 17 boards on the bus, is representative of an emerging class of filled-enclosure instruments.

  7. Acylation and deacylation mechanism of Helicobacter pylori AmiF formamidase: A computational DFT study

    Science.gov (United States)

    He, Rongxing; Yang, Qinlei; Li, Ming

    2014-04-01

    The acylation and deacylation mechanisms of Helicobacter pylori AmiF formamidase were investigated using DFT method. In the constructed active site, residues Glu60, Glu141 and His167 were taken into account besides Lys133 and Cys166. Calculations provided insight on the details of mechanism and explained crucial roles played by Glu60, Glu141 and His167. For acetylation, we proposed a new stepwise mechanism in which the thiol group first attacks the carbon atom of formamide and produces tetrahedral intermediate. In deacylation, Glu60 activates a water molecule to perform nucleophilic attack and then forms an intermediate, which is different from the usually suggested mechanism.

  8. Natural Carotenoids as Nanomaterial Precursors for Molecular Photovoltaics: A Computational DFT Study

    Directory of Open Access Journals (Sweden)

    Teresita Ruiz-Anchondo

    2010-06-01

    Full Text Available In this work several natural carotenoids were studied as potential nanomaterial precursors for molecular photovoltaics. M05-2X/6-31+G(d,p level of theory calculations were used to obtain their molecular structures, as well as to predict the infrared (IR and ultraviolet (UV-Vis spectra, the dipole moment and polarizability, the pKa, and the chemical reactivity parameters (electronegativity, hardness, electrophilicity and Fukui functions that arise from Conceptual DFT. The calculated values were compared with the available experimental data for these molecules and discussed in terms of their usefulness in describing photovoltaic properties.

  9. Quantum chemical computation by DFT application of NLO molecule 2-aminopyridinium p-toluenesulphonate

    Science.gov (United States)

    Yadav, Mahesh Pal Singh; kumar, Anuj

    2017-07-01

    In the present work, we have reported a theoretical study on molecular structure and vibrational spectra of organic nonlinear optical 2-aminopyridinium p-toluenesulphonate (APPTS). The molecular geometry, electrostatic potential surface and vibrational wave numbers with Raman intensities and infrared absorption intensities in the ground state have been calculated by density functional theory (DFT) method using various basis sets and Beckes three-parameter hybrid functional (B3LYP). Finally, the results were applied to simulate infrared and Raman spectra of the title compound. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis.

  10. Computational Nutraceutics: Chemical Reactivity Properties of the Flavonoid Naringin by Means of Conceptual DFT

    Directory of Open Access Journals (Sweden)

    Jorge Ignacio Martínez-Araya

    2013-01-01

    Full Text Available The M06 family of density functionals has been assessed for the calculation of the molecular structure and properties of the Naringin molecule. The chemical reactivity descriptors have been calculated through Conceptual DFT. The active sites for nucleophilic and electrophilic attacks have been chosen by relating them to the Fukui function indices and the dual descriptor f(2(r. A comparison between the descriptors calculated through vertical energy values and those arising from the Koopmans' theorem approximation has been performed in order to check for the validity of the last procedure.

  11. Determining the structure of Ac-AlanLysH^+ in vacuo: computational spectroscopy using DFT

    Science.gov (United States)

    Rossi, Mariana; Blum, Volker; Kupser, Peter; von Helden, Gert; Bierau, Frauke; Meijer, Gerard; Scheffler, Matthias

    2010-03-01

    Well defined secondary structure motifs (e.g., helices) in polypeptides can be systematically studied in vacuo, offering a unique ``clean room" condition to quantify the stabilizing intramolecular interactions. Here we address theoretically the structure of alanine polypeptides Ac-Alan-LysH^+ (n=5,10,15), for which gas-phase helical structure was indicated in experiment [1]. Using van der Waals (vdW) corrected [2] Density Functional Theory (DFT), we present vibrational spectra and compare to room temperature multiple photon IR spectroscopy data obtained at the FELIX free electron laser. For the longer molecules (n=10,15) α-helical models provide good qualitative agreement (theory vs. experiment) already in the harmonic approximation. For Ac-Ala5LysH^+, the predicted lowest energy conformer (``g-1'') in vdW corrected DFT (PBE, B3LYP, revPBE) is not a simple helix. However, the harmonic free energy suggests that g-1 and the lowest-energy α-helical conformers are energetically close at 300 K, and thus might all coexist in experiment. Consistently, their calculated vibrational spectra agree with experiment, but only if anharmonic effects are included by explicit molecular dynamics simulations. [1] R. Hudgins et al., JACS 120, 12974 (1998) [2] A. Tkatchenko, M. Scheffler, PRL 102, 073005 (2009)

  12. Pyrone-based Cu(II) complexes, their characterization, DFT based conformational drift from square planar to square pyramidal geometry and biological activities

    Indian Academy of Sciences (India)

    Pradeep Kumar Vishwakarma; Jan Mohammad Mir; Ram Charitra Maurya

    2016-04-01

    This work deals with the synthesis and characterization of a series of three -Dehydroacetic acid- 4-phenyl-3-thiosemicarbazide (H2dha-ptsc) Schiff base Cu(II) complexes based on combined experimental and theoretical approach, having the general composition formula as [Cu(dha-ptsc)(L-L)], where L-L is H2O, 2,2-bipyridine (bipy) or 1,10-phenanthroline (phen). H2O containing complex acts as origin for the latter two complexes and in due course, the geometry of the complex changes from square planar to square pyramidal. DFT calculations were carried out for both the geometrical forms. B3LYP/LANL2DZ level of theory was used to carry out the required computations. From the overall DFT computations, square pyramidal geometry was found to be more stable as compared to the square planar conformation for the complexes under investigation. Super oxide dismutation, thermal behaviour and electrochemical activity were also studied. The results have shown satisfactory super oxide scavenging potential, high degree of thermal resistance and efficient redox properties for the title complexes. Moreover, charge analysis and nonlinear optical properties were computed to establish a comprehensive note of atomic constituents differing in nature of charge delocalization.

  13. Computational POM and DFT Evaluation of Experimental in-vitro Cancer Inhibition of Staurosporine-Ruthenium(II) Complexes: the Power Force of Organometallics in Drug Design.

    Science.gov (United States)

    Hadda, Taibi Ben; Genc, Zuhal K; Masand, Vijay H; Nebbache, Nadia; Warad, Ismail; Jodeh, Shehdeh; Genc, Murat; Mabkhot, Yahia N; Barakat, Assem; Salgado-Zamora, Hector

    2015-01-01

    A computational Petra/Osiris/Molinspiration/DFT(POM/DFT) based model has been developed for the identification of physico-chemical parameters governing the bioactivity of ruthenium-staurosporine complexes 2-4 containing an antitumoral-kinase (TK) pharmacophore sites. The four compounds 1-4 analyzed here were previously screened for their antitumor activity, compounds 2 and 4 are neutral, whereas analogue compound 3 is a monocation with ruthenium(II) centre. The highest anti- antitumor activity was obtained for compounds 3 and 4, which exhibited low IC(50) values (0.45 and 8 nM, respectively), superior to staurosporine derivative (pyridocarbazole ligand 1, 150 · 10(3) nM). The IC(50) of 3 (0.45 nM), represents 20,000 fold increased activity as compared to staurosporine derivative 1. The increase of bioactivity could be attributed to the existence of pi-charge transfer from metal-staurosporine to its (CO(δ)--NH(δ+)) antitumor pharmacophore site.

  14. DNA based computers II

    CERN Document Server

    Landweber, Laura F; Baum, Eric B

    1998-01-01

    The fledgling field of DNA computers began in 1994 when Leonard Adleman surprised the scientific community by using DNA molecules, protein enzymes, and chemicals to solve an instance of a hard computational problem. This volume presents results from the second annual meeting on DNA computers held at Princeton only one and one-half years after Adleman's discovery. By drawing on the analogy between DNA computing and cutting-edge fields of biology (such as directed evolution), this volume highlights some of the exciting progress in the field and builds a strong foundation for the theory of molecular computation. DNA computing is a radically different approach to computing that brings together computer science and molecular biology in a way that is wholly distinct from other disciplines. This book outlines important advances in the field and offers comprehensive discussion on potential pitfalls and the general practicality of building DNA based computers.

  15. Molecular Structure, NMR, HOMO, LUMO, and Vibrational Analysis of O-Anisic Acid and Anisic Acid Based on DFT Calculations

    Directory of Open Access Journals (Sweden)

    R. Mathammal

    2013-01-01

    Full Text Available This work deals with the vibrational spectroscopy of O-Anisic acid (OAA and Anisic acid (AA. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT with standard B3LYP/6-31G** method and basis set combinations. The vibrational spectra were interpreted, with the aid of normal coordinate analysis based on a scaled quantum mechanical force field. The infrared and Raman spectra were also predicted from the calculated intensities. The effects of carbonyl and methyl substitutions on the structure and vibrational frequencies have been investigated. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. The 13C and 1H NMR chemical shifts of the DFA and CA molecules were calculated using the gauge-invariant-atomic orbital (GIAO method in DMSO solution using IEF-PCM model and compared with experimental data.

  16. Electron reduction processes of nitrothiophenes. A systematic approach by DFT computations, cyclic voltammetry and E-ESR spectroscopy.

    Science.gov (United States)

    Boga, Carla; Calvaresi, Matteo; Franchi, Paola; Lucarini, Marco; Fazzini, Silvia; Spinelli, Domenico; Tonelli, Domenica

    2012-10-21

    In the framework of the interest in nitrothiophenes as drugs or hits with different pharmacological applications and considering that in several instances nitroreduction is an essential step for their biological activity, we have studied a complete series of mono-, di-, and tri-nitrothiophenes (1-6) and by comparison some mononitro benzo[b]thiophenes and benzo[b]furans (7-10). Their electroreduction behaviour has been investigated by different techniques: DFT calculations, cyclic voltammetry and electrochemical electron spin resonance spectroscopy. Although, the first reduction process for all of the compounds leads to the relevant radical anions, both the computational and experimental results indicate that there are significant differences in the fate of their corresponding forthcoming reductions, for example, formation of secondary radicals (open-shell electronic structures) or dianions. The effect of the relative positions of the nitro groups during the reduction has also been analysed and rationalised.

  17. Comprehensive evaluation of medium and long range correlated density functionals in TD-DFT investigation of DNA bases and base pairs: gas phase and water solution study

    Science.gov (United States)

    Shukla, Manoj K.; Leszczynski, Jerzy

    2010-11-01

    A comprehensive analysis of the performance of the TD-DFT method using different density functionals including recently developed medium and long-range correlation corrected density functionals have been carried out for lower-lying electronic singlet valence transitions of nucleic acid bases and the Watson-Crick base pairs in the gas phase and in the water solution. The standard 6-311++G(d,p) basis set was used. Ground state geometries of bases and base pairs were optimized at the M05-2X/6-311++G(d,p) level. The nature of potential energy surfaces (PES) was ascertained through the harmonic vibrational frequency analysis; all geometries were found to be minima at the respective PES. Electronic singlet vertical transition energies were also computed at the CC2/def2-TZVP level in the gas phase. The effect of state-specific water solvation on TD-DFT computed transition energies was considered using the PCM model. For the isolated bases the performance of the B3LYP functional was generally found to be superior among all functionals, but it measurably fails for charge-transfer states in the base pairs. The CC2/def2-TZVP computed transition energies were also revealed to be inferior compared with B3LYP results for the isolated bases. The performance of the ωB97XD, CAM-B3LYP and BMK functionals were found to be similar and comparable with the CC2 results for the isolated bases. However, for the Watson-Crick adenine-thymine and guanine-cytosine base pairs the performance of the ωB97XD functional was found to be the best among all the studied functionals in the present work in predicting the locally excited transitions as well as charge transfer states.

  18. On Comparison of DFT-Based and DCT-Based Channel Estimation for OFDM System

    Directory of Open Access Journals (Sweden)

    Saqib Saleem

    2011-05-01

    Full Text Available For high data rate communication with the required Quality of Service (QoS in 3G and 4G systems, Orthogonal Frequency Division Multiplexing (OFDM is proposed, which is capable to resist the channel impairments caused by high mobility conditions, by dividing the frequency-selective fading channel into narrowband flat fading channels. In this paper two time-domain channel estimation techniques, Discrete Fourier Transform (DFT and Discrete Cosine Transform (DCT, are compared based on the time-domain channel impulse response (CIR energy characteristics and they have less complexity and efficient performance than Linear Minimum Mean Square Error (LMMSE and Least Square Error (LSE. The effect of power limitation in terms of SNR and the number of multipaths for a wireless channel is determined to compare these transform approaches. Two well known performance criteria: Mean Square Error (MSE and Symbol Error Rate (SER are used for comparison by using Monte Carlo Simulations for Quadrature Phase Shift Keying (QPSK modulation.

  19. Hydration of methanol in water. A DFT-based molecular dynamics study

    CERN Document Server

    Van Erp, T S; Erp, Titus S. van; Meijer, Evert Jan

    2000-01-01

    We studied the hydration of a single methanol molecule in aqueous solution by first-principle DFT-based molecular dynamics simulation. The calculations show that the local structural and short-time dynamical properties of the water molecules remain almost unchanged by the presence of the methanol, confirming the observation from recent experimental structural data for dilute solutions. We also see, in accordance with this experimental work, a distinct shell of water molecules that consists of about 15 molecules. We found no evidence for a strong tangential ordering of the water molecules in the first hydration shell.

  20. A Robust Source Coding Watermark Technique Based on Magnitude DFT Decomposition

    Directory of Open Access Journals (Sweden)

    Sushil Kumar

    2012-07-01

    Full Text Available Image watermarking is considered a powerful tool forCopyright protection, Content authentication, Fingerprintingand for protecting intellectual property. We present in thispaper a watermarking algorithm based on block wise changingmagnitude of DFT domain. This algorithm can be used as anapplication for copyright protection. To provide multi-levelsecurities we have first used best self-synchronizing T-codes toencode the watermark. The encoded watermark is thenembedded into the cover image using a stego-key. We haveanalyzed our algorithm against noise such as Salt and Pepper,Gaussian and Speckle.

  1. Sinusoidal Signal Frequency Estimation Based on Improved DFT Phase Difference%基于改进DFT相位差的正弦波频率估计

    Institute of Scientific and Technical Information of China (English)

    王晓峰; 邢敏捷; 刘歌; 赵汝鹏

    2016-01-01

    The frequency offset sensitivity problem of discrete Fourier transform ( DFT ) phase difference method in sinusoid wave frequency estimation is studied. An improved DFT phase difference frequency esti-mation method is presented. Firstly,the mean-squared error( MSE) of DFT phase difference method is de-duced. And then,an improved DFT phase difference frequency estimation method based on Rife interpola-tion is proposed. The improved method has well solved the problem of sensitivity to frequency offset. The computer simulation results indicate that the improved method has higher estimation accuracy in any fre-quency offset,and its estimation performance is close to Cramer-Rao lower bound( CRLB) .%针对基于离散傅里叶变换( DFT)相位差的正弦波频率估计方法对频偏敏感的问题,提出了一种改进DFT相位差频率估计方法。首先推导了DFT相位差法频率估计的均方误差,然后提出了基于Rife插值的改进DFT相位差频率估计方法,较好地解决了正弦波频率估计对频偏敏感的问题。仿真实验结果表明,改进方法在各种频偏下均能取得较高的估计精度,估计性能接近克拉美罗限( CRLB)。

  2. Partition-based Low Power DFT Methodology for System-on-chips

    Institute of Scientific and Technical Information of China (English)

    LI Yu-fei; CHEN Jian; FU Yu-zhuo

    2007-01-01

    This paper presents a partition-based Design-forTest (DFT) technique to reduce the power consumption during scan-based testing. This method is based on partitioning the chip into several independent scan domains. By enabling the scan domains alternatively, only a fraction of the entire chip will be active at the same time, leading to Iow power consumption during test. Therefore, it will significantly reduce the possibility of Electronic Migration and Overheating. In order to prevent the drop of fault coverage, wrappers on the boundaries between scan domains are employed. This paper also presents a detailed design flow based on Electronics Design Automation(EDA) tools from Synopsy(s) to implement the proposed test structure. The proposed DFT method is experimented on a state-of-theart System-on-chips (SOC). The simulation results show a significant reduction in both average and peak power dissipation without sacrificing the fault coverage and test time. This SOC has been taped out in TSMC and finished the final test in ADVANTEST.

  3. Assessing the density functional theory-based multireference configuration interaction (DFT/MRCI) method for transition metal complexes.

    Science.gov (United States)

    Escudero, Daniel; Thiel, Walter

    2014-05-21

    We report an assessment of the performance of density functional theory-based multireference configuration interaction (DFT/MRCI) calculations for a set of 3d- and 4d-transition metal (TM) complexes. The DFT/MRCI results are compared to published reference data from reliable high-level multi-configurational ab initio studies. The assessment covers the relative energies of different ground-state minima of the highly correlated CrF6 complex, the singlet and triplet electronically excited states of seven typical TM complexes (MnO4(-), Cr(CO)6, [Fe(CN)6](4-), four larger Fe and Ru complexes), and the corresponding electronic spectra (vertical excitation energies and oscillator strengths). It includes comparisons with results from different flavors of time-dependent DFT (TD-DFT) calculations using pure, hybrid, and long-range corrected functionals. The DFT/MRCI method is found to be superior to the tested TD-DFT approaches and is thus recommended for exploring the excited-state properties of TM complexes.

  4. Synthesis, X-ray Structure, Spectroscopic Properties and DFT Studies of a Novel Schiff Base

    Directory of Open Access Journals (Sweden)

    Kew-Yu Chen

    2014-10-01

    Full Text Available A series of Schiff bases, salicylideneaniline derivatives 1–4, was synthesized under mild conditions and characterized by 1H NMR, HRMS, UV-Vis and fluorescence spectra, and single-crystal X-ray diffraction. In solid and aprotic solvents 1–4 exist mainly as E conformers that possess an intramolecular six-membered-ring hydrogen bond. A weak intramolecular C–H×××F hydrogen bond is also observed in fluoro-functionalized Schiff base 4, which generates another S(6 ring motif. The C–H×××F hydrogen bond further stabilizes its structure and leads it to form a planar configuration. Compounds 1–3 exhibit solely a long-wavelength proton-transfer tautomer emission, while dipole-functionalized Schiff base 4 shows remarkable dual emission originated from the excited-state intramolecular charge transfer (ESICT and excited-state intramolecular proton transfer (ESIPT states. Furthermore, the geometric structures, frontier molecular orbitals (MOs and the potential energy curves for 1–4 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT and time-dependent DFT calculations.

  5. Chromium-based rings within the DFT and Falicov-Kimball model approach

    Science.gov (United States)

    Brzostowski, B.; Lemański, R.; Ślusarski, T.; Tomecka, D.; Kamieniarz, G.

    2013-04-01

    We present a comprehensive study of electronic and magnetic properties of octometallic homo- and heteronuclear chromium-based molecular rings Cr7MF8(O2CH)16 (in short Cr7M, M = Cr, Cd and Ni) by the first-principle density functional theory (DFT) and pseudopotential ideas. Their radii are around 1 nm. For each Cr7M, the antiferromagnetic configuration corresponds to the ground state and the ferromagnetic (high spin HS) configuration to the highest energy state. Using the broken symmetry (BS) approach, the differences between the total energies of the HS configuration and all the nonequivalent low spin configurations with s = ±3/2 are calculated and exploited to extract the coupling parameters J between the magnetic ions. Magnetic moments are found to be well localised on the Cr and Ni centres, although the localisation of spin density on Ni is weaker. Having calculated the excess energies for an unprecedented number of configurations, a family of the Ising-like models with the nearest- and the next-nearest-neighbour interactions has been considered. For each Cr7M, the values of the interaction parameters found within the unprojected method are coherent, despite the overdetermination problem and demonstrate that the next-nearest-neighbour couplings are negligible. The DFT estimates of the nearest-neighbour coupling calculated are overestimated and the relation J Cr-Cr/ J Cr-Ni Kimball (FK) model is suggested. In our approach, the effective magnetic interactions between ions are generated by local (on-site) Hund couplings between the ions and itinerant electrons. We demonstrate that the BS state energies obtained within DFT for Cr7M can be successfully represented by the FK model with a unique set of parameters.

  6. Synthesis, structural, DFT studies, docking and antibacterial activity of a xanthene based hydrazone ligand

    Science.gov (United States)

    Naseem, Saira; Khalid, Muhammad; Tahir, Muhammad Nawaz; Halim, Mohammad A.; Braga, Ataualpa A. C.; Naseer, Muhammad Moazzam; Shafiq, Zahid

    2017-09-01

    Herein, we present the synthesis of novel xanthene-based hydrazone (1). The chemical structure of 1 was resolved using spectroscopic techniques such as NMR, FT-IR, UV-VIS and X-ray crystallographic approaches. X-ray diffraction analysis shows that the compound (1) crystallizes in triclinic crystal lattice with the Pbar1 space group and diffused to form multi-layered structure due to non-covalent interactions such as intramolecular hydrogen bonding (H.B). In addition to experimental investigation, density functional theory (DFT) calculation with M06-2X/6-31G(d,p) and B3LYP/6-31G(d,p) level of theories was performed on compound (1) to obtain optimized geometry, spectroscopic and electronic properties. DFT optimized geometry shows good agreement with the experimental XRD structure. The hyper conjugative interactions and hydrogen bonding network are responsible for the stability of compound (1) as revealed by natural bond orbital (NBO) calculation. Moreover, hydrogen bonding network in the dimer is confirmed by FT-IR and thermodynamic studies showing excellent agreement with XRD and NBO findings. TD-DFT/UV-VIS analysis provides insight that maximum excitation is found in 1 which shows good agreement with experimental UV-VIS result. The global reactivity parameters are calculated using the energies of frontier molecular orbitals also disclosed that the compound is more stable might be due to hydrogen bonding network. Experimental and molecular docking studies indicated that this compound has anti-bacterial and anti-diabetic properties. The binding affinity of this compound against the multidrug efflux pump subunit AcrB OS=Escherichia coli (strain K12) and Human Pancreatic Alpha-Amylase is -9.2 and -10.00 kcal/mol which are higher than the control drugs. Pi-Pi, Pi-anaion, amide-pi and pi-alkyl bonds play key role in drug-protein complexes.

  7. DFT computational study on decarboxylation mechanism of salicylic acid and its derivatives in the anionic state

    Science.gov (United States)

    Gao, Lu; Hu, Yanying; Zhang, Huitu; Liu, Yanchun; Song, Zhidan; Dai, Yujie

    2016-07-01

    The mechanisms of the decarboxylation of salicylic acid anion and its ortho substituted derivatives in gas phase and aqueous solution have been investigated by B3LYP method of DFT theory using the 6-31++G (d,p) basis set. The decarboxylation process includes hydrogen transfers from hydroxyl to carboxyl group and from carboxyl to the α-C of the aryl ring. The mechanism suggested is a pseudo-unimolecular decomposition of the salicylic acid anion and the hydrogen transfer from carboxyl to the α-C of the aryl ring is the rate determining step. Compared with the decarboxylation process in gas phase, the energy barriers in aqueous solution approximately declined by 25%-31%with the water mediation of the hydrogen transfer from carboxyl to the α-C of the aryl ring. The effects of substituents at the ortho position on the decarboxylation process were also investigated. Both the electron donating CH3 and withdrawing group NO2 at the ortho position of carboxyl group can further reduce the reaction energy barriers of the decarboxylation of salicylic acid anions.

  8. ANI-1: An extensible neural network potential with DFT accuracy at force field computational cost

    CERN Document Server

    Smith, Justin S; Roitberg, Adrian E

    2016-01-01

    Deep learning is revolutionizing many areas of science and technology, especially image, text and speech recognition. In this paper, we demonstrate how a deep neural network (NN) trained on quantum mechanical (QM) DFT calculations can learn an accurate and fully transferable potential for organic molecules. We introduce ANAKIN-ME (Accurate NeurAl networK engINe for Molecular Energies) or ANI in short. ANI is a new method and procedure for training neural network potentials that utilizes a highly modified version of the Behler and Parrinello symmetry functions to build single-atom atomic environment vectors as a molecular representation. We utilize ANI to build a potential called ANI-1, which was trained on a subset of the GDB databases with up to 8 heavy atoms to predict total energies for organic molecules containing four atom types: H, C, N, and O. To obtain an accelerated but physically relevant sampling of molecular potential surfaces, we also propose a Normal Mode Sampling (NMS) method for generating mol...

  9. Intramolecular Hydrogen Bonding Involving Organic Fluorine: NMR Investigations Corroborated by DFT-Based Theoretical Calculations

    Directory of Open Access Journals (Sweden)

    Sandeep Kumar Mishra

    2017-03-01

    Full Text Available The combined utility of many one and two dimensional NMR methodologies and DFT-based theoretical calculations have been exploited to detect the intramolecular hydrogen bond (HB in number of different organic fluorine-containing derivatives of molecules, viz. benzanilides, hydrazides, imides, benzamides, and diphenyloxamides. The existence of two and three centered hydrogen bonds has been convincingly established in the investigated molecules. The NMR spectral parameters, viz., coupling mediated through hydrogen bond, one-bond NH scalar couplings, physical parameter dependent variation of chemical shifts of NH protons have paved the way for understanding the presence of hydrogen bond involving organic fluorine in all the investigated molecules. The experimental NMR findings are further corroborated by DFT-based theoretical calculations including NCI, QTAIM, MD simulations and NBO analysis. The monitoring of H/D exchange with NMR spectroscopy established the effect of intramolecular HB and the influence of electronegativity of various substituents on the chemical kinetics in the number of organic building blocks. The utility of DQ-SQ technique in determining the information about HB in various fluorine substituted molecules has been convincingly established.

  10. Channel estimation in DFT-based offset-QAM OFDM systems.

    Science.gov (United States)

    Zhao, Jian

    2014-10-20

    Offset quadrature amplitude modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) exhibits enhanced net data rates compared to conventional OFDM, and reduced complexity compared to Nyquist FDM (N-FDM). However, channel estimation in discrete-Fourier-transform (DFT) based offset-QAM OFDM is different from that in conventional OFDM and requires particular study. In this paper, we derive a closed-form expression for the demultiplexed signal in DFT-based offset-QAM systems and show that although the residual crosstalk is orthogonal to the decoded signal, its existence degrades the channel estimation performance when the conventional least-square method is applied. We propose and investigate four channel estimation algorithms for offset-QAM OFDM that vary in terms of performance, complexity, and tolerance to system parameters. It is theoretically and experimentally shown that simple channel estimation can be realized in offset-QAM OFDM with the achieved performance close to the theoretical limit. This, together with the existing advantages over conventional OFDM and N-FDM, makes this technology very promising for optical communication systems.

  11. Complementary study based on DFT to describe the structure and properties relationship of diblock copolymer based on PVK and PPV

    Energy Technology Data Exchange (ETDEWEB)

    Mbarek, M.; Abbassi, F.; Alimi, K., E-mail: kamel.alimi@fsm.rnu.tn

    2016-09-15

    The structure-properties relationships of copolymer involving N-vinylcarbazole (PVK) and poly (p-phenylene-vinylene) (PPV) blocks, denoted PVK–PPV, was investigated by calculations based on density functional theory (DFT) and completed by experimental analyses. Thus, vibrational, optical and emission spectra of model compound have been simulated and compared to the experiments observations published recently. Ionization potentials (IPs), electron affinities (EAs) and energy gaps were determined. Furthermore, quantum yields, radiative and nonradiative exciton lifetime was highlighted.

  12. Synthesis of novel styryl derivatives from 4-chloro-2-(morpholin-4-yl)-1,3-thiazole-5-carbaldehyde, study of their photophysical properties and TD-DFT computations

    Energy Technology Data Exchange (ETDEWEB)

    Sekar, Nagaiyan, E-mail: n.sekar@ictmumbai.edu.in [Tinctorial Chemistry Group, Institute of Chemical Technology, Matunga, Mumbai 400019 (India); Umape, Prashant G.; Padalkar, Vikas S.; Tayade, Rajratna P. [Tinctorial Chemistry Group, Institute of Chemical Technology, Matunga, Mumbai 400019 (India); Ramasami, Ponnadurai [Computational Chemistry Group, Department of Chemistry, Faculty of Science, University of Mauritius, Réduit (Mauritius)

    2014-06-01

    Novel fluorescent styryl push–pull compounds having electron donating thiazole unit were synthesized by condensing 4-chloro-2-(morpholin-4-yl)-1,3-thiazole-5-carbaldehyde with active methylene compounds via classical Knoevenagel condensation. The synthesized styryl molecules were characterized by spectral analysis. Photophysical properties of these styryl derivatives were analyzed and the effect of change in solvent polarity and viscosity on their absorptive and emissive properties has been investigated. Density functional theory (DFT) and time dependent-density functional theory (TD-DFT) computations have been used to understand the structural, molecular, electronic and photophysical parameters of push–pull dyes. Bakhshiev and Kawski–Chamma–Viallet correlations were used to calculate the ratio of ground to excited state dipole moment of the synthesized novel styryl compounds. -- Highlights: •Novel styryl derivatives are synthesized from thiazole aldehyde. •Photophysical properties of styryl derivatives were evaluated and supported by TD-DFT computations. •Experimental photophysical results are in good agreement with the theoretical results obtained by TD-DFT computations. •Compounds show fluorescence in solid state as well as in solvents of different polarities.

  13. DFT-based QSAR and QSPR models of several cis-platinum complexes: solvent effect.

    Science.gov (United States)

    Sarmah, Pubalee; Deka, Ramesh C

    2009-06-01

    Cytotoxic activities of cis-platinum complexes against parental and resistant ovarian cancer cell lines were investigated by quantitative structure-activity relationship (QSAR) analysis using density functional theory (DFT) based descriptors. The calculated parameters were found to increase the predictability of each QSAR model with incorporation of solvent effects indicating its importance in studying biological activity. Given the importance of logarithmic n-octanol/water partition coefficient (log P(o/w)) in drug metabolism and cellular uptake, we modeled the log P(o/w) of 24 platinum complexes with different leaving and carrier ligands by the quantitative structure-property relationship (QSPR) analysis against five different concentrations of MeOH using DFT and molecular mechanics derived descriptors. The log P(o/w) values of an additional set of 20 platinum complexes were also modeled with the same descriptors. We investigated the predictability of the model by calculating log P(o/w) of four compounds in the test set and found their predicted values to be in good agreement with the experimental values. The QSPR analyses performed on 24 complexes, combining the training and test sets, also provided significant values for the statistical parameters. The solvent medium played an important role in QSPR analysis by increasing the internal predictive ability of the models.

  14. Analyzing the validity of a DFT-based improved acoustic OFDM transmission along rotating simulated drillstring

    Science.gov (United States)

    Cheng, Li; Jinfeng, Chang; Shangchun, Fan; Jun, Yang

    2016-12-01

    In the oil industry, drillstring can be used as a transmission medium to send downhole information via a modulated compressional acoustic wave. However, the accompanied reverberation is a major constraint in the transmission rate and distance because of the multipath fading caused by the heterogeneous drillstring. In combination with discrete Fourier transform-spread (DFT-S) mapping/demapping, high-power amplitude squeezing and DFT-based least squares channel estimation methods, an improved orthogonal frequency division multiplexing (OFDM) scheme is proposed in this paper to overcome the symbol interference inherent in the drillstring multipath channel and reduce the peak-to-average power ratio of the signal. Then an experimental rig is established by using a rotatable electromagnetic vibration exciter and a piezoelectric accelerometer arranged at the position closer to acoustic impedance terminal along a 6.3-m periodic simulated drillstring. The OFDM data sequences at a data rate of 200 bit/s over a limited bandwidth of 140 Hz are applied to the rotating simulated drillstring. The experimental results show that the proposed scheme using QPSK modulation can offer an error-free acoustic communication at rotation speeds up to 90 r/min.

  15. Optical Absorption and Electron Injection of 4-(Cyanomethylbenzoic Acid Based Dyes: A DFT Study

    Directory of Open Access Journals (Sweden)

    Yuehua Zhang

    2015-01-01

    Full Text Available Density functional theory (DFT and time-dependent density functional theory (TDDFT calculations were carried out to study the ground state geometries, electronic structures, and absorption spectra of 4-(cyanomethylbenzoic acid based dyes (AG1 and AG2 used for dye-sensitized solar cells (DSSCs. The excited states properties and the thermodynamical parameters of electron injection were studied. The results showed that (a two dyes have uncoplanar structures along the donor unit and conjugated bridge space, (b two sensitizers exhibited intense absorption in the UV-Vis region, and (c the excited state oxidation potential was higher than the conduction band edge of TiO2 photoanode. As a result, a solar cell based on the 4-(cyanomethylbenzoic acid based dyes exhibited well photovoltaic performance. Furthermore, nine dyes were designed on the basis of AG1 and AG2 to improve optical response and electron injection.

  16. A DFT-based QSAR study on inhibition of human dihydrofolate reductase.

    Science.gov (United States)

    Karabulut, Sedat; Sizochenko, Natalia; Orhan, Adnan; Leszczynski, Jerzy

    2016-11-01

    Diaminopyrimidine derivatives are frequently used as inhibitors of human dihydrofolate reductase, for example in treatment of patients whose immune system are affected by human immunodeficiency virus. Forty-seven dicyclic and tricyclic potential inhibitors of human dihydrofolate reductase were analyzed using the quantitative structure-activity analysis supported by DFT-based and DRAGON-based descriptors. The developed model yielded an RMSE deviation of 1.1 a correlation coefficient of 0.81. The prediction set was characterized by R(2)=0.60 and RMSE=3.59. Factors responsible for inhibition process were identified and discussed. The resulting model was validated via cross validation and Y-scrambling procedure. From the best model, we found several mass-related descriptors and Sanderson electronegativity-related descriptors that have the best correlations with the investigated inhibitory concentration. These descriptors reflect results from QSAR studies based on characteristics of human dihydrofolate reductase inhibitors.

  17. Computer based satellite design

    Science.gov (United States)

    Lashbrook, David D.

    1992-06-01

    A computer program to design geosynchronous spacecraft has been developed. The program consists of four separate but interrelated executable computer programs. The programs are compiled to run on a DOS based personnel computer. The source code is written in DoD mandated Ada programming language. The thesis presents the design technique and design equations used in the program. Detailed analysis is performed in the following areas for both dual spin and three axis stabilized spacecraft configurations: (1) Mass Propellent Budget and Mass Summary; (2) Battery Cell and Solar Cell Requirements for a Payload Power Requirement; and (3) Passive Thermal Control Requirements. A user's manual is included as Appendix A, and the source code for the computer programs as Appendix B.

  18. Structure and spectroscopy of water-fluoride microclusters: a combined genetic algorithm and DFT-based study.

    Science.gov (United States)

    Neogi, Soumya Ganguly; Chaudhury, Pinaki

    2012-03-05

    In this article, we explore the efficiency of using a coupled genetic algorithm (GA) and density functional theory (DFT) based strategy to evaluate probable structures of (H(2) O)(n) F(-) micro-clusters, with n = 1 - 6. We use the stochastic optimization technique of GA to arrive at structures of the cluster systems and once the structures are obtained, do a DFT calculation with the optimized coordinates from the GA calculation as input to get the infra-red spectrum of all the systems. The results of our work closely resembles the pure quantum chemical results obtained by Baik et al. (J Chem Phys 1999, 110, 9116-9127).

  19. Density functional theory (DFT)-based modified embedded atom method potentials: Bridging the gap between nanoscale theoretical simulations and DFT calculations

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A density functional theory (DFT)-calculation scheme for constructing the modified embedded atom method (MEAM) potentials for face-centered cubic (fcc) metals is presented. The input quantities are carefully selected and a more reliable DFT approach for surface energy determination is introduced in the parameterization scheme, enabling MEAM to precisely predict the surface and nanoscale properties of metallic materials. Molecular dynamics simulations on Pt and Au crystals show that the parameterization employed leads to significantly improved accuracy of MEAM in calculating the surface and nanoscale properties, with the results agreeing well with both DFT calculations and experimental observations. The present study implies that rational DFT parameterization of MEAM may lead to a theoretical tool to bridge the gap between nanoscale theoretical simulations and DFT calculations.

  20. SU-C-204-03: DFT Calculations of the Stability of DOTA-Based-Radiopharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Khabibullin, A.R.; Woods, L.M. [University of South Florida, Tampa, Florida (United States); Karolak, A.; Budzevich, M.M.; Martinez, M.V. [H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida (United States); McLaughlin, M.L.; Morse, D.L. [University of South Florida, Tampa, Florida (United States); H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida (United States)

    2016-06-15

    Purpose: Application of the density function theory (DFT) to investigate the structural stability of complexes applied in cancer therapy consisting of the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelated to Ac225, Fr221, At217, Bi213, and Gd68 radio-nuclei. Methods: The possibility to deliver a toxic payload directly to tumor cells is a highly desirable aim in targeted alpha particle therapy. The estimation of bond stability between radioactive atoms and the DOTA chelating agent is the key element in understanding the foundations of this delivery process. Thus, we adapted the Vienna Ab-initio Simulation Package (VASP) with the projector-augmented wave method and a plane-wave basis set in order to study the stability and electronic properties of DOTA ligand chelated to radioactive isotopes. In order to count for the relativistic effect of radioactive isotopes we included Spin-Orbit Coupling (SOC) in the DFT calculations. Five DOTA complex structures were represented as unit cells, each containing 58 atoms. The energy optimization was performed for all structures prior to calculations of electronic properties. Binding energies, electron localization functions as well as bond lengths between atoms were estimated. Results: Calculated binding energies for DOTA-radioactive atom systems were −17.792, −5.784, −8.872, −13.305, −18.467 eV for Ac, Fr, At, Bi and Gd complexes respectively. The displacements of isotopes in DOTA cages were estimated from the variations in bond lengths, which were within 2.32–3.75 angstroms. The detailed representation of chemical bonding in all complexes was obtained with the Electron Localization Function (ELF). Conclusion: DOTA-Gd, DOTA-Ac and DOTA-Bi were the most stable structures in the group. Inclusion of SOC had a significant role in the improvement of DFT calculation accuracy for heavy radioactive atoms. Our approach is found to be proper for the investigation of structures with DOTA-based

  1. A DFT-based genetic algorithm search for AuCu nanoalloy electrocatalysts for CO2 reduction

    DEFF Research Database (Denmark)

    Lysgaard, Steen; Mýrdal, Jón Steinar Garðarsson; Hansen, Heine Anton

    2015-01-01

    Using a DFT-based genetic algorithm (GA) approach, we have determined the most stable structure and stoichiometry of a 309-atom icosahedral AuCu nanoalloy, for potential use as an electrocatalyst for CO2 reduction. The identified core–shell nano-particle consists of a copper core interspersed...

  2. Assessment of Charge-Transfer Excitations in Organic Dyes obtained from TD-srDFT Based on Long-Range MP2 and MCSCF Wave Functions

    CERN Document Server

    Hedegård, Erik D; Knecht, Stefan; Fromager, Emmanuel; Jensen, Hans Jørgen Aa

    2013-01-01

    Charge transfer excitations can be described within TD-DFT, not only by means of long-range corrected exchange functionals but also with a combination of wave function theory and TD-DFT based on range separation. The latter approach enables a rigorous formulation of multi-determinantal TD-DFT schemes where excitation classes, which are absent in conventional TD-DFT spectra (like for example double excitations), can be addressed. This paper investigates the combination of both the long-range MCSCF and SOPPA ans\\"atze with a short-range DFT (srDFT) description. We find that the combinations of SOPPA or MCSCF with TD-DFT yield better results than could be expected from the pure wave function schemes. For the Time-Dependent MCSCF short-range DFT ansatz (TD-MC-srDFT) excitation energies calculated over a larger benchmark set of molecules with predominantly single reference character yield good agreement with their reference values, and are in general comparable to the long-range corrected functional CAM-B3LYP. The...

  3. Spintronics-based computing

    CERN Document Server

    Prenat, Guillaume

    2015-01-01

    This book provides a comprehensive introduction to spintronics-based computing for the next generation of ultra-low power/highly reliable logic, which is widely considered a promising candidate to replace conventional, pure CMOS-based logic. It will cover aspects from device to system-level, including magnetic memory cells, device modeling, hybrid circuit structure, design methodology, CAD tools, and technological integration methods. This book is accessible to a variety of readers and little or no background in magnetism and spin electronics are required to understand its content.  The multidisciplinary team of expert authors from circuits, devices, computer architecture, CAD and system design reveal to readers the potential of spintronics nanodevices to reduce power consumption, improve reliability and enable new functionality.  .

  4. Improving Performance and Versatility of Systems Based on Single-Frequency DFT Detectors Such as AD5933

    Directory of Open Access Journals (Sweden)

    Leonid Matsiev

    2014-12-01

    Full Text Available Turning grand concepts such as the Internet of Things (IoT and Smart Cities into reality requires the development and deployment of a wide variety of computing devices incorporated into the Internet infrastructure. Unsupervised sensing is the cornerstone capability that these devices must have to perform useful functions, while also having low cost of acquisition and ownership, little energy consumption and a small footprint. Impedimetric sensing systems based on the so-called single-frequency DFT detectors possess many of these desirable attributes and are often introduced in remote monitoring and wearable devices. This study presents new methods of improving performance of such detectors. It demonstrates that the main source of systematic errors is the discontinuous test phasor causing the crosstalk between the in-phase and quadrature outputs and the leakage of the input signal. The study derives expressions for these errors as a function of the number of samples and operating frequency, and provides methods for correction. The proposed methods are applied to the operation of a practical device—a network analyzer integrated circuit AD5933—and discussed in detail. These methods achieve complete elimination of leakage errors and expansion of the low limit of the operation frequency range by nearly two decades without additional hardware.

  5. DFT-based inhibitor and promoter selection criteria for pentagonal dodecahedron methane hydrate cage

    Indian Academy of Sciences (India)

    Snehanshu Pal; T K Kundu

    2013-09-01

    Density functional theory (DFT)-based simulations have been performed to provide electronic structure property correlation based reasoning for conceptualizing the effect of encapsulated methane molecule on the formation of methane hydrate cages, the role of methanol and ethylene glycol as inhibitor and the role of tetra-hydro-furan (THF) and cyclopentane as promoter of methane hydrate. Geometry optimization of 512 cage, 51262 cage and 51264 cage with and without encapsulated methane and the cluster of 512 cage with ethylene glycol, methanol, cyclopentane have been performed by density functional theory using B97X-D/6-31++G(d,p) method. Methane hydrate formation inhibition by methanol and ethylene glycol as well as methane hydrate stabilization by cyclopentane and tetrahydrofuran are critically analysed based on the interaction energy, free energy change, dipole moment and infrared frequency calculation. Calculation of free energy change for formation of methane hydrate with/without reagents at various temperature and pressure using optimized structure is reported here. It is observed that hydrogen bond between water molecules of clathrate 512 cages become stronger in the presence of cyclopentane and tetrahydrofuran but weaker/broken in the presence of ethylene glycol and methanol. Simulated results correspond well with experimental findings and can be useful for designing new inhibitor and promoter molecules for gas hydrate formation.

  6. Predictions of Physicochemical Properties of Ionic Liquids with DFT

    Directory of Open Access Journals (Sweden)

    Karl Karu

    2016-07-01

    Full Text Available Nowadays, density functional theory (DFT-based high-throughput computational approach is becoming more efficient and, thus, attractive for finding advanced materials for electrochemical applications. In this work, we illustrate how theoretical models, computational methods, and informatics techniques can be put together to form a simple DFT-based throughput computational workflow for predicting physicochemical properties of room-temperature ionic liquids. The developed workflow has been used for screening a set of 48 ionic pairs and for analyzing the gathered data. The predicted relative electrochemical stabilities, ionic charges and dynamic properties of the investigated ionic liquids are discussed in the light of their potential practical applications.

  7. Characteristics of Interlayer Tunneling Field-Effect Transistors Computed by a "DFT-Bardeen" Method

    Science.gov (United States)

    Li, Jun; Nie, Yifan; Cho, Kyeongjae; Feenstra, Randall M.

    2017-02-01

    Theoretical predictions have been made for the current-voltage characteristics of two-dimensional heterojunction interlayer tunneling field-effect transistors (Thin-TFETs), focusing on the magnitude of the current achievable in such devices. A theory based on the Bardeen tunneling method is employed, using wavefunctions obtained from first-principles density functional theory. This method permits convenient incorporation of differing materials into the source and drain electrodes, i.e., with different crystal structure, lattice constants, and/or band structure. Large variations in tunneling current are found, depending on the two-dimensional materials used for the source and drain electrodes. Tunneling between states derived from the center (Γ-point) of the Brillouin zone (BZ) is found, in general, to lead to larger current than for zone-edge (e.g., K-point) states. The differences, as large as an order of magnitude, between the present results and various prior predictions are discussed. Predicted values for the tunneling current, including the subthreshold swing, are compared with benchmark values for low-power digital applications. Contact resistance is considered, and its effect on the tunneling current demonstrated.

  8. Semiempirical and DFT computations of the influence of Tb(III) dopant on unit cell dimensions of cerium(III) fluoride.

    Science.gov (United States)

    Shyichuk, Andrii; Runowski, Marcin; Lis, Stefan; Kaczkowski, Jakub; Jezierski, Andrzej

    2015-01-30

    Several computational methods, both semiempirical and ab initio, were used to study the influence of the amount of dopant on crystal cell dimensions of CeF3 doped with Tb(3+) ions (CeF3 :Tb(3+) ). AM1, RM1, PM3, PM6, and PM7 semiempirical parameterization models were used, while the Sparkle model was used to represent the lanthanide cations in all cases. Ab initio calculations were performed by means of GGA+U/PBE projector augmented wave density functional theory. The computational results agree well with the experimental data. According to both computation and experiment, the crystal cell parameters undergo a linear decrease with increasing amount of the dopant. The computations performed using Sparkle/PM3 and DFT methods resulted in the best agreement with the experiment with the average deviation of about 1% in both cases. Typical Sparkle/PM3 computation on a 2×2×2 supercell of CeF3:Tb3+ lasted about two orders of magnitude shorter than the DFT computation concerning a unit cell of this material. © 2014 Wiley Periodicals, Inc.

  9. DFT-based prediction of reactivity of short-chain alcohol dehydrogenase

    Science.gov (United States)

    Stawoska, I.; Dudzik, A.; Wasylewski, M.; Jemioła-Rzemińska, M.; Skoczowski, A.; Strzałka, K.; Szaleniec, M.

    2017-06-01

    The reaction mechanism of ketone reduction by short chain dehydrogenase/reductase, ( S)-1-phenylethanol dehydrogenase from Aromatoleum aromaticum, was studied with DFT methods using cluster model approach. The characteristics of the hydride transfer process were investigated based on reaction of acetophenone and its eight structural analogues. The results confirmed previously suggested concomitant transfer of hydride from NADH to carbonyl C atom of the substrate with proton transfer from Tyr to carbonyl O atom. However, additional coupled motion of the next proton in the proton-relay system, between O2' ribose hydroxyl and Tyr154 was observed. The protonation of Lys158 seems not to affect the pKa of Tyr154, as the stable tyrosyl anion was observed only for a neutral Lys158 in the high pH model. The calculated reaction energies and reaction barriers were calibrated by calorimetric and kinetic methods. This allowed an excellent prediction of the reaction enthalpies (R2 = 0.93) and a good prediction of the reaction kinetics (R2 = 0.89). The observed relations were validated in prediction of log K eq obtained for real whole-cell reactor systems that modelled industrial synthesis of S-alcohols.

  10. Adsorption performance of Rh decorated SWCNT upon SF6 decomposed components based on DFT method

    Science.gov (United States)

    Zhang, Xiaoxing; Cui, Hao; Dong, Xingchen; Chen, Dachang; Tang, Ju

    2017-10-01

    Transition metal decorated carbon nanotubes (CNTs) applied in the field of gas adsorption and storage have in recent years accepted considerable attentions because of their superior adsorbing performance. In electrical engineering, they are employed as adsorbents to remove the decomposed products of SF6 caused by partial discharge, for guaranteeing the insulation status of gas insulation switchgear (GIS). In this paper, Rh doped SWCNT is introduced to investigate its adsorption properties towards typical gases of SF6 based on density functional theory (DFT) method. Both single and double molecules adsorbing systems were performed to investigate the adsorption ability of proposed material. Results indicate that Rh-CNT, which has strong interaction with defined gas molecules, is a promising material for SF6 decompositions adsorption especially SO2 and SOF2 that exhibit topmost sensitivity to the modified surface. Therefore, we suggest the Rh-CNT to be an adsorbent to be applied in GIS for guaranteeing the operation state of such devices and even to be exploited as gas sensor to evaluate the insulation state of the power system. Our calculations would provide experimentalist with a first insight into physicochemical properties of this material.

  11. Charge Density Analysis and Transport Properties of TTF Based Molecular Nanowires: A DFT Approach

    Directory of Open Access Journals (Sweden)

    Karuppannan Selvaraju

    2015-01-01

    Full Text Available The present study has been performed to understand the charge density distribution and the electrical characteristics of Au and thiol substituted tetrathiafulvalene (TTF based molecular nanowire. A quantum chemical calculation has been carried out using DFT method (B3LYP with the LANL2DZ basis set under various applied electric fields (EFs. The bond topological analysis characterizes the terminal Au–S and S–C bonds as well as all the bonds of central TTF unit of the molecule. The variation of electron density and Laplacian of electron density at the bond critical point of bonds for zero and different applied fields reveal the electron density distribution of the molecule. The molecular conformation, the variation of atomic charges and energy density distribution of the molecule have been analyzed for the various levels of applied EFs. The HOMO-LUMO gap calculated from quantum chemical calculations has been compared with the value calculated from the density of states. The variation of dipole moment due to the polarization effect and the I-V characteristics of the molecule for the various applied EFs have been well discussed.

  12. DFT-based Theoretical Calculation of Nb- and W-doped Anatase TiO2

    Science.gov (United States)

    Suenaga, Takahiro; Kamisaka, Hideyuki; Nakamura, Hisao; Yamashita, Koichi

    2010-03-01

    The structure and electronic states in the Nb-doped TiO2 (TNO) and W-doped TiO2 (TWO) in anatase phase were investigated from the first-principle using DFT-based band structure method. In addition to the cases where the dopant substituting a Ti atom, cells containing a dopant (MTi; M = Nb, W) and an oxygen vacancy (VO) were calculated in order to clarify the role of the oxygen vacancy in the system. Furthermore, cells containing two dopants and an oxygen vacancy (2MTi--VO), and cells with a dopant and two oxygen vacancies (MTi--2VO) were calculated. Energetically stable structures were found among the sampled 2WTi--VO and WTi--2VO cells, while the corresponding structures in TNO did not show any significant energy stabilization. Impurity states were found in the stable 2WTi--VO and WTi--2VO structures, and an approach of the two WTi atoms was observed in the former. The present results rationalize the lower electronic conductivity of TWO than that of TNO, and suggest possible formation of complex structures consisting of the WTi dopants and the oxygen vacancies.

  13. Diaminomaleonitrile-based azo receptors: Synthesis, DFT studies and their antibacterial activities

    Science.gov (United States)

    Khanmohammadi, Hamid; Arab, Vajihe; Rezaeian, Khatereh; Talei, Gholam Reza; Pass, Maryam; Shabani, Nafiseh

    2017-02-01

    New unsymmetric diaminomaleonitrile-based azo receptors (H3Ln, n = 1-3) have been synthesized via condensation reaction of 5-(4-X-phenyl)-azo-salicyladehyde (X = NO2, OMe and CH3) with 2-amino-3-(5-bromo-2-hydroxybenzylamino)maleonitrile. The solvatochromic behaviors of the molecules were probed by studying their UV-Vis spectra in five pure organic solvents of different polarities. The p-NO2 substituted receptor shows a dramatic color change from yellow to blue upon the addition of fluoride ion in CH3CN. This capability was studied by systematic TD-DFT calculations. These compounds were assayed for their in vitro antibacterial activities against Gram-positive (S. aureus, S. epidermidis and L. monocytogenes) and Gram-negative (E. coli, P. aeruginosa and K. pneumonia.) bacteria by disc diffusion method. The results indicated that the compounds show good inhibition against Gram positive bacteria namely L. monocytogenes as compared to standard drugs.

  14. Predictive DFT-based approaches to charge and spin transport in single-molecule junctions and two-dimensional materials: successes and challenges.

    Science.gov (United States)

    Quek, Su Ying; Khoo, Khoong Hong

    2014-11-18

    CONSPECTUS: The emerging field of flexible electronics based on organics and two-dimensional (2D) materials relies on a fundamental understanding of charge and spin transport at the molecular and nanoscale. It is desirable to make predictions and shine light on unexplained experimental phenomena independently of experimentally derived parameters. Indeed, density functional theory (DFT), the workhorse of first-principles approaches, has been used extensively to model charge/spin transport at the nanoscale. However, DFT is essentially a ground state theory that simply guarantees correct total energies given the correct charge density, while charge/spin transport is a nonequilibrium phenomenon involving the scattering of quasiparticles. In this Account, we critically assess the validity and applicability of DFT to predict charge/spin transport at the nanoscale. We also describe a DFT-based approach, DFT+Σ, which incorporates corrections to Kohn-Sham energy levels based on many-electron calculations. We focus on single-molecule junctions and then discuss how the important considerations for DFT descriptions of transport can differ in 2D materials. We conclude that when used appropriately, DFT and DFT-based approaches can play an important role in making predictions and gaining insight into transport in these materials. Specifically, we shall focus on the low-bias quasi-equilibrium regime, which is also experimentally most relevant for single-molecule junctions. The next question is how well can the scattering of DFT Kohn-Sham particles approximate the scattering of true quasiparticles in the junction? Quasiparticles are electrons (holes) that are surrounded by a constantly changing cloud of holes (electrons), but Kohn-Sham particles have no physical significance. However, Kohn-Sham particles can often be used as a qualitative approximation to quasiparticles. The errors in standard DFT descriptions of transport arise primarily from errors in the Kohn-Sham energy levels

  15. Strategies toward the Total Synthesis of Calyciphylline B-type Alkaloids: A Computational Perspective Aided by DFT Analysis.

    Science.gov (United States)

    Chattopadhyay, Amit Kumar; Berger, Gilles; Hanessian, Stephen

    2016-06-17

    Herein we describe synthetic efforts toward the total synthesis of calyciphylline B-type alkaloids. In the process, we disclose a detailed DFT study of equilibrium geometries and transition states that explains the stereochemical outcome during the formation of critical intermediates. X-ray crystallographic analysis reveals interesting conformational features in the naturally occurring deoxycalyciphylline B and its synthetic congeners.

  16. A DFT Scheme for Pneumatic Control Logic in Flow-based Biochips

    DEFF Research Database (Denmark)

    Potluri, Seetal; Pop, Paul; Madsen, Jan

    2016-01-01

    in turn control the fluidic operations, it is very important that they are fault-free, in order to avoid the failure of biochemical applications. For the first time, this paper proposes a design-for-testability (DFT) scheme to test for faults inside on-chip pneumatic control logic circuits, by adding...... observation pneumatic latches into the circuit. We show that the problem of attaining high fault coverage by adding minimum number of observation pneumatic latches, is an instance of the set cover problem, which is NP-hard. We use a greedy set cover algorithm and show that our DFT scheme attains a fault...

  17. First principles and DFT supported investigations on vibrational spectra and electronic structure of 2-((phenylamino)methyl)isoindoline-1,3-dione - An antioxidant active Mannich base

    Science.gov (United States)

    Boobalan, Maria susai; Amaladasan, M.; Ramalingam, S.; Tamilvendan, D.; Venkatesa Prabhu, G.; Bououdina, M.

    2015-02-01

    The 2-((phenylamino)methyl)isoindoline-1,3-dione (PID) is a synthesized Mannich base which has significant antioxidant activity and biological importance. Quantum mechanical calculations on energy, geometry and vibrational wavenumber of PID were computed using ab initio HF and density functional theory (DFT/B3LYP) methods with 6-31+G/6-311++G(d,p) basis sets. Optimized geometrical parameters obtained by HF and DFT calculations were indicatively agreement with experimental crystal geometry. The experimental FT-Raman and FT-IR spectra of PID has been recorded and analyzed by comparing with simulated spectra. The 1H and 13C NMR spectra of title molecule records the chemical shift resulted from shielding and deshielding effects. Natural bond orbital (NBO) analysis has been carried out to calculate various intramolecular interactions that are accountable for the stabilization of this Mannich base. The predicted HOMO-LUMO gap offers interesting information on intramolecular charge transfer and reactivity of the molecular system. Molecular electrostatic potential (MEP) imprint visualize the reactive sites in PID, which is also supported by Mulliken, ESP, Hirshfeld and NBO charges. Thermodynamic properties of PID at various temperatures have been calculated at B3LYP/6-311++G(d,p) in gas phase and the correlations between standard entropies (S), internal energy (E or U) and standard heat capacity (C) with different temperatures.

  18. Towards the design of cyclooxygenase (COX) inhibitors based on 4',5 di-substituted biphenyl acetic acid molecules: a QSAR study with a new DFT based descriptor - nucleus independent chemical shift.

    Science.gov (United States)

    Sarkar, Ananda; Mostafa, Golam

    2009-10-01

    Cyclooxygenase (COX) is a well-known enzyme, which converts arachidonic acid to prostaglandins H(2) (PGH(2)), which are the effective mediators of inflammation. 4', 5 di-substituted 3-biphenyl acetic acids (BPA) and several alpha-methyl derivatives (MBPA) of it are widely used as powerful nonsteroidal anti-inflammatory and analgesic agents. We have chosen these activity data because the relation between the substituents and activity is not obvious and is hard to explain and also to show the superiority of DFT method. From the DFT results, various quantum chemical based descriptors were computed but the QSAR results showed that the descriptors based on frontier electron density and a new DFT based quantum chemical descriptor, nucleus independent chemical shift (NICS) are likely to be responsible for the in vitro inhibiting activity of BPA and MPBA. It has been proposed that NICS accounts for pi...pi interaction and indeed leads to a better result. To the best of our knowledge, this is the first use of NICS as a descriptor to get a better relationship to facilitate the design of COX inhibitors with potentially higher biological activity.

  19. QM Computations on Complete Nucleic Acids Building Blocks: Analysis of the Sarcin-Ricin RNA Motif Using DFT-D3, HF-3c, PM6-D3H, and MM Approaches.

    Science.gov (United States)

    Kruse, Holger; Havrila, Marek; Šponer, Jiřı

    2014-06-10

    A set of conformations obtained from explicit solvent molecular dynamics (MD) simulations of the Sarcin-Ricin internal loop (SRL) RNA motif is investigated using quantum mechanical (QM, TPSS-D3/def2-TZVP DFT-D3) and molecular mechanics (MM, AMBER parm99bsc0+χol3 force field) methods. Solvent effects are approximated using implicit solvent methods (COSMO for DFT-D3; GB and PB for MM). Large-scale DFT-D3 optimizations of the full 11-nucleotide motif are compared to MM results and reveal a higher flexibility of DFT-D3 over the MM in the optimization procedure. Conformational energies of the SRL motif expose significant differences in the DFT-D3 and MM energy descriptions that explain difficulties in MD simulations of the SRL motif. The TPSS-D3 data are in excellent agreement with results obtained by the hybrid functionals PW6B95-D3 and M06-2X. Computationally more efficient methods such as PM6-D3H and HF-3c show promising but partly inconsistent results. It is demonstrated that large-scale DFT-D3 computations on complete nucleic acids building blocks are a viable tool to complement the picture obtained from MD simulations and can be used as benchmarks for faster computational methods. Methodological challenges of large-scale QM computations on nucleic acids such as missing solvent-solute interactions and the truncation of the studied systems are discussed.

  20. DFT theoretical investigations of π-conjugated molecules based on thienopyrazine and different acceptor moieties for organic photovoltaic cells

    Directory of Open Access Journals (Sweden)

    Mohammed Bourass

    2016-09-01

    Full Text Available In this work, theoretical study by using the DFT method on eleven conjugated compounds based on thienopyrazine is reported. Different electron side groups were introduced to investigate their effects on the electronic structure; The HOMO, LUMO and Gap energy of these compounds have been calculated and reported in this paper. A systematic theoretical study of such compound has not been reported as we know. Thus, our aim is first, to explore their electronic and spectroscopic properties on the basis of the DFT quantum chemical calculations. Second, we are interested to elucidate the parameters that influence the photovoltaic efficiency toward better understanding of the structure–property relationships. The study of structural, electronic and optical properties for these compounds could help to design more efficient functional photovoltaic organic materials.

  1. Vibrational spectroscopy (FT-IR and FT-Raman) investigation, and hybrid computational (HF and DFT) analysis on the structure of 2,3-naphthalenediol.

    Science.gov (United States)

    Shoba, D; Periandy, S; Karabacak, M; Ramalingam, S

    2011-12-01

    The FT-IR and FT-Raman vibrational spectra of 2,3-naphthalenediol (C(10)H(8)O(2)) have been recorded using Bruker IFS 66V spectrometer in the range of 4000-100 cm(-1) in solid phase. A detailed vibrational spectral analysis has been carried out and the assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The optimized molecular geometry and vibrational frequencies in the ground state are calculated by using the ab initio Hartree-Fock (HF) and DFT (LSDA and B3LYP) methods with 6-31+G(d,p) and 6-311+G(d,p) basis sets. There are three conformers, C1, C2 and C3 for this molecule. The computational results diagnose the most stable conformer of title molecule as the C1 form. The isotropic computational analysis showed good agreement with the experimental observations. Comparison of the fundamental vibrational frequencies with calculated results by HF and DFT methods. Comparison of the simulated spectra provides important information about the capability of computational method to describe the vibrational modes. A study on the electronic properties, such as absorption wavelengths, excitation energy, dipole moment and Frontier molecular orbital energies, are performed by time dependent DFT approach. The electronic structure and the assignment of the absorption bands in the electronic spectra of steady compounds are discussed. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. On the basis of the thermodynamic properties of the title compound at different temperatures have been calculated. The statistical thermodynamic properties (standard heat capacities, standard entropies, and standard enthalpy changes) and their correlations with temperature have been obtained from the theoretical vibrations.

  2. 用一个2维DFT计算实矩阵的二维DFT和另一个实矩阵的2维DFT的IDFT的新公式及其应用%SOME NEW EXPLICIT FORMULAS FOR COMPUTING 2-D DFT OF A REAL MATRIX AND IDFT OF 2-D DFT OF ANOTHER REAL MATRIX BY A SINGLE 2-D DFT AND THEIR APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    孙琦; 唐远炎

    2000-01-01

    熟知,两个N维实向量的DFT,可以用一个N维复向量的DFT计算.最近,S.Moshe和D.Hertz提出一个方法:用一个N维复向量的DFT计算一个N维实向量的DFT和另一个N维实向量的DFT的IDFT.这是一个优美的结果,具有理论意义和应用价值.如何把上面的结果推广到二维的情形,是一个值得研究的问题.一个矩阵的2-D(2维)DFT通常用行列法化为1-D DFT来计算.但是,用行列法把上述一维的结果推广到二维是困难的.作者得到了计算二维情形的一些新的直接公式,其证明是简明的,它们分别推广了已有的结果.同时还指出,在数字信号处理中当处理实信号时,这些公式非常有用.特别地,作者改进了小波分析中的Mallat分解算法%It is well known that the DFT' s of two N-point real vectors can be compute by a single DFT. Resently;S. Moshe and D. Hertz presented a method to compute the DFT of an Npoint real vector and IDFT of the DFT of another N-point real vector by a single DFT. This result is elegant and effective. How to develop above results to case of two dimensional DFT(2-D DFT). It is an interesting problem. The 2-D DFT of a Matrix is usually separably computed(all rows and then all columns) by using 1-D DFT. But it is difficult for generalization of 1-D case, by using usual separable way. The authors obtain some new explicit formulas to compute 2-D case and their proof is straightforward and brief. It is an expansion of 1-D case. The authors also show that these formulas is very useful in digital signal processing when the digital signal is real. In particular, the 2-D Mallat decomposition algorithm is significantly improved.

  3. Trust Based Pervasive Computing

    Institute of Scientific and Technical Information of China (English)

    LI Shiqun; Shane Balfe; ZHOU Jianying; CHEN Kefei

    2006-01-01

    Pervasive computing environment is a distributed and mobile space. Trust relationship must be established and ensured between devices and the systems in the pervasive computing environment. The trusted computing (TC) technology introduced by trusted computing group is a distributed-system-wide approach to the provisions of integrity protection of resources. The TC' notion of trust and security can be described as conformed system behaviors of a platform environment such that the conformation can be attested to a remote challenger. In this paper the trust requirements in a pervasive/ubiquitous environment are analyzed. Then security schemes for the pervasive computing are proposed using primitives offered by TC technology.

  4. PBE–DFT theoretical study of organic photovoltaic materials based on thiophene with 1D and 2D periodic boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Saïl, K., E-mail: sailkari7@yahoo.com; Bassou, G. [Université Djillali Liabès, Laboratoire de Microscopie, Microanalyse de la Matière et Spectroscopie Moléculaire (L2MSM), Faculté des Sciences Exactes (Algeria); Gafour, M. H. [Centre Universitaire Ahmed Zabana de Rélizane, Institut des Sciences Exactes et Sciences de la Nature et de la Vie, Département de Chimie (Algeria); Miloua, F. [Université Djillali Liabès, Laboratoire de Microscopie, Microanalyse de la Matière et Spectroscopie Moléculaire (L2MSM), Faculté des Sciences Exactes (Algeria)

    2015-12-15

    Conjugated organic systems such as thiophene are interesting topics in the field of organic solar cells. We theoretically investigate π-conjugated polymers constituted by n units (n = 1–11) based on the thiophene (Tn) molecule. The computations of the geometries and electronic structures of these compounds are performed using the density functional theory (DFT) at the 6–31 G(d, p) level of theory and the Perdew–Burke–Eenzerhof (PBE) formulation of the generalized gradient approximation with periodic boundary conditions (PBCs) in one (1D) and two (2D) dimensions. Moreover, the electronic properties (HOCO, LUCO, E{sub gap}, V{sub oc}, and V{sub bi}) are determined from 1D and 2D PBC to understand the effect of the number of rings in polythiophene. The absorption properties—excitation energies (E{sub ex}), the maximal absorption wavelength (λ{sub max}), oscillator strengths, and light harvesting—efficiency are studied using the time-dependent DFT method. Our studies show that changing the number of thiophene units can effectively modulate the electronic and optical properties. On the other hand, our work demonstrates the efficiency of theoretical calculation in the PBCs.

  5. Structural characterization, surface characteristics and non covalent interactions of a heterocyclic Schiff base: Evaluation of antioxidant potential by UV-visible spectroscopy and DFT

    Science.gov (United States)

    Chithiraikumar, S.; Gandhimathi, S.; Neelakantan, M. A.

    2017-06-01

    A heterocyclic Schiff base, (E)-4-(1-((pyridin-2-ylmethyl)imino)ethyl)benzene-1,3-diol (L) was synthesized and isolated as single crystals. Its structure was characterized by FT-IR, UV, 1H and 13C NMR, and further confirmed by X-ray crystallography. Qualitatively and quantitatively the various interactions in the crystal structure of L has been analyzed by Hirshfeld surfaces and 2D fingerprint plots. Non covalent interactions have been studied by electron localization function (ELF) and mapped with reduced density gradient (RDG) analysis. The molecular structure was studied computationally by DFT-B3LYP/6-311G(d,p) calculations. HOMO-LUMO energy levels, chemical reactivity descriptors and thermodynamic parameters have been investigated at the same level of theory. The antioxidant potential of L was evaluated experimentally by measuring DPPH free radical scavenging effect using UV-visible spectroscopy and theoretically by DFT. Theoretical parameters, such as bond dissociation enthalpy (BDE) and spin density calculated suggests that antioxidant potential of L is due to H atom abstraction from the sbnd OH group.

  6. Study of Nuclear Quadrupole Resonance on CO-Doped Single-Walled Carbon Nanotubes: A DFT Computation

    Directory of Open Access Journals (Sweden)

    A. Ghasemi

    2012-08-01

    Full Text Available Carbon Monoxide (CO gas adsorption on external surface of zig-zag (5, 0 and armchair (4, 4 semiconducting Single-Walled Carbon Nanotube (SWCNTs were studied using Density Functional Theory (DFT calculations. Geometry optimizations were carried out by B3LYP/ DFT method at 6-311G* level of theory using the Gaussian98. SWCNTs have been proposed as ideal candidates for various applications of gas sensors due to their amazing physical adsorption properties. We studied the Nuclear Quadrupole Resonance (NQR of the zigzag (5, 0 and armchair (4, 4 SWCNTs with the optimal length of 7.13 and 9.8 Å, respectively. For the first time, DFT calculations were performed to calculate the interaction of 13-Carbon quadrupole moment with EFG in the considered model of CO-SWCNTs. The evaluated NQR parameters reveal that the EFG tensors of 13-Carbon are influenced and show particular trends from gas molecules in the SWCNTs due to contribution of C-O gas molecule of SWCNTs.

  7. Synthesis, Characterization and DFT-Based Investigation of a Novel Trinuclear Singly-Chloro-Bridged Copper(II)-1-Vinylimidazole Complex.

    Science.gov (United States)

    Yolcu, Zuhal; Demir, Serkan; Andaç, Ömer; Büyükgüngör, Orhan

    2016-01-01

    A novel trinuclear copper(II) complex [Cu3(μ-Cl)2Cl4(1-Vim)6] with monodentate 1-vinylimidazole (1-Vim) and chloro ligands has been prepared and experimentally characterized by elemental analysis, thermogravimetry (TGA, DTG, DTA), X-ray single crystal diffractometry, TOF-MS and FT-IR spectroscopies. The electronic and structural properties of the complex were further investigated by DFT/TD-DFT methods. Density functional hybrid method (B3LYP) was applied throughout the calculations. The calculated UV-Vis results based on TD-DFT approach were simulated and compared with experimental spectrum. Based on the data obtained, DFT calculations have been found in reasonable accordance with experimental data.

  8. Density Functional Theory (DFT) modeling and Monte Carlo simulation assessment of inhibition performance of some carbohydrazide Schiff bases for steel corrosion

    Science.gov (United States)

    Obot, I. B.; Kaya, Savaş; Kaya, Cemal; Tüzün, Burak

    2016-06-01

    DFT and Monte Carlo simulation were performed on three Schiff bases namely, 4-(4-bromophenyl)-N‧-(4-methoxybenzylidene)thiazole-2-carbohydrazide (BMTC), 4-(4-bromophenyl)-N‧-(2,4-dimethoxybenzylidene)thiazole-2-carbohydrazide (BDTC), 4-(4-bromophenyl)-N‧-(4-hydroxybenzylidene)thiazole-2-carbohydrazide (BHTC) recently studied as corrosion inhibitor for steel in acid medium. Electronic parameters relevant to their inhibition activity such as EHOMO, ELUMO, Energy gap (ΔE), hardness (η), softness (σ), the absolute electronegativity (χ), proton affinity (PA) and nucleophilicity (ω) etc., were computed and discussed. Monte Carlo simulations were applied to search for the most stable configuration and adsorption energies for the interaction of the inhibitors with Fe (110) surface. The theoretical data obtained are in most cases in agreement with experimental results.

  9. Molecular structure, vibrational spectral assignments (FT-IR and FT-RAMAN), NMR, NBO, HOMO-LUMO and NLO properties of O-methoxybenzaldehyde based on DFT calculations

    Science.gov (United States)

    Vennila, P.; Govindaraju, M.; Venkatesh, G.; Kamal, C.

    2016-05-01

    Fourier transform - Infra red (FT-IR) and Fourier transform - Raman (FT-Raman) spectroscopic techniques have been carried out to analyze O-methoxy benzaldehyde (OMB) molecule. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT). The vibrational analysis of stable isomer of OMB has been carried out by FT-IR and FT-Raman in combination with theoretical method simultaneously. The first-order hyperpolarizability and the anisotropy polarizability invariant were computed by DFT method. The atomic charges, hardness, softness, ionization potential, electronegativity, HOMO-LUMO energies, and electrophilicity index have been calculated. The 13C and 1H Nuclear magnetic resonance (NMR) have also been obtained by GIAO method. Molecular electronic potential (MEP) has been calculated by the DFT calculation method. Electronic excitation energies, oscillator strength and excited states characteristics were computed by the closed-shell singlet calculation method.

  10. A DFT Scheme for Pneumatic Control Logic in Flow-based Biochips

    DEFF Research Database (Denmark)

    Potluri, Seetal; Pop, Paul; Madsen, Jan

    2016-01-01

    them to laboratory environments. To address this issue, recent work has focused on reducing the number of off-chip pressure sources, using on-chip pneumatic control logic circuits fabricated using three-layer monolithic membrane valve technology. Since these on-chip pneumatic control logic circuits...... in turn control the fluidic operations, it is very important that they are fault-free, in order to avoid the failure of biochemical applications. For the first time, this paper proposes a design-for-testability (DFT) scheme to test for faults inside on-chip pneumatic control logic circuits, by adding...... observation pneumatic latches into the circuit. We show that the problem of attaining high fault coverage by adding minimum number of observation pneumatic latches, is an instance of the set cover problem, which is NP-hard. We use a greedy set cover algorithm and show that our DFT scheme attains a fault...

  11. The interaction of beryllium with benzene and graphene: a comparative investigation based on DFT, MP2, CCSD(T), CAS-SCF and CAS-PT2.

    Science.gov (United States)

    Fernandez, Nicolas; Ferro, Yves; Carissan, Yannick; Marchois, Julien; Allouche, Alain

    2014-02-07

    The interaction of beryllium with benzene, graphene and graphitic compounds involves multi-reference electronic states, Jahn-Teller distortion, charge transfer and van der Waals interactions. This is investigated herein using periodic and molecular models at different levels of theory: (i) the second-order Møller-Plesset (MP2) perturbation theory, (ii) the coupled cluster method with inclusion of single double and perturbative triple excitations (CCSD(T)), (iii) the complete active space self-consistent field (CAS-SCF) and (iv) the complete active space with perturbation theory truncated at the 2nd order (CAS-PT2). Molecular and periodic Density Functional Theory (DFT) methods are also used. The two major failures of DFT are addressed with regard to the beryllium benzene and graphene interaction: the degeneracy problem is the source of no specific problem while the delocalization error causes DFT with the Perdew Burke, Ernzerhof functional plus the Grimme correction (DFT/PBE-D2) to be over-binding by about 0.4 eV at a short-range. The agreement between DFT/PBE-D2 and wave-function based methods is nevertheless good; DFT/PBE-D2 provides an accurate description of the electronic structure of the system. By the end of this work, we shall get a better insight into the mechanisms leading beryllium to physisorb on graphene and to chemisorb into the bilayer of graphite.

  12. Patient-specific dosimetry based on quantitative SPECT imaging and 3D-DFT convolution

    Energy Technology Data Exchange (ETDEWEB)

    Akabani, G.; Hawkins, W.G.; Eckblade, M.B.; Leichner, P.K. [Univ. of Nebraska Medical Center, Omaha, NE (United States)

    1999-01-01

    The objective of this study was to validate the use of a 3-D discrete Fourier Transform (3D-DFT) convolution method to carry out the dosimetry for I-131 for soft tissues in radioimmunotherapy procedures. To validate this convolution method, mathematical and physical phantoms were used as a basis of comparison with Monte Carlo transport (MCT) calculations which were carried out using the EGS4 system code. The mathematical phantom consisted of a sphere containing uniform and nonuniform activity distributions. The physical phantom consisted of a cylinder containing uniform and nonuniform activity distributions. Quantitative SPECT reconstruction was carried out using the Circular Harmonic Transform (CHT) algorithm.

  13. Role of the lattice dynamics in La2-xBaxCuO4 superconductor based on DFT method

    Directory of Open Access Journals (Sweden)

    A Tavana

    2010-09-01

    Full Text Available Electron-phonon coupling parameters are calculated for La2-x BaxCuO4 cuprate superconductor in a wide range of dopings, from undoped to overdoped compounds. In this study we aim to study the quality of such calculations based on DFT method so, the results of σ GGA+U electronic structure calculations are also investigated. The obtained value for electron-phonon coupling is in the same order of previous calculations but, the value obtained for the Hubbard U parameter shows that, such methods are poor in the estimation of electronic correlations to decide about the role of phonons in these compounds based on their results. Moreover, existence of several structural phase transitions with temperature and doping, lead to larger error in these calculations. Based on the calculated phonon dispersions, structural phase transitions can be resulted which shows the ability of DFT in the study of structural properties and the weakness of the strongly correlations in this properties.

  14. Agent Based Computing Machine

    Science.gov (United States)

    2005-12-09

    be used in Phase 2 to accomplish the following enhancements. Due to the speed and support of MPI for C/C++ on Beowulf clusters , these languages could...1.7 ABC Machine Formal Definition 24 1.8 Computational Analysis 31 1.9 Programming Concepts 34 1.10 Cluster Mapping 38 1.11 Phase 1 Results 43 2...options for hardware implementation are explored including an emulation with a high performance cluster , a high performance silicon chip and the

  15. Liquid-liquid extraction of metal ions, DFT and TD-DFT analysis of some 1,2,4-triazole Schiff Bases with high selectivity for Pb(II) and Fe(II)

    Science.gov (United States)

    Khoutoul, Mohamed; Lamsayah, Morad; Al-blewi, Fawzia F.; Rezki, Nadjet; Aouad, Mohamed Reda; Mouslim, Messali; Touzani, Rachid

    2016-06-01

    Liquid-liquid extraction of metal ions using some 1,2,4-triazole Schiff base derivatives as new extractants was studied. Fe2+, Zn2+, Cu2+, Co2+, Cd2+ and Pb2+ were extracted from the aqueous phase into the organic phase and the extractability for each metal ion was determined by atomic absorption. Interestingly, a competitive extraction was also investigated and then examined at different pH in order to explore the effect of the different substituent groups on metal extraction. Accordingly, high selectivity towards Fe2+ (90.1%) and Pb2+ (94.3%) provided respectively by the presence of electron withdrawing group and electron donor group was attained. In addition, geometry optimizations of the ground and excited-states of the ligands in order to get better insight into the geometry and the electronic structure were carried out by means of DFT and TD-DFT calculations.

  16. Capability-based computer systems

    CERN Document Server

    Levy, Henry M

    2014-01-01

    Capability-Based Computer Systems focuses on computer programs and their capabilities. The text first elaborates capability- and object-based system concepts, including capability-based systems, object-based approach, and summary. The book then describes early descriptor architectures and explains the Burroughs B5000, Rice University Computer, and Basic Language Machine. The text also focuses on early capability architectures. Dennis and Van Horn's Supervisor; CAL-TSS System; MIT PDP-1 Timesharing System; and Chicago Magic Number Machine are discussed. The book then describes Plessey System 25

  17. Vibrational and structural study of onopordopicrin based on the FTIR spectrum and DFT calculations.

    Science.gov (United States)

    Chain, Fernando E; Romano, Elida; Leyton, Patricio; Paipa, Carolina; Catalán, César A N; Fortuna, Mario; Brandán, Silvia Antonia

    2015-01-01

    In the present work, the structural and vibrational properties of the sesquiterpene lactone onopordopicrin (OP) were studied by using infrared spectroscopy and density functional theory (DFT) calculations together with the 6-31G(∗) basis set. The harmonic vibrational wavenumbers for the optimized geometry were calculated at the same level of theory. The complete assignment of the observed bands in the infrared spectrum was performed by combining the DFT calculations with Pulay's scaled quantum mechanical force field (SQMFF) methodology. The comparison between the theoretical and experimental infrared spectrum demonstrated good agreement. Then, the results were used to predict the Raman spectrum. Additionally, the structural properties of OP, such as atomic charges, bond orders, molecular electrostatic potentials, characteristics of electronic delocalization and topological properties of the electronic charge density were evaluated by natural bond orbital (NBO), atoms in molecules (AIM) and frontier orbitals studies. The calculated energy band gap and the chemical potential (μ), electronegativity (χ), global hardness (η), global softness (S) and global electrophilicity index (ω) descriptors predicted for OP low reactivity, higher stability and lower electrophilicity index as compared with the sesquiterpene lactone cnicin containing similar rings.

  18. A new vibrational study of Acetazolamide compound based on normal coordinate analysis and DFT calculations

    Science.gov (United States)

    Brandán, S. A.; Eroğlu, E.; Ledesma, A. E.; Oltulu, O.; Yalçınkaya, O. B.

    2011-05-01

    We have studied the 5-acetamido-1,3,4-thiadiazole-2-sulphonamide compound and characterized it by infrared and Raman spectroscopy in the solid phase. The Density Functional Theory (DFT) method together with Pople's basis set show that two stable molecules for the compound have been theoretically determined in the gas phase, and that only the more stable conformation is present in the solid phase, as was experimentally observed. The harmonic vibrational wavenumbers for the optimized geometry were calculated at B3LYP/6-31G ∗ and B3LYP/6-311++G ∗∗ levels at the proximity of the isolated molecule. For a complete assignment of the vibrational spectra in the compound solid, DFT calculations were combined with Pulaýs Scaled Quantum Mechanics Force Field (SQMFF) methodology in order to fit the theoretical wavenumber values to the experimental ones. In this way, a complete assignment of all of the observed bands in the infrared spectrum for the compound was performed. The natural bond orbital (NBO) study reveals the characteristics of the electronic delocalization of the two structures, while the corresponding topological properties of electronic charge density are analysed by employing Bader's Atoms in the Molecules theory (AIM).

  19. DFT/TD-DFT characterization of conjugational electronic structures and spectral properties of materials based on thieno[3,2-b][1]benzothiophene for organic photovoltaic and solar cell applications

    Directory of Open Access Journals (Sweden)

    Mohamed Bourass

    2017-07-01

    Full Text Available In this work, a theoretical study on five organic π-conjugated molecules based on thieno[3,2-b][1]benzothiophene using together quantum methods, density functional theory (DFT and its derivative time dependent-density functional theory (TD-DFT is reported. Different electron side groups were introduced as a bridge to investigate their effects on the electronic structure; The HOMO, LUMO, chemical hardness (η, chemical potential (μ, electronegativity (χ, electrophilicity power (ω, reorganization energy total (λtotal, open circuit voltage (Voc, the gap energy and NBO analysis of these compounds have been reported and discussed in this paper. Thus, our aim is to explore their electronic and spectroscopic properties on the basis of the DFT quantum chemical calculations, and at the same time, we are interested to make an idea on the parameters influencing the photovoltaic efficiency toward a better understanding of the structure–property relationships. The calculated results of these compounds reveal that C4, C5, with thiophene and thienopyrazine as a bridge group respectively, can be used as a potential donor of electron in organic Bulk Heterojunction solar cells (BHJ, due to its best electronic and optical properties and good photovoltaic parameters. The study of electronic, optical and structural properties of these compounds could help to design more efficient functional photovoltaic organic materials.

  20. A ligand field series for the 4f-block from experimental and DFT computed Ce(IV/III) electrochemical potentials.

    Science.gov (United States)

    Bogart, Justin A; Lewis, Andrew J; Boreen, Michael A; Lee, Heui Beom; Medling, Scott A; Carroll, Patrick J; Booth, Corwin H; Schelter, Eric J

    2015-03-16

    Understanding of the sensitivity of the reduction potential of cerium(IV) cations to ligand field strength has yet to benefit from systematic variation of the ligand environment. Detailed analyses for a series of seven cerium(IV) tetrakis(pyridyl-nitroxide) compounds and their cerium(III) analogues in varying ligand field strengths are presented. Electrochemical, spectroscopic, and computational results reveal a close correlation of electronic properties with ligand substituents. Together with electrochemical data for reported eight-coordinate compounds, DFT calculations reveal a broad range of the cerium(IV/III) redox potentials correlated to ligand field strengths, establishing a semiempirical, predictive model for the modulation of cerium redox thermodynamics and ligand field strengths. Applications over a variety of scientific disciplines make use of the fundamental redox thermodynamics of cerium. Such applications will benefit from a combined experimental and theoretical approach for assessing redox cycling of cerium compounds.

  1. Structural studies on Mannich bases of 2-Hydroxy-3,4,5,6-tetrachlorobenzene. An UV, IR, NMR and DFT study. A mini-review

    DEFF Research Database (Denmark)

    Hansen, Poul Erik; Spanget-Larsen, Jens

    2016-01-01

    Mannich bases of 2-Hydroxy-3,4,5,6-tetrachlorobenzene are chosen as an exemplary case for tautomeric Mannich bases. Molecular structures are calculated. OH stretching frequencies are rationalized based on DFT calculations. Intrinsic deuterium isotope effects on 13C chemical shifts in the M-form a...

  2. Function-Space-Based Solution Scheme for the Size-Modified Poisson-Boltzmann Equation in Full-Potential DFT.

    Science.gov (United States)

    Ringe, Stefan; Oberhofer, Harald; Hille, Christoph; Matera, Sebastian; Reuter, Karsten

    2016-08-01

    The size-modified Poisson-Boltzmann (MPB) equation is an efficient implicit solvation model which also captures electrolytic solvent effects. It combines an account of the dielectric solvent response with a mean-field description of solvated finite-sized ions. We present a general solution scheme for the MPB equation based on a fast function-space-oriented Newton method and a Green's function preconditioned iterative linear solver. In contrast to popular multigrid solvers, this approach allows us to fully exploit specialized integration grids and optimized integration schemes. We describe a corresponding numerically efficient implementation for the full-potential density-functional theory (DFT) code FHI-aims. We show that together with an additional Stern layer correction the DFT+MPB approach can describe the mean activity coefficient of a KCl aqueous solution over a wide range of concentrations. The high sensitivity of the calculated activity coefficient on the employed ionic parameters thereby suggests to use extensively tabulated experimental activity coefficients of salt solutions for a systematic parametrization protocol.

  3. QSPR Studies on lgKow and lgKoc of Fluorobenzenes and Property Parameters Based on HF and DFT Calculations

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xing-Chuan; YU Jing; WANG Zun-Yao; LIU Hong-Xia

    2006-01-01

    Quantum chemistry parameters of 22 fluorobenzenes were computed at six levels using Hartree-Fock and DFT methods. Based on the experimental data of n-octanol/water partition coefficient (lgKow), a three-parameter (dipole moments (μ), zero point energy (ZPE) and free energy (G°)) quantitative correlation equation that can predict lgKow was developed using structural and thermodynamic parameters as theoretical descriptors. Similarly, based on experimental data of soil organic carbon sorption coefficient (lgKoc), the other three-parameter (the most negative atomic net charge of molecule (q-), dipole moments (μ) and molecular volume (Vi)) quantitative correlation equation that can predict lgKoc was given. Quantitative correlation equations based on B3LYP/6-311G** calculation were validated by VIF (variance inflation factors) and t-test and used to predict lgKow and lgKoc of a series of compounds. The result showed that the correlation and prediction ability of lgKoc equations based on three levels of HF/STO-3G, B3LYP/6-31G* and B3LYP/6-311G** are all more advantageous than those based on AM1.

  4. Density Functional Theory (DFT Study of Coumarin-based Dyes Adsorbed on TiO2 Nanoclusters—Applications to Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Mihai A. Gîrţu

    2013-06-01

    Full Text Available Coumarin-based dyes have been successfully used in dye-sensitized solar cells, leading to photovoltaic conversion efficiencies of up to about 8%. Given the need to better understand the behavior of the dye adsorbed on the TiO2 nanoparticle, we report results of density functional theory (DFT and time-dependent DFT (TD-DFT studies of several coumarin-based dyes, as well as complex systems consisting of the dye bound to a TiO2 cluster. We provide the electronic structure and simulated UV-Vis spectra of the dyes alone and adsorbed to the cluster and discuss the matching with the solar spectrum. We display the energy level diagrams and the electron density of the key molecular orbitals and analyze the electron transfer from the dye to the oxide. Finally, we compare our theoretical results with the experimental data available and discuss the key issues that influence the device performance.

  5. Application of artificial neural networks and DFT-based parameters for prediction of reaction kinetics of ethylbenzene dehydrogenase

    Science.gov (United States)

    Szaleniec, Maciej; Witko, Małgorzata; Tadeusiewicz, Ryszard; Goclon, Jakub

    2006-03-01

    Artificial neural networks (ANNs) are used for classification and prediction of enzymatic activity of ethylbenzene dehydrogenase from EbN1 Azoarcus sp. bacterium. Ethylbenzene dehydrogenase (EBDH) catalyzes stereo-specific oxidation of ethylbenzene and its derivates to alcohols, which find its application as building blocks in pharmaceutical industry. ANN systems are trained based on theoretical variables derived from Density Functional Theory (DFT) modeling, topological descriptors, and kinetic parameters measured with developed spectrophotometric assay. Obtained models exhibit high degree of accuracy (100% of correct classifications, correlation between predicted and experimental values of reaction rates on the 0.97 level). The applicability of ANNs is demonstrated as useful tool for the prediction of biochemical enzyme activity of new substrates basing only on quantum chemical calculations and simple structural characteristics. Multi Linear Regression and Molecular Field Analysis (MFA) are used in order to compare robustness of ANN and both classical and 3D-quantitative structure-activity relationship (QSAR) approaches.

  6. Paper-Based and Computer-Based Concept Mappings: The Effects on Computer Achievement, Computer Anxiety and Computer Attitude

    Science.gov (United States)

    Erdogan, Yavuz

    2009-01-01

    The purpose of this paper is to compare the effects of paper-based and computer-based concept mappings on computer hardware achievement, computer anxiety and computer attitude of the eight grade secondary school students. The students were randomly allocated to three groups and were given instruction on computer hardware. The teaching methods used…

  7. Agent-Based Cloud Computing

    OpenAIRE

    Sim, Kwang Mong

    2012-01-01

    Agent-based cloud computing is concerned with the design and development of software agents for bolstering cloud service\\ud discovery, service negotiation, and service composition. The significance of this work is introducing an agent-based paradigm for\\ud constructing software tools and testbeds for cloud resource management. The novel contributions of this work include: 1) developing\\ud Cloudle: an agent-based search engine for cloud service discovery, 2) showing that agent-based negotiatio...

  8. Interpretation of the photoelectron, ultraviolet, and vacuum ultraviolet photoabsorption spectra of bromobenzene by ab initio configuration interaction and DFT computations

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Michael H., E-mail: m.h.palmer@ed.ac.uk; Ridley, Trevor, E-mail: t.ridley@ed.ac.uk, E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: malgorzata.biczysko@sns.it, E-mail: kipeters@wsu.edu [School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, Scotland (United Kingdom); Hoffmann, Søren Vrønning, E-mail: t.ridley@ed.ac.uk, E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: malgorzata.biczysko@sns.it, E-mail: kipeters@wsu.edu; Jones, Nykola C., E-mail: t.ridley@ed.ac.uk, E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: malgorzata.biczysko@sns.it, E-mail: kipeters@wsu.edu [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Coreno, Marcello, E-mail: t.ridley@ed.ac.uk, E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: malgorzata.biczysko@sns.it, E-mail: kipeters@wsu.edu [CNR-IMIP, Montelibretti, c/o Laboratorio Elettra, Trieste (Italy); Simone, Monica de, E-mail: t.ridley@ed.ac.uk, E-mail: vronning@phys.au.dk, E-mail: nykj@phys.au.dk, E-mail: marcello.coreno@elettra.eu, E-mail: desimone@iom.cnr.it, E-mail: malgorzata.biczysko@sns.it, E-mail: kipeters@wsu.edu [CNR-IOM Laboratorio TASC, Trieste (Italy); Grazioli, Cesare [CNR-IOM Laboratorio TASC, Trieste (Italy); Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste (Italy); Zhang, Teng [Department of Physics and Astronomy, University of Uppsala, Uppsala (Sweden); and others

    2015-10-28

    New photoelectron, ultraviolet (UV), and vacuum UV (VUV) spectra have been obtained for bromobenzene by synchrotron study with higher sensitivity and resolution than previous work. This, together with use of ab initio calculations with both configuration interaction and time dependent density functional theoretical methods, has led to major advances in interpretation. The VUV spectrum has led to identification of a considerable number of Rydberg states for the first time. The Franck-Condon (FC) analyses including both hot and cold bands lead to identification of the vibrational structure of both ionic and electronically excited states including two Rydberg states. The UV onset has been interpreted in some detail, and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. In a similar way, the 6 eV absorption band which is poorly resolved is analysed in terms of the presence of two ππ* states of {sup 1}A{sub 1} (higher oscillator strength) and {sup 1}B{sub 2} (lower oscillator strength) symmetries, respectively. The detailed analysis of the vibrational structure of the 2{sup 2}B{sub 1} ionic state is particularly challenging, and the best interpretation is based on equation-of-motion-coupled cluster with singles and doubles computations. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene. The equilibrium structures of the 3b{sub 1}3s and 6b{sub 2}3s (valence shell numbering) Rydberg states have been obtained and compared with the corresponding ionic limit structures.

  9. Hypercomputation based on quantum computing

    CERN Document Server

    Sicard, A; Ospina, J; Sicard, Andr\\'es; V\\'elez, Mario; Ospina, Juan

    2004-01-01

    We present a quantum algorithm for a (classically) incomputable decision problem: the Hilbert's tenth problem; namely, we present a hypercomputation model based on quantum computation. The model is inspired by the one proposed by Tien D. Kieu. Our model exploits the quantum adiabatic process and the characteristics of the representation of the dynamical algebra su(1,1) associated to the infinite square well. Furthermore, it is demonstrated that the model proposed is a universal quantum computation model.

  10. A DFT based equilibrium study of a chemical mixture Tachyhydrite and their lower hydrates for long term heat storage

    Science.gov (United States)

    Pathak, A. D.; Nedea, S. V.; Zondag, H. A.; Rindt, C. C. M.; Smeulders, D. M. J.

    2016-09-01

    Chloride based salt hydrates are promising materials for seasonal heat storage. However, hydrolysis, a side reaction, deteriorates, their cycle stability. To improve the kinetics and durability, we have investigated the optimum operating conditions of a chemical mixture of CaCl2 and MgCl2 hydrates. In this study, we apply a GGA-DFT to gain insight into the various hydrates of CaMg2Cl6. We have obtained the structural properties, atomic charges and vibrational frequencies of CaMg2Cl6 hydrates. The entropic contribution and the enthalpy change are quantified from ground state energy and harmonic frequencies. Subsequently, the change in the Gibbs free energy of thermolysis was obtained under a wide range of temperature and pressure. The equilibrium product concentration of thermolysis can be used to design the seasonal heat storage system under different operating conditions.

  11. A Robust Non-Blind Watermarking Technique for Color Video Based on Combined DWT-DFT Transforms and SVD Technique

    Directory of Open Access Journals (Sweden)

    Nandeesh B

    2014-08-01

    Full Text Available The rise of popularity of Digital video in the past decade has been tremendous thereby leading to malicious copying and distribution. So the need for preservation of ownership and in tackling copyright issues has become an imminent issue. Digital Video Watermarking has been in existence as a solution for this. The paper proposes a non-blind watermarking technique based on combined DWT-DFT transforms using singular values of SVD matrix in YCbCr color space. The technique uses Fibonacci series for selection of frames to enhance security and thereby maintaining quality of original video. Watermark encryption is done by scrambling the watermark using Arnold transform. Geometric and non-geometric attacks on watermarked video have been performed to test the robustness of the proposed technique. Quality of watermarked video is measured using PSNR and NC gives the similarity between extracted and the original watermark.

  12. Structural, spectroscopic and DFT study of 4-methoxybenzohydrazide Schiff bases. A new series of polyfunctional ligands

    Science.gov (United States)

    Ferraresi-Curotto, Verónica; Echeverría, Gustavo A.; Piro, Oscar E.; Pis-Diez, Reinaldo; González-Baró, Ana C.

    2015-02-01

    Five Schiff bases obtained from condensation of 4-methoxybenzohydrazide with related aldehydes, namely o-vanillin, vanillin, 5-bromovanillin, 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde were prepared. A detailed structural and spectroscopic study is reported. The crystal structures of four members of the family were determined and compared with one another. The hydrazones obtained from 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde resulted to be isomorphic to each other. The solid-state structures are stabilized by intra-molecular Osbnd H⋯N interactions in salicylaldehyde derivatives between the Osbnd H moiety from the aldehyde and the hydrazone nitrogen atom. All crystals are further stabilized by inter-molecular H-bonds mediated by the crystallization water molecule. A comparative analysis between experimental and theoretical results is presented. The conformational space was searched and geometries were optimized both in gas phase and including solvent effects. The structure is predicted for the compound for which the crystal structure was not determined. Infrared and electronic spectra were measured and assigned with the help of data obtained from computational methods based on the Density Functional Theory.

  13. Structural, spectroscopic and DFT study of 4-methoxybenzohydrazide Schiff bases. A new series of polyfunctional ligands.

    Science.gov (United States)

    Ferraresi-Curotto, Verónica; Echeverría, Gustavo A; Piro, Oscar E; Pis-Diez, Reinaldo; González-Baró, Ana C

    2015-02-25

    Five Schiff bases obtained from condensation of 4-methoxybenzohydrazide with related aldehydes, namely o-vanillin, vanillin, 5-bromovanillin, 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde were prepared. A detailed structural and spectroscopic study is reported. The crystal structures of four members of the family were determined and compared with one another. The hydrazones obtained from 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde resulted to be isomorphic to each other. The solid-state structures are stabilized by intra-molecular O-H⋯N interactions in salicylaldehyde derivatives between the O-H moiety from the aldehyde and the hydrazone nitrogen atom. All crystals are further stabilized by inter-molecular H-bonds mediated by the crystallization water molecule. A comparative analysis between experimental and theoretical results is presented. The conformational space was searched and geometries were optimized both in gas phase and including solvent effects. The structure is predicted for the compound for which the crystal structure was not determined. Infrared and electronic spectra were measured and assigned with the help of data obtained from computational methods based on the Density Functional Theory.

  14. Structural analyses of experimental 13C edited amide I' IR and VCD for peptide β-sheet aggregates and fibrils using DFT-based spectral simulations.

    Science.gov (United States)

    Welch, William R W; Keiderling, Timothy A; Kubelka, Jan

    2013-09-12

    In the preceding paper, computational models based on density functional theory (DFT) were presented to characterize the sensitivity of vibrational spectroscopic methods (IR, VCD, and Raman) to structural features of β-sheets. Isotopically edited amide I' IR for peptides labeled with (13)C in multiple different sites provides the most structurally distinct signatures of strand alignment, while VCD is sensitive to the sheet twist and intersheet stacking. In this report, we simulate the IR and VCD spectra for models approximating structures of four β-sheet forming peptides previously experimentally studied using these methods with (13)C isotopic editing. Various register alignments are tested. Agreement with experiment is evaluated based on frequency shifts of both the (12)C and (13)C IR amide I' signals, relative intensity patterns, and VCD spectra where available. While for the simulation of IR spectra canonical planar sheets provide a sufficient model system, for VCD simulation twisted, stacked sheets are required in order to reproduce strong couplet-like amide I' VCD. Effects of the solvent (water) and amino acid side chains are also tested by using a simplified, electrostatic solvent model and atomic partial charges for the side chains. Very good agreement with experimental spectra is obtained, particularly for the relative (12)C and (13)C band frequencies. All four peptide models are shown to be antiparallel as had previously been assumed. However, in some cases our simulations are consistent with different register alignment of strands than originally proposed.

  15. Assessment of DFT functionals with fluorine-fluorine coupling constants

    Science.gov (United States)

    García de la Vega, J. M.; San Fabián, J.

    2015-07-01

    Density functional theory (DFT) calculations of nuclear magnetic resonance (NMR) spin-spin coupling constants (SSCCs) provide an important contribution for understanding experimentally observed values. It is known that calculated SSCCs using DFT methods correlate well with those experimentally measured. Unlike most of SSCCs, in fluorine compounds, fluorine-fluorine SSCC JFF shows that the Fermi contact (FC) term is not dominant, particularly for JFF in polyfluorinated organic molecules. In order to devise a DFT approach that would correctly reproduce the variation of SSCCs within a series of fluorine compounds, we test several DFT-based approaches, using different exchange and correlation functionals. Isotropic contributions to NMR fluorine-fluorine coupling constants (FC, spin-dipolar, SD, paramagnetic spin-orbit, PSO, and diamagnetic spin-orbit, DSO) have been calculated. Results show that DFT methods give appropriate values for nJFF (n = 4 to 7), while for geminal and vicinal JFF present large deviations from experimental values. For the latter SSCCs (2JFF and 3JFF), the four contributions (FC, SD, PSO and DSO) are analysed as a function of the local and nonlocal exchange in 1,1- and 1,2-difluoroethylene. Although FC term is not dominant for these SSCCs, the variation of this contribution with exchange is remarkable. On the other hand, SD and PSO contributions can be suitably computed without and with exact exchange, respectively. This article is dedicated to the memory of Prof. N. C. Handy, whose contributions to the development of Theoretical Chemistry have been widely recognized.

  16. A New Approach for Studying Bond Rupture/Closure of a Spiro Benzopyran Photochromic Material: Reactivity Descriptors Derived from Frontier Orbitals and DFT Computed Electrostatic Potential Energy Surface Maps

    Directory of Open Access Journals (Sweden)

    M. S. A. Abdel-Mottaleb

    2016-01-01

    Full Text Available This paper focuses on computations technique within the framework of the TD-DFT theory for studying the relationship between structure-properties of reversible conversion of photochromic materials. Specifically, we report on 1′,3′-dihydro-8-methoxy-1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-(2H-indole] (SP and its isomers. TD-DFT calculated UV-Vis electronic spectra of the closed and open isomers of this photochromic material are in excellent agreement with the experimental results. Moreover, this paper reports on the results of theoretical investigations of reactivity indices that may govern the conversion between spiropyrans and its isomers. In addition, the solvent and rigidity of the medium significantly control the thermal bleaching of the photogenerated colored isomers and hence the switch ability pattern of the photochromic material. The effect of molecular structure computed by DFT in gas-phase and solvents on Cspiro-O bond length has been shown to correlate with photochromic properties. For this compound, DFT optimized geometry could be used to predict photochromism. Furthermore, in an attempt to predict the driving force for MC → SP, this work explores, for the first time, profitable exploitation of the calculated and visualized mapped electrostatic potential energy surfaces (ESP map. Interestingly, it seems that the electrostatic potential forces over the molecular fragments govern spirobond rupture/closure reactions. Thermodynamically, all-trans-colored isomer (CTT is the most stable merocyanine-like form.

  17. DFT based study of transition metal nano-clusters for electrochemical NH3 production

    DEFF Research Database (Denmark)

    Howalt, Jakob Geelmuyden; Bligaard, Thomas; Rossmeisl, Jan;

    2013-01-01

    Theoretical studies of the possibility of producing ammonia electrochemically at ambient temperature and pressure without direct N2 dissociation are presented. Density functional theory calculations were used in combination with the computational standard hydrogen electrode to calculate the free ...

  18. Effects of doping of calcium atom(s) on structural, electronic and optical properties of binary strontium chalcogenides - A theoretical investigation using DFT based FP-LAPW methodology

    Science.gov (United States)

    Bhattacharjee, Rahul; Chattopadhyaya, Surya

    2017-09-01

    The effects of doping of Ca atom(s) on structural, electronic and optical properties of binary strontium chalcogenide semiconductor compounds have been investigated theoretically using DFT based FP-LAPW approach by modeling the rock-salt (B1) ternary alloys CaxSr1-xS, CaxSr1-xSe and CaxSr1-xTe at some specific concentrations 0 ≤ x ≤ 1 and studying their aforesaid properties. The exchange-correlation potentials for their structural properties have been computed using the Wu-Cohen generalized-gradient approximation (WC-GGA) scheme, while those for the electronic and optical properties have been computed using recently developed Tran-Blaha modified Becke-Johnson (TB-mBJ) scheme. In addition, we have computed the electronic and optical properties with the traditional BLYP and PBE-GGA schemes for comparison. The atomic and orbital origin of different electronic states in the band structure of each of the compounds have been identified from the respective density of states (DOS). Using the approach of Zunger and co-workers, the microscopic origin of band gap bowing has been discussed in term of volume deformation, charge exchange and structural relaxation. Bonding characteristics among the constituent atoms of each of the specimens have been discussed from their charge density contour plots. Optical properties of the binary compounds and ternary alloys have been investigated theoretically in terms of their respective dielectric function, refractive index, normal incidence reflectivity and optical conductivity. Several calculated results have been compared with available experimental and other theoretical data.

  19. DFT study on the attacking mechanisms of H and OH radicals to G-C and A-T base pairs in water

    Energy Technology Data Exchange (ETDEWEB)

    Okutsu, N.; Shimamura, K.; Shimizu, E.; Kurita, N., E-mail: kurita@cs.tut.ac.jp [Department of Computer Science and Engineering, Toyohashi University of Technology, Toyohashi, Aichi, 441-8580 (Japan); Shulga, S. [Institute for Food Biotechnology and Genomics, National Academy of Sciences of Ukraine, Kyiv (Ukraine); Danilov, V. I. [Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv (Ukraine)

    2016-02-01

    To elucidate the effect of radicals on DNA base pairs, we investigated the attacking mechanism of OH and H radicals to the G-C and A-T base pairs, using the density functional theory (DFT) calculations in water approximated by the continuum solvation model. The DFT calculations revealed that the OH radical abstracts the hydrogen atom of a NH{sub 2} group of G or A base and induces a tautomeric reaction for an A-T base pair more significantly than for a G-C base pair. On the other hand, the H radical prefers to bind to the Cytosine NH{sub 2} group of G-C base pair and induce a tautomeric reaction from G-C to G*-C*, whose activation free energy is considerably small (−0.1 kcal/mol) in comparison with that (42.9 kcal/mol) for the reaction of an A-T base pair. Accordingly, our DFT calculations elucidated that OH and H radicals have a significant effect on A-T and G-C base pairs, respectively. This finding will be useful for predicting the effect of radiation on the genetic information recorded in the base sequences of DNA duplexes.

  20. Synthesis, crystal structure analysis, spectral investigations, DFT computations and molecular dynamics and docking study of 4-benzyl-5-oxomorpholine-3-carbamide, a potential bioactive agent

    Science.gov (United States)

    Murthy, P. Krishna; Sheena Mary, Y.; Shyma Mary, Y.; Panicker, C. Yohannan; Suneetha, V.; Armaković, Stevan; Armaković, Sanja J.; Van Alsenoy, C.; Suchetan, P. A.

    2017-04-01

    4-benzyl-5-oxomorpholine-3-carbamide has been synthesized; single crystals were grown by slow evaporation solution growth technique at room temperature and characterized by single crystal X-ray diffraction, FT-IR, FT-Raman and 1H-NMR. The compound crystallizes in the monoclinic space group P21/n. The molecular geometry of the compound was optimized by using Density Functional Theory (DFT/B3LYP) method with 6-311++G(d,p) basis set in the ground state and geometric parameters are in agreement with the X-ray analysis results of the structure. The experimental vibrational spectra were compared with the calculated spectra and each vibrational wave number was assigned on the basis of potential energy distribution (PED). The electronic and charge transfer properties have been explained on the basis of highest occupied molecular orbital's (HOMOs) and lowest unoccupied molecular orbital's (LUMOs). Besides molecular electrostatic potential (MEP), frontier molecular orbital's (FMOs), some global reactivity descriptors, thermodynamic properties, non-linear optical (NLO) behavior and Mullikan charge analysis of the title compound were computed with the same method in gas phase, theoretically. Potential reactive sites of the title compound have been identified by average local ionization energy and Fukui functions, both mapped to the electron density surface. Bond dissociation energies for all single acyclic bonds have been calculated in order to investigate autoxidation and degradation properties of the title compound. Atoms with pronounced interactions with water molecules have been detected by calculations of radial distribution functions after molecular dynamics simulations. The experimental results are compared with the theoretical calculations using DFT methods for the fortification of the paper. Further the docking studies revealed that the title compound as a docked ligand forms a stable complex with pyrrole inhibitor with a binding affinity value of -7.5 kcal/mol. This

  1. Non-opioid analgesic drug flupirtine: Spectral analysis, DFT computations, in vitro bioactivity and molecular docking study

    Science.gov (United States)

    Leenaraj, D. R.; Hubert Joe, I.

    2017-06-01

    Spectral features of non-opioid analgesic drug flupirtine have been explored by the Fourier transform infrared, Raman and Nuclear magnetic resonance spectroscopic techniques combined with density functional theory computations. The bioactive conformer of flupirtine is stabilized by an intramolecular Csbnd H⋯N hydrogen bonding resulting by the steric strain of hydrogen atoms. Natural bond orbital and natural population analysis support this result. The charge redistribution also has been analyzed. Antimicrobial activities of flupirtine have been screened by agar well disc diffusion and molecular docking methods, which exposes the importance of triaminopyridine in flupirtine.

  2. Low-Power and Optimized VLSI Implementation of Compact Recursive Discrete Fourier Transform (RDFT Processor for the Computations of DFT and Inverse Modified Cosine Transform (IMDCT in a Digital Radio Mondiale (DRM and DRM+ Receiver

    Directory of Open Access Journals (Sweden)

    Sheau-Fang Lei

    2013-05-01

    Full Text Available This paper presents a compact structure of recursive discrete Fourier transform (RDFT with prime factor (PF and common factor (CF algorithms to calculate variable-length DFT coefficients. Low-power optimizations in VLSI implementation are applied to the proposed RDFT design. In the algorithm, for 256-point DFT computation, the results show that the proposed method greatly reduces the number of multiplications/additions/computational cycles by 97.40/94.31/46.50% compared to a recent approach. In chip realization, the core size and chip size are, respectively, 0.84 × 0.84 and 1.38 × 1.38 mm2. The power consumption for the 288- and 256-point DFT computations are, respectively, 10.2 (or 0.1051 and 11.5 (or 0.1176 mW at 25 (or 0.273 MHz simulated by NanoSim. It would be more efficient and more suitable than previous works for DRM and DRM+ applications.

  3. Complex of manganese (II) with curcumin: Spectroscopic characterization, DFT study, model-based analysis and antiradical activity

    Science.gov (United States)

    Gorgannezhad, Lena; Dehghan, Gholamreza; Ebrahimipour, S. Yousef; Naseri, Abdolhossein; Nazhad Dolatabadi, Jafar Ezzati

    2016-04-01

    The complex formation between curcumin (Cur) and Manganese (II) chloride tetrahydrate (MnCl2.4H2O) was studied by UV-Vis and IR spectroscopy. Spectroscopic data suggest that Cur can chelate Manganese cations. A simple multi-wavelength model-based method was used to define stability constant for complexation reaction regardless of the spectra overlapping of components. Also, pure spectra and concentration profiles of all components were extracted using this method. Density functional theory (DFT) was also used to view insight into complexation mechanism. Antioxidant activity of Cur and Cur-Mn(II) complex was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging method. Bond dissociation energy (BDE), the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and Molecular electrostatic potential (MEP) of Cur and the complex also were calculated at PW91/TZ2P level of theory using ADF 2009.01 package. The experimental results show that Cur has a higher DPPH radical scavenging activity than Cur-Mn(II). This observation is theoretically justified by means of lower BDE and higher HOMO and LUMO energy values of Cur ligand as compared with those of Cur-Mn(II) complex.

  4. A DFT-based toxicity QSAR study of aromatic hydrocarbons to Vibrio fischeri: Consideration of aqueous freely dissolved concentration.

    Science.gov (United States)

    Wang, Ying; Yang, Xianhai; Wang, Juying; Cong, Yi; Mu, Jingli; Jin, Fei

    2016-05-05

    In the present study, quantitative structure-activity relationship (QSAR) techniques based on toxicity mechanism and density functional theory (DFT) descriptors were adopted to develop predictive models for the toxicity of alkylated and parent aromatic hydrocarbons to Vibrio fischeri. The acute toxicity data of 17 aromatic hydrocarbons from both literature and our experimental results were used to construct QSAR models by partial least squares (PLS) analysis. With consideration of the toxicity process, the partition of aromatic hydrocarbons between water phase and lipid phase and their interaction with the target biomolecule, the optimal QSAR model was obtained by introducing aqueous freely dissolved concentration. The high statistical values of R(2) (0.956) and Q(CUM)(2) (0.942) indicated that the model has good goodness-of-fit, robustness and internal predictive power. The average molecular polarizability (α) and several selected thermodynamic parameters reflecting the intermolecular interactions played important roles in the partition of aromatic hydrocarbons between the water phase and biomembrane. Energy of the highest occupied molecular orbital (E(HOMO)) was the most influential descriptor which dominated the toxicity of aromatic hydrocarbons through the electron-transfer reaction with biomolecules. The results demonstrated that the adoption of freely dissolved concentration instead of nominal concentration was a beneficial attempt for toxicity QSAR modeling of hydrophobic organic chemicals.

  5. Hetarylazopyrazolone Dyes Based on Benzothiazole and Benzimidazole Ring Systems: Synthesis, Spectroscopic Investigation, and Computational Study

    Directory of Open Access Journals (Sweden)

    Ebru Aktan

    2017-01-01

    Full Text Available In this study, the synthesized coupling component 1-(2-benzothiazolyl-3-methylpyrazol-5-one reacted with diazotised heterocyclic amines to afford six novel hetarylazopyrazolone dyes. These azo dyes based on benzothiazole and benzimidazole ring systems were characterized by spectral methods and elemental analyses. The solvatochromic behaviors of these dyes in various solvents were evaluated. The ground state geometries of the dyes were optimized using density functional theory (DFT. Solvent, acid-base, and substituent influences on the wavelength of the maximum absorption were examined in detail. Time-dependent density functional theory (TD-DFT calculations were performed to obtain the absorption spectra of the dyes in various solvents and the results compared with experimental values. Besides, frontier molecular orbitals (FMO analysis for the dyes is also described from the computational process.

  6. Teaching Inorganic Photophysics and Photochemistry with Three Ruthenium(II) Polypyridyl Complexes: A Computer-Based Exercise

    Science.gov (United States)

    Garino, Claudio; Terenzi, Alessio; Barone, Giampaolo; Salassa, Luca

    2016-01-01

    Among computational methods, DFT (density functional theory) and TD-DFT (time-dependent DFT) are widely used in research to describe, "inter alia," the optical properties of transition metal complexes. Inorganic/physical chemistry courses for undergraduate students treat such methods, but quite often only from the theoretical point of…

  7. Multi-conformer molecules in solutions: an NMR-based DFT/MP2 conformational study of two glucopyranosides of a vitamin E model compound.

    Science.gov (United States)

    Nazarski, Ryszard B; Wałejko, Piotr; Witkowski, Stanisław

    2016-03-21

    Overall conformations of both anomeric per-O-acetylated glucosyl derivatives of 2,2,5,7,8-pentamethylchroman-6-ol were studied in the context of their high flexibility, on the basis of NMR spectra in CDCl3 solution and related DFT calculation results. A few computational protocols were used, including diverse density functional/basis set combinations with a special emphasis on accounting (at various steps of the study) for the impact of intramolecular London-dispersion (LD) effects on geometries and relative Gibbs free energies (ΔGs) of different conformers coexisting in solution. The solvent effect was simulated by an IEF-PCM approach with the UFF radii; its other variants, including the use of the recently introduced IDSCRF radii, were employed for a few compact B3LYP-GD3BJ optimized structures showing one small imaginary vibrational frequency. The advantage of using IDSCRF radii for such purposes was shown. Of the four tested DFT methods, only the application of the B3LYP/6-31+G(d,p) approximation afforded ensembles of 7-8 single forms for which population-average values of computed NMR parameters (δH, δC and some (n)JHH data) were in close agreement with those measured experimentally; binuclear (δH,C 1 : 1) correlations, rH,C(2) = 0.9998. The associated individual ΔG values, corrected for LD interactions by applying Grimme's DFT-D3 terms, afforded relative contents of different contributors to the analyzed conformational families in much better agreement with pertinent DFT/NMR-derived populations (i.e., both data sets were found to be practically equal within the limits of estimated errors) than those calculated from dispersion uncorrected ΔGs. All these main findings were confirmed by additional results obtained at the MP2 level of theory. Various other aspects of the study such as the crystal vs. solution structure, gg/gt rotamer ratio, diagnostic (de)shielding effects, dihydrogen C-H···H-C contacts, and doubtful applicability of some specialized

  8. DFT computational study on the phosphate functionalized SWCNTs as efficient drug delivery systems for anti-osteoporosis zolendronate and risedronate drugs

    Science.gov (United States)

    Nikfar, Zahra; Shariatinia, Zahra

    2017-07-01

    The pristine (4,4)-armchair SWCNT as well as its three phosphate functionalized (CNT-nH2PO4, n=1-3) forms were studied as novel drug delivery systems for the two commercially famous anti-osteoporosis drugs including risedronate (RIS) and zolendronate (ZOL) using the density functional theory (DFT) computations at both B3LYP and B3PW91 levels. Results revealed that the binding energy was increased by increasing number of H2PO4 moieties attached on the CNT with the most negative binding energy was measured for the CNT-3H2PO4 carrier. The dipole moments of all phosphate containing CNTs were much greater ( 1.5-4.5 D) than that of pristine CNT ( 0 D). The contour maps verified that when the CNT was functionalized by H2PO4 groups, the symmetric distribution of electric charge was vanished so that the highest and the lowest asymmetric charge distributions were achieved for the CNT-2H2PO4 and CNT-3H2PO4, respectively, leading to the greatest and the smallest dipole moments for the CNT-2H2PO4 (4.177 D) and the CNT-3H2PO4 (1.614 D). The compounds RIS-CNT-3H2PO4 and ZOL-CNT-3H2PO4 displayed the greatest electronegativity and electrophilicity index which were appropriate for the binding of drugs onto the bone surface (having partial positive charge due to the presence of Ca2+) and therefore effectively inhibiting the osteoporosis. Consequently, it was proposed that the drug-CNT-3H2PO4 was the most appropriate drug-carrier system for both of the RIS and ZOL drugs which could be employed as the most efficient vehicle.

  9. DFT and TDDFT investigation of the Schiff base formed by tacrine and saccharin.

    Science.gov (United States)

    Acar, Nursel; Selçuki, Cenk; Coşkun, Emine

    2017-01-01

    Schiff bases have many chemical and biological applications in medicine and pharmaceuticals due to the presence of an imine group (-C=N-). These bases are used in many different fields of technology, and in photochemistry because of their photochromic properties. Here, the structural and electronic properties of the Schiff base formed by tacrine and saccharin (TacSac) were explored using density functional theory with the B3LYP, M06-2X, M06L, and ωB97XD functionals in combination with the 6-311++G(d,p) basis set. The time-dependent formalism was used at the B3LYP/6-311++G(d,p) level to obtain electronic transitions. The calculations were repeated in an implicit solvent model mimicking water, using the polarizable continuum model in conjunction with a solvation model based on a density approach. The results indicate that TacSac cannot form spontaneously, but can be obtained in mild reactions. However, the resulting Schiff base displays different characteristics to its monomers. It also has the potential for use in photochemical intramolecular charge-transfer systems. Graphical Abstract Intramolecular charge transfer between HOMO and LUMO of TacSac.

  10. Synthesis, spectroscopic characterization, DFT optimization and biological activities of Schiff bases and their metal (II) complexes

    Science.gov (United States)

    Rauf, Abdur; Shah, Afzal; Munawar, Khurram Shahzad; Khan, Abdul Aziz; Abbasi, Rashda; Yameen, Muhammad Arfat; Khan, Asad Muhammad; Khan, Abdur Rahman; Qureshi, Irfan Zia; Kraatz, Heinz-Bernhard; Zia-ur-Rehman

    2017-10-01

    A Novel Schiff base, 3-(((4-chlorophenyl)imino)methyl)benzene-1,2-diol (HL1) was successfully synthesized along with a structurally similar Schiff base 3-(((4-bromophenyl)imino)methyl)benzene-1,2-diol (HL2). Both the Schiff bases were used to synthesize their zinc (II) and cobalt (II) complexes. These compounds were characterized by FTIR, 1H NMR, 13C NMR and elemental analysis. Metal complexes were confirmed by TGA. Crystals of Schiff bases were also characterized by X-ray analysis and experimental parameters were found in line with the theoretical parameters. Quantum mechanical approach was also used to fine useful structural parameters and to ensure the geometry of metal complexes. The photometric behaviors of all the synthesized compounds were investigated in a wide pH range using BR buffers. The appearance of isosbestic points indicated the existence of Schiff bases in more than one isomeric form. Moreover, these compounds were screened for enzyme inhibition; antibacterial, cytotoxic and in vivo antidiabetic activities and compounds were found active against one or other activity. Results indicate that ZnL22 is a good inhibitor of alkaline phosphatase enzyme and possess highest potential against diabetes, blood cholesterol level and cancer cells. This effort just provides preliminary data for some biological properties. Further investigations are required to precisely determine mechanistic pathways of their use towards drug development.

  11. The DFT investigations of the electron injection in hydrazone-based sensitizers

    KAUST Repository

    Al-Sehemi, Abdullah G.

    2012-03-01

    Quantum chemical calculations were carried out by using density functional theory and time-dependant density functional theory at B3LYP/6-31G(d) and TD-B3LYP/6-31G(d) level of theories. The absorption spectra have been computed with and without solvent. The calculated absorption spectra in ethanol, acetonitrile, and methanol are in good agreement with experimental evidences. The absorption spectra are red shifted compared to System1. On the basis of electron injection and electronic coupling constant, we have shed light on the nature of different sensitizers. The coplanarity between the benzene near anchoring group having LUMO and the bridge (N-N) is broken in System6 and System7 that would hamper the recombination process. The electron injection of System2-System10 is superior to System1. The highest electronic coupling constant has been observed for System6 that followed the System7 and System8. The light-harvesting efficiency of all the sensitizers enlarged in acetonitrile and ethanol. The long-range-corrected functional (LC-BLYP), Coulomb-attenuating method (CAM-B3LYP), and BH and HLYP functional underestimate the excitation energies while B3LYP is good to reproduce the experimental data. Moreover, we have investigated the effect of cyanoacetic acid as anchoring group on the electron injection. © 2012 Springer-Verlag.

  12. Inversion based on computational simulations

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, K.M.; Cunningham, G.S.; Saquib, S.S.

    1998-09-01

    A standard approach to solving inversion problems that involve many parameters uses gradient-based optimization to find the parameters that best match the data. The authors discuss enabling techniques that facilitate application of this approach to large-scale computational simulations, which are the only way to investigate many complex physical phenomena. Such simulations may not seem to lend themselves to calculation of the gradient with respect to numerous parameters. However, adjoint differentiation allows one to efficiently compute the gradient of an objective function with respect to all the variables of a simulation. When combined with advanced gradient-based optimization algorithms, adjoint differentiation permits one to solve very large problems of optimization or parameter estimation. These techniques will be illustrated through the simulation of the time-dependent diffusion of infrared light through tissue, which has been used to perform optical tomography. The techniques discussed have a wide range of applicability to modeling including the optimization of models to achieve a desired design goal.

  13. Computation of Difference Grobner Bases

    Directory of Open Access Journals (Sweden)

    Vladimir P. Gerdt

    2012-07-01

    Full Text Available This paper is an updated and extended version of our note \\cite{GR'06} (cf.\\ also \\cite{GR-ACAT}. To compute difference \\Gr bases of ideals generated by linear polynomials we adopt to difference polynomial rings the involutive algorithm based on Janet-like division. The algorithm has been implemented in Maple in the form of the package LDA (Linear Difference Algebra and we describe the main features of the package. Its applications are illustrated by generation of finite difference approximations to linear partial differential equations and by reduction of Feynman integrals. We also present the algorithm for an ideal generated by a finite set of nonlinear difference polynomials. If the algorithm terminates, then it constructs a \\Gr basis of the ideal.

  14. A DFT Scheme for Pneumatic Control Logic in Flow-based Biochips

    OpenAIRE

    Potluri, Seetal; Pop, Paul; Madsen, Jan

    2016-01-01

    Microfluidic flow-based biochips help perform biochemistry at miniaturized scales, thus enabling cost, performance and other benefits. Although biochips are expected to replace biochemical labs, including point-of-care devices, the off-chip pressure actuators and pumps are bulky, thereby limiting them to laboratory environments. To address this issue, recent work has focused on reducing the number of off-chip pressure sources, using on-chip pneumatic control logic circuits fabricated using th...

  15. DFT Description of Intermolecular Forces between 9-Aminoacridines and DNA Base Pairs

    Directory of Open Access Journals (Sweden)

    Sandra Cotes Oyaga

    2013-01-01

    Full Text Available The B3LYP method with 6-31G* basis set was used to predict the geometries of five 9-aminoacridines (9-AA 1(a–e, DNA base pairs, and respective complexes. Polarizabilities, charge distribution, frontier molecular orbital (FMO, and dipole moments were used to analyze the nature of interactions that allow reasonable drug diffusion levels. The results showed that charge delocalization, high polarizabilities, and high dipole moments play an important role in intermolecular interactions with DNA. The interactions of 9-AA 1(a–e with GC are the strongest. 9-AA 1(d displayed the strongest interaction and 9-AA 1(b the weakest.

  16. DFT-Domain Based Single-Microphone Noise Reduction for Speech Enhancement

    DEFF Research Database (Denmark)

    C. Hendriks, Richard; Gerkmann, Timo; Jensen, Jesper

    for speech enhancement comprises a history of more than 30 years of research. In this survey, we wish to demonstrate the significant advances that have been made during the last decade in the field of discrete Fourier transform domain-based single-channel noise reduction for speech enhancement.......Furthermore, our goal is to provide a concise description of a state-of-the-art speech enhancement system, and demonstrate the relative importance of the various building blocks of such a system. This allows the non-expert DSP practitioner to judge the relevance of each building block and to implement a close...

  17. A Proline-Based Neuraminidase Inhibitor: DFT Studies on the Zwitterion Conformation, Stability and Formation

    Directory of Open Access Journals (Sweden)

    Zhi-Wei Yang

    2009-09-01

    Full Text Available The designs of potent neuraminidase (NA inhibitors are an efficient way to deal with the recent “2009 H1N1” influenza epidemic. In this work, density functional calculations were employed to study the conformation, stability and formation of the zwitterions of 5-[(1R,2S-1-(acetylamino-2-methoxy-2-methylpentyl]-4-[(1Z-1-propenyl]-(4S,5R-D-proline (BL, a proline-based NA inhibitor. Compared to proline, the zwitterion stability of BL is enhanced by 1.76 kcal mol-1 due to the introduction of functional groups. However, the zwitterion of BL will not represent a local minimum on the potential energy surface until the number of water molecules increases up to two (n = 2. With the addition of two and three water molecules, the energy differences between the zwitterions and corresponding canonical isomers were calculated at 3.13 and -1.54 kcal mol-1, respectively. The zwitterions of BL are mainly stabilized by the H-bonds with the water molecules, especially in the case of three water molecules where the carboxyl-O atoms are largely coordination-saturated by three H-bonds of medium strengths, causing the zwitterion stability even superior to the canonical isomer. With the presence of two and three water molecules, the energy barriers for the conversion processes from the canonical isomers to the zwitterions are equal to 4.96 and 3.13 kcal mol-1, respectively. It indicated that the zwitterion formation is facile to take place with addition of two molecules and further facilitated by more water molecules. Besides, the zwitterion formation of BL is finished in a single step, different from other NA inhibitors. Owing to the above advantages, BL is a good NA inhibitor candidate and more attention should be paid to explorations of BL-based drugs.

  18. DFT-based simulations of amide I' IR spectra of a small protein in solution using empirical electrostatic map with a continuum solvent model.

    Science.gov (United States)

    Welch, William R W; Kubelka, Jan

    2012-09-01

    A continuum solvent model was tested for simulations of amide I' IR spectra for a 40-residue subdomain of P22 viral coat protein in aqueous solution. Spectra obtained using DFT (BPW91/6-31G**) parameters for a reduced all-Ala representation of the protein were corrected by an electrostatic potential map obtained from the solvent cavity surface and AMBER99 side-chain atom partial charges. Various cavity sizes derived from van der Waals atomic radii with an added effective solvent radius up to 2.0 Å were tested. The interplay of the side-chain and solvent electrostatic effects was investigated by considering the side chains and solvent separately as well as together. The sensitivity to side-chain conformational fluctuations and to the parametrization of C(β) group partial charges was also tested. Simulation results were compared to the experimental amide I' spectra of P22 subdomain, including two (13)C isotopically edited variants, as well as to the previous simulations based on the molecular dynamics trajectory in explicit solvent. For small cavity sizes, between van der Waals and that with added solvent radius of 0.5 Å, better qualitative agreement with experiment was obtained than with the explicit solvent representation, in particular for the (13)C-labeled spectra. Larger protein cavities led to progressively worse predictions due to increasingly stronger electrostatic effects of side chains, which could no longer be well compensated for by the solvent potential. Balance between side-chain and solvent electrostatic effects is important in determining the width and shape of the simulated amide I', which is also virtually unaffected by side-chain-geometry fluctuations. The continuum solvent model combined with the electrostatic map is a computationally efficient and potentially robust approach for the simulations of IR spectra of proteins in solution.

  19. DFT computational analysis of piracetam

    Science.gov (United States)

    Rajesh, P.; Gunasekaran, S.; Seshadri, S.; Gnanasambandan, T.

    2014-11-01

    Density functional theory calculation with B3LYP using 6-31G(d,p) and 6-31++G(d,p) basis set have been used to determine ground state molecular geometries. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of piracetam is calculated using B3LYP/6-31G(d,p) method on the finite-field approach. The stability of molecule has been analyzed by using NBO/NLMO analysis. The calculation of first hyperpolarizability shows that the molecule is an attractive molecule for future applications in non-linear optics. Molecular electrostatic potential (MEP) at a point in the space around a molecule gives an indication of the net electrostatic effect produced at that point by the total charge distribution of the molecule. The calculated HOMO and LUMO energies show that charge transfer occurs within these molecules. Mulliken population analysis on atomic charge is also calculated. Because of vibrational analysis, the thermodynamic properties of the title compound at different temperatures have been calculated. Finally, the UV-Vis spectra and electronic absorption properties are explained and illustrated from the frontier molecular orbitals.

  20. The rejection of vibrations in adaptive optics systems using a DFT-based estimation method

    Science.gov (United States)

    Kania, Dariusz; Borkowski, Józef

    2016-04-01

    Adaptive optics systems are commonly used in many optical structures to reduce perturbations and to increase the system performance. The problem in such systems is undesirable vibrations due to some effects as shaking of the whole structure or the tracking process. This paper presents a frequency, amplitude and phase estimation method of a multifrequency signal that can be used to reject these vibrations in an adaptive method. The estimation method is based on using the FFT procedure. The undesirable signals are usually exponentially damped harmonic oscillations. The estimation error depends on several parameters and consists of a systematic component and a random component. The systematic error depends on the signal phase, the number of samples N in a measurement window, the value of CiR (number of signal periods in a measurement window), the THD value and the time window order H. The random error depends mainly on the variance of noise and the SNR value. This paper shows research on the sinusoidal signal phase and the estimation of exponentially damped sinusoids parameters. The shape of errors signals is periodical and it is associated with the signal period and with the sliding measurement window. For CiR=1.6 and the damping ratio 0.1% the error was in the order of 10-5 Hz/Hz, 10-4 V/V and 10-4 rad for the frequency, the amplitude and the phase estimation respectively. The information provided in this paper can be used to determine the approximate level of the efficiency of the vibrations elimination process before starting it.

  1. Effect of base stacking on the acid-base properties of the adenine cation radical [A*+] in solution: ESR and DFT studies.

    Science.gov (United States)

    Adhikary, Amitava; Kumar, Anil; Khanduri, Deepti; Sevilla, Michael D

    2008-08-06

    In this study, the acid-base properties of the adenine cation radical are investigated by means of experiment and theory. Adenine cation radical (A*(+)) is produced by one-electron oxidation of dAdo and of the stacked DNA-oligomer (dA)6 by Cl2*(-) in aqueous glass (7.5 M LiCl in H2O and in D2O) and investigated by ESR spectroscopy. Theoretical calculations and deuterium substitution at C8-H and N6-H in dAdo aid in our assignments of structure. We find the pKa value of A*(+) in this system to be ca. 8 at 150 K in seeming contradiction to the accepted value of or = 160 K, complete deprotonation of A*(+) occurs in dAdo in these glassy systems even at pH ca. 3. A*(+) found in (dA)6 at 150 K also deprotonates on thermal annealing. The stability of A*(+) at 150 K in these systems is attributed to charge delocalization between stacked bases. Theoretical calculations at various levels (DFT B3LYP/6-31G*, MPWB95, and HF-MP2) predict binding energies for the adenine stacked dimer cation radical of 12 to 16 kcal/mol. Further DFT B3LYP/6-31G* calculations predict that, in aqueous solution, monomeric A*(+) should deprotonate spontaneously (a predicted pKa of ca. -0.3 for A*(+)). However, the charge resonance stabilized dimer AA*(+) is predicted to result in a significant barrier to deprotonation and a calculated pKa of ca. 7 for the AA*(+) dimer which is 7 pH units higher than the monomer. These theoretical and experimental results suggest that A*(+) isolated in solution and A*(+) in adenine stacks have highly differing acid-base properties resulting from the stabilization induced by hole delocalization within adenine stacks.

  2. DFT-based simulations of IR amide I' spectra for a small protein in solution. Comparison of explicit and empirical solvent models.

    Science.gov (United States)

    Grahnen, Johan A; Amunson, Krista E; Kubelka, Jan

    2010-10-14

    Infrared (IR) amide I' spectra are widely used for investigations of the structural properties of proteins in aqueous solution. For analysis of the experimental data, it is necessary to separate the spectral features due to the backbone conformation from those arising from other factors, in particular the interaction with solvent. We investigate the effects of solvation on amide I' spectra for a small 40-residue helix-turn-helix protein by theoretical simulations based on density functional theory (DFT). The vibrational force fields and intensity parameters for the protein amide backbone are constructed by transfer from smaller heptaamide fragments; the side chains are neglected in the DFT calculations. Solvent is modeled at two different levels: first as explicit water hydrogen bonded to the surface amide groups, treated at the same DFT level, and, second, using the electrostatic map approach combined with molecular dynamics (MD) simulation. Motional narrowing of the spectral band shapes due to averaging over the fast solvent fluctuation is introduced by use of the time-averaging approximation (TAA). The simulations are compared with the experimental amide I', including two (13)C isotopically edited spectra, corrected for the side-chain signals. Both solvent models are consistent with the asymmetric experimental band shape, which arises from the differential solvation of the amide backbone. However, the effects of (13)C isotopic labeling are best captured by the gas-phase calculations. The limitations of the solvent models and implications for the theoretical simulations of protein amide vibrational spectra are discussed.

  3. Synthesis, Characterization, Properties and DFT Calculations of 2-(Benzo[b]thiophen-2-yl)pyridine-based Iridium(III) Complexes with Different Ancillary Ligands.

    Science.gov (United States)

    Li, Gao-Nan; Zeng, Yong-Pi; Li, Kai-Xiu; Chen, Hao-Hua; Xie, Hui; Zhang, Fu-Lin; Chen, Guang-Ying; Niu, Zhi-Gang

    2016-01-01

    A series of new cyclometalated btp-based iridium(III) complexes with three different ancillary ligands, Ir(btp)2(bozp) (3a), Ir(btp)2(btzp) (3b) and Ir(btp)2(izp) (3c) (btp = 2-(benzo[b]thiophen-2-yl)pyridine, bozp =2-(benzo[d]oxazol-2-yl)phenol, btzp =2-(benzo[d]thiazol-2-yl)phenol, izp = 2-(2 H-indazol-2-yl)phenol), have been synthesized and fully characterized. The crystal structure of 3b has been determined by single crystal X-ray diffraction analysis. A comparative study has been carried out for complexes 3a - 3c by UV-vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry and DFT calculations. This observation illustrates that the substitution of N or S in ancillary ligand can lead to a marked bathochromic shift of absorption and emission wavelengths. The spectroscopic characterisation of these complexes has been complemented by DFT and TD-DFT calculations, supporting the assignment of (3)MLCT/(3)LC to the lowest energy excited state.

  4. Versatile and green synthesis, spectroscopic characterizations, crystal structure and DFT calculations of 1,2,3‒triazole‒based sulfonamides

    Science.gov (United States)

    Saeidian, Hamid; Sadighian, Hamed; Abdoli, Morteza; Sahandi, Morteza

    2017-03-01

    A green, and practically reliable method for the synthesis of novel 1,2,3‒triazole-based sulfonamides via copper (I)‒catalyzed azide‒alkyne [3 + 2] cycloaddition reaction was reported. The desired products were characterized by CHN analysis, FT-IR, 1H and 13C NMR, ESI-MS spectroscopy, single crystal X-ray diffraction and density functional theory (DFT) geometry optimization and molecular orbital calculations. Mild and green reaction conditions, atom-economic and high yields (61-91%) make this protocol an attractive option for the synthesis of 1,2,3‒triazoles bearing sulfonamide moiety. Geometrical structures, vibrational frequencies, 1H and 13C chemical shift values, Mulliken charge distribution and electrophilicity index (HOMO-LUMO analysis) of the characterized structure of 3f in the ground state have been calculated with the aid of DFT studies. The calculated chemical shifts (NMR) and vibrational frequencies (FT-IR) are in compliance with the experimental findings. The aim of the DFT study was to make a reasonable assignment of vibrational bands and chemical shifts.

  5. Comprehensive Characterization of Palygorskite from Torrejon el Rubio (Spain) Based on Experimental Techniques and Theoretical DFT Studies

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A.M.; Timon, V.; Cubero, J. J.; Sanchez-Ledesma, D. M.; Gutierrez-Nebot, L.; Martinez, J. J.; Romero, C.; Labajo, M.; Melon, A.; Barrios, I.

    2013-10-01

    New data about the physico-chemical, microstructural and crystal-chemical properties of the mineral paligorskite from Torrejon el Rubio (Caceres, Spain) were obtained by a combination of experimental techniques (XRD, FRX, FTIR, TG-DSC, SEM and chemical analyses), as well as geometry optimization by means of the Density Functional Theory (DFT). This study demonstrates the applicability of the mixed theoretical-experimental work to characterize and understand the properties of clay minerals used in technological applications and environmental remediation. (Author)

  6. Computer-Based Linguistic Analysis.

    Science.gov (United States)

    Wright, James R.

    Noam Chomsky's transformational-generative grammar model may effectively be translated into an equivalent computer model. Phrase-structure rules and transformations are tested as to their validity and ordering by the computer via the process of random lexical substitution. Errors appearing in the grammar are detected and rectified, and formal…

  7. Computer-Based Linguistic Analysis.

    Science.gov (United States)

    Wright, James R.

    Noam Chomsky's transformational-generative grammar model may effectively be translated into an equivalent computer model. Phrase-structure rules and transformations are tested as to their validity and ordering by the computer via the process of random lexical substitution. Errors appearing in the grammar are detected and rectified, and formal…

  8. Synthesis, crystal structure investigation, spectroscopic characterizations and DFT computations on a novel 1-(2-chloro-4-phenylquinolin-3-yl)ethanone

    Science.gov (United States)

    Murugavel, S.; Stephen, C. S. Jacob Prasanna; Subashini, R.; Reddy, H. Raveendranatha; AnanthaKrishnan, Dhanabalan

    2016-10-01

    The title compound 1-(2-chloro-4-phenylquinolin-3-yl)ethanone (CPQE) was synthesised effectively by chlorination of 3-acetyl-4-phenylquinolin-2(1H)-one (APQ) using POCl3 reagent. Structural and vibrational spectroscopic studies were performed by utilizing single crystal X-ray diffraction, FTIR and NMR spectral analysis along with DFT method utilizing GAUSSIAN‧ 03 software. Veda program has been employed to perform a detailed interpretation of vibrational spectra. Mulliken population analyses on atomic charges, MEP, HOMO-LUMO, NBO, Global chemical reactivity descriptors and thermodynamic properties have been examined by (DFT/B3LYP) method with the 6-311G(d,p) basis set level.

  9. Molecular structure, vibrational analysis (FT-IR, FT-Raman), NMR, UV, NBO and HOMO-LUMO analysis of N,N-Diphenyl Formamide based on DFT calculations.

    Science.gov (United States)

    Mathammal, R; Monisha, N R; Yasaswini, S; Krishnakumar, V

    2015-03-15

    In this work, the vibrational spectral analysis is carried out by using Raman and infrared spectroscopy in the range 4000-400 cm(-1) and 4000-50 cm(-1) respectively for N,N-Diphenyl Formamide (DPF) molecule. The optimized molecular structures, vibrational frequencies and corresponding vibrational assignments, nuclear magnetic resonance (NMR) and ultraviolet-visible (UV-VIS) spectra of the title molecule are evaluated using density functional theory (DFT) with standard B3LYP/6-31G(d,p) basis set. The harmonic vibrational frequencies are calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The stability of the molecule arising from hyper conjugative interactions and the charge delocalization has been analyzed using natural bond (NBO) analysis. The possible electronic transitions are determined by HOMO-LUMO orbital shapes and their energies. Thermodynamic properties (heat capacity, entropy and enthalpy) and the first hyperpolarizability of the title compound are calculated. The Mulliken charges and electric dipole moment of the molecule are computed using DFT calculations. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shift of the molecules are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. TD-DFT Investigation of the Magnetic Circular Dichroism Spectra of Some Purine and Pyrimidine Bases of Nucleic Acids

    DEFF Research Database (Denmark)

    Fahleson, Tobias; Kauczor, Joanna; Norman, Patrick

    2015-01-01

    We present a computational study of the magnetic circular dichroism (MCD) spectra in the 200–300 nm wavelength region of purine and its derivative hypoxanthine, as well as of the pyrimidine bases of nucleic acids uracil, thymine, and cytosine, using the B3LYP and CAM–B3LYP functionals. Solvent...... effects are investigated within the polarizable continuum model and by inclusion of explicit water molecules. In general, the computed spectra are found to be in good agreement with the experimental ones, apart from some overall blue shifts. Both the pseudo-A term shape of the MCD spectra of the purines...... and the B term shape of the spectra of pyrimidine bases are reproduced. Our calculations also correctly reproduce the reversed phase of the MCD bands in purine compared to that of its derivatives present in nucleic acids. Solvent effects are sizable and system specific, but they do not in general alter...

  11. A new copper(II) Schiff base complex containing asymmetrical tetradentate N2O2 Schiff base ligand: Synthesis, characterization, crystal structure and DFT study

    Science.gov (United States)

    Grivani, Gholamhossein; Baghan, Sara Husseinzadeh; Vakili, Mohammad; Khalaji, Aliakbar Dehno; Tahmasebi, Vida; Eigner, Václav; Dušek, Michal

    2015-02-01

    A new copper (II) Schiff base complex, CuL1, was prepared from the reaction of asymmetrical Schiff base ligand of L1 and Cu(OAC)2 (L1 = salicylidene imino-ethylimino-pentan-2-one). The Schiff base ligand, L1, and its copper (II) complex, CuL1, have been characterized by elemental analysis (CHN) and FT-IR and UV-vis spectroscopy. In addition, 1H NMR was employed for characterization of the ligand. Thermogrametric analysis of the CuL1 reveals its thermal stability and its decomposition pattern shows that it is finally decomposed to the copper oxide (CuO). The crystal structure of CuL1 was determined by the single crystal X-ray analysis. The CuL1 complex crystallizes in the monoclinic system, with space group P21/n and distorted square planar coordination around the metal ion. The Schiff base ligand of L1 acts as a chelating ligand and coordinates via two nitrogen and two oxygen atoms to the copper (II) ion with C1 symmetry. The structure of the CuL1 complex was also studied theoretically at different levels of DFT and basis sets. According to calculated results the Csbnd O bond length of the salicylate fragment is slightly higher than that in the acetylacetonate fragment of ligand, which could be interpreted by resonance increasing between phenyl and chelated rings in ligand in relative to the acetylacetonate fragment.

  12. Web-Based Computing Resource Agent Publishing

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Web-based Computing Resource Publishing is a efficient way to provide additional computing capacity for users who need more computing resources than that they themselves could afford by making use of idle computing resources in the Web.Extensibility and reliability are crucial for agent publishing. The parent-child agent framework and primary-slave agent framework were proposed respectively and discussed in detail.

  13. Link-Level Performance Analysis of DFT-S-OFDM System based on Turbo Equalization%基于Turbo均衡的DFT-S-OFDM系统的链路性能仿真

    Institute of Scientific and Technical Information of China (English)

    王东明

    2008-01-01

    为了克服离散傅立叶变换扩展的正交频分复用(DFT-S-OFDM)中存在的符号间干扰,提出频域最小均方误差的Turbo均衡算法.并给出采用3GPP长期演进中DFT-S-OFDM系统的链路性能分析.通过仿真可以看到,Turbo均衡可以明显改善系统的误帧性能.

  14. Novel butyrylcholinesterase inhibitors through pharmacophore modeling, virtual screening and DFT-based approaches along-with design of bioisosterism-based analogues.

    Science.gov (United States)

    Gogoi, Dhrubajyoti; Chaliha, Amrita Kashyap; Sarma, Diganta; Kakoti, Bibhuti Bhusan; Buragohain, Alak Kumar

    2017-01-01

    Ligand and structure-based pharmacophore models were used to identify the important chemical features of butyrylcholinesterase (BChE) inhibitors. A training set of 16 known structurally diverse compounds with a wide range of inhibitory activity against BChE was used to develop a quantitative ligand-based pharmacophore (Hypo1) model to identify novel BChE inhibitors in virtual screening databases. A structure-based pharmacophore hypothesis (Phar1) was also developed with the ligand-binding site of BChE in consideration. Further, the models were validated using test set, Fisher's Randomization and Leave-one-out validation methods. Well-validated pharmacophore hypotheses were further used as 3D queries in virtual screening and 430 compounds were finally selected for molecular docking analysis. Subsequently, ADMET, DFT and chemical similarity search were employed to narrow down on seven compounds as potential drug candidates. Analogues of the best hit were further developed through a bioisosterism-guided approach to further generate a library of potential BChE inhibitors.

  15. 基于Matlab的DFT及FFT频谱分析%Spectrum Analysis of DFT and FFT Based on Matlab

    Institute of Scientific and Technical Information of China (English)

    刘小群; 周云波

    2010-01-01

    DFT及FFT是数字信号处理的重要内容.DFT是FFT的基础,FFT是DFT的快速算法,在MATLAB中可以利用函数FFT来计算序列的离散傅里叶变换DFT.基于此首先介绍了Matlab软件;其次给出了基于Matlab软件的DFT和FFT频谱分析的方法,利用Matlab软件方法,使得设计方便、快捷,大大减轻了工作量;最后结合实例给出了仿真结果.

  16. COMPUTER BASED HEART PULSES MEASUREMENT

    Directory of Open Access Journals (Sweden)

    Ali N. Hamoodi

    2013-05-01

    Full Text Available In this work the measurement and displays of blood oxygen saturation and pulse rate are investigated practically using computer.The analysis involves the variation in blood oxygen saturation ratio and pulse rate. The results obtained are compared with kontron pulse oximeter 7840 device. The value obtained for the same person pulse rate is approximately equal to that obtained by the konton pulse oximeter 7840 device. The sensor used in this work is the finger clip.The advantages of using computer over kontron pulse oximeter 7840 device is that the data of the patient can be saved in the computer for many years and also it can be display at any time so that the doctor get file contains all data for each patient. 

  17. A novel algorithm for computer based assessment

    OpenAIRE

    2012-01-01

    Student learning outcomes have been evaluated through graded assignments and tests by most paper-based assessment systems. But computer based assessments has the opportunity to improve the efficiency of assessments process. The use of internet is also made possible

  18. Mechanical and magneto-opto-electronic investigation of transition metal based fluoro-perovskites: An ab-initio DFT study

    Science.gov (United States)

    Erum, Nazia; Azhar Iqbal, Muhammad

    2017-09-01

    Detailed ab-initio calculations are performed to investigate structural, elastic, mechanical, magneto-electronic and optical properties of the KXF3 (X = V, Fe, Co, Ni) fluoro-perovskites using Full Potential Linearized Augmented Plane Wave (FP-LAPW) method within the framework of density functional theory (DFT). The calculated structural parameters by DFT and analytical methods are found consistent with the experimental results. From the elastic and mechanical properties, it can be inferred that these compounds are elastically stable and anisotropic while KCoF3 is harder than rest of the compounds. Furthermore, thermal behavior of these compounds is analyzed by calculating Debye temperature (θD). The calculated spin dependent magneto-electronic properties in these compounds reveal that exchange splitting is dominated by N-3d orbital. The stable magnetic phase optimizations verify the experimental observations at low temperature. Type of chemical bonding is analyzed with the help of variations in electron density difference distribution that is induced due to changes of the second cation. The linear optical properties are also discussed in terms of optical spectra. The present methodology represents an influential approach to calculate the whole set of mechanical and magneto-opto-electronic parameters, which would support to understand various physical phenomena and empower device engineers for implementing these materials in spintronic applications.

  19. A DFT-Based QSARs Study of Acetazolamide/Sulfanilamide Derivatives with Carbonic Anhydrase (CA-II Isozyme Inhibitory Activity

    Directory of Open Access Journals (Sweden)

    Oral Oltulu

    2007-02-01

    Full Text Available This study presents Quantitative Structure Activity Relationships (QSAR studyon a pool of 18 bio-active sulfonamide compounds which includes five acetazolamidederivatives, eight sulfanilamide derivatives and five clinically used sulfonamides moleculesas drugs namely acetazolamide, methazolamide, dichlorophenamide, ethoxolamide anddorzolamide. For all the compounds, initial geometry optimizations were carried out with amolecular mechanics (MM method using the MM force fields. The lowest energyconformations of the compounds obtained by the MM method were further optimized by theDensity Functional Theory (DFT method by employing Becke’s three-parameter hybridfunctional (B3LYP and 6-31G (d basis set. Molecular descriptors, dipole moment,electronegativity, total energy at 0 K, entropy at 298 K, HOMO and LUMO energiesobtained from DFT calculations provide valuable information and have a significant role inthe assessment of carbonic anhydrase (CA-II inhibitory activity of the compounds. By usingthe multiple linear regression technique several QSAR models have been drown up with thehelp these calculated descriptors and carbonic anhydrase (CA-II inhibitory data of themolecules. Among the obtained QSAR models presented in the study, statistically the mostsignificant one is a five parameters linear equation with the squared correlation coefficient R2 values of ca. 0.94 and the squared cross-validated correlation coefficient R2CV values of ca. 0.85. The results were discussed in the light of the main factors that influence theinhibitory activity of the carbonic anhydrase (CA-II isozyme.

  20. Immune based computer virus detection approaches

    Institute of Scientific and Technical Information of China (English)

    TAN Ying; ZHANG Pengtao

    2013-01-01

    The computer virus is considered one of the most horrifying threats to the security of computer systems worldwide.The rapid development of evasion techniques used in virus causes the signature based computer virus detection techniques to be ineffective.Many novel computer virus detection approaches have been proposed in the past to cope with the ineffectiveness,mainly classified into three categories:static,dynamic and heuristics techniques.As the natural similarities between the biological immune system (BIS),computer security system (CSS),and the artificial immune system (AIS) were all developed as a new prototype in the community of anti-virus research.The immune mechanisms in the BIS provide the opportunities to construct computer virus detection models that are robust and adaptive with the ability to detect unseen viruses.In this paper,a variety of classic computer virus detection approaches were introduced and reviewed based on the background knowledge of the computer virus history.Next,a variety of immune based computer virus detection approaches were also discussed in detail.Promising experimental results suggest that the immune based computer virus detection approaches were able to detect new variants and unseen viruses at lower false positive rates,which have paved a new way for the anti-virus research.

  1. Distributed measurement-based quantum computation

    CERN Document Server

    Danos, V; Kashefi, E; Panangaden, P; Danos, Vincent; Hondt, Ellie D'; Kashefi, Elham; Panangaden, Prakash

    2005-01-01

    We develop a formal model for distributed measurement-based quantum computations, adopting an agent-based view, such that computations are described locally where possible. Because the network quantum state is in general entangled, we need to model it as a global structure, reminiscent of global memory in classical agent systems. Local quantum computations are described as measurement patterns. Since measurement-based quantum computation is inherently distributed, this allows us to extend naturally several concepts of the measurement calculus, a formal model for such computations. Our goal is to define an assembly language, i.e. we assume that computations are well-defined and we do not concern ourselves with verification techniques. The operational semantics for systems of agents is given by a probabilistic transition system, and we define operational equivalence in a way that it corresponds to the notion of bisimilarity. With this in place, we prove that teleportation is bisimilar to a direct quantum channe...

  2. 基于DCT和DFT视频盲水印算法的研究与实现%Research and Implementation on Blind Video Watermarking Algorithms Based on DCT and DFT

    Institute of Scientific and Technical Information of China (English)

    丁海洋

    2012-01-01

    为了统计不同算法的透明性和鲁棒性,比较不同算法的优缺点,针对基于DCT和DFT的视频盲水印算法进行了研究。研究并实现了3种基于DCT的视频水印算法和1种基于DFT的视频水印算法。通过实验,统计它们的透明性和鲁棒性。结果表明,DCT算法的透明性优于DFT算法;DFT算法抗几何攻击的鲁棒性优于DCT算法,DCT算法抗编码攻击的鲁棒性优于DFT算法。%Video watermark is an emerging technology for copyright protection and authentication of digital video, this paper has researched and realized blind video watermarking algorithms based on DCT and DFT, Studied and implemented three kinds of DCT-based video watermark algorithms and one DFT-based video watermark algorithm, and counted transparency and robustness of algorithms. Experiments show that the transparency of DCT algorithms is superior to the DFT algorithm; and the robustness of the DFT algorithm against ge- ometrical attacks is better than DCT algorithms, the robustness of DCT algorithms against coding attacks is better than the DFT algorithm.

  3. A DFT Computation for Comparison of NQR of O2, N2 and CO over the Surface of Single-Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    A.S. Ghasemi

    2013-02-01

    Full Text Available In this study we assumed Single-Walled Carbon Nano Tubes (SWCNTs as ideal candidates for various applications of gas sensors due to their amazing physical adsorption properties. The adsorption behavior of selected nitrogen, oxygen and CO molecules on the surface of the Single-Walled Carbon Nano Tubes (SWCNTs was studied by the Density Functional Theory (DFT (B3LYP/6-311G* using the Gaussian 98 software. We studied the Nuclear Quadrupole Resonance (NQR of the armchair (4, 4 SWCNTs with the optimal diameter of 5.6 Å and the length of 9.8 Å. For the first time, DFT calculations were performed to calculate oxygen and nitrogen the interaction of quadrupole moment with Electric Field Gradient (EFG in NQR in the representative considered model of the (N2-CNTs, (O2-CNTs and (CO-CNTs. The evaluated NQR parameters reveal that the EFG tensors of Oxygen-17, Nitrogen-14 and Carbon-13 are influenced and show particular trends from gas molecules in the SWCNTs due to the contribution of N-N, O-O and C-O gas molecules of SWCNTs.

  4. 基于DFT算法的单相数字锁相环%Single-phase Digital Phase-locked Loop Based on DFT

    Institute of Scientific and Technical Information of China (English)

    赵文才; 范声芳; 熊健; 张凯

    2011-01-01

    离散傅里叶变换(DFT)算法可以方便提取信号的幅值和相位,通过仿真和理论推导,深入分析基于傅里叶变换(FFT)的锁相环,并研究了其数字实现方法,即基于DFT算法的锁相环.此锁相方式在同步信号中有谐波或多个过零点时仍能正常工作,有较高的精度.仿真和实验结果证明该技术是可靠可行的.%DFT algorithm can easily extract amplitude and phase of the signal. This paper analyzes the phase-locked loop based on FFT through simulation and theoretical analysis ,and discusses the digital implementation of it. This method can work reliably even when the synchronization signal has harmonics or multi-zero-crossing, and it also has high precision.Simulation and experimental results validate its feasibility.

  5. TD-DFT investigation of the magnetic circular dichroism spectra of some purine and pyrimidine bases of nucleic acids.

    Science.gov (United States)

    Fahleson, Tobias; Kauczor, Joanna; Norman, Patrick; Santoro, Fabrizio; Improta, Roberto; Coriani, Sonia

    2015-05-28

    We present a computational study of the magnetic circular dichroism (MCD) spectra in the 200-300 nm wavelength region of purine and its derivative hypoxanthine, as well as of the pyrimidine bases of nucleic acids uracil, thymine, and cytosine, using the B3LYP and CAM-B3LYP functionals. Solvent effects are investigated within the polarizable continuum model and by inclusion of explicit water molecules. In general, the computed spectra are found to be in good agreement with the experimental ones, apart from some overall blue shifts. Both the pseudo-A term shape of the MCD spectra of the purines and the B term shape of the spectra of pyrimidine bases are reproduced. Our calculations also correctly reproduce the reversed phase of the MCD bands in purine compared to that of its derivatives present in nucleic acids. Solvent effects are sizable and system specific, but they do not in general alter the qualitative shape of the spectra. The bands are dominated by the bright π → π* transitions, and our calculations in solution nicely reproduce their energy differences, improving the estimates obtained in the gas phase. Shoulders are predicted for purine and uracil due to n → π* excitations, but they are too weak to be observed in the experiment.

  6. 基于同步旋转变换及DFT的SVG指令电流检测法%A reference current detection method based on synchronous reference frame transformation and DFT for SVG

    Institute of Scientific and Technical Information of China (English)

    陈丽兵; 史丽萍; 夏正龙; 王攀攀

    2014-01-01

    为使静止无功发生器(Static Var Generator,SVG)具备无功、谐波及不对称电流综合补偿能力,提出了一种基于同步旋转坐标变换及离散傅立叶变换(Discrete Fourier Transform,DFT)的SVG指令电流检测方法。该方法通过在同步旋转坐标系下进行递归离散傅立叶变换,能够实时检测出负载电流中的无功分量、不对称分量以及特征谐波。利用该方法只用一个控制器就能同时对两种特征谐波分量进行补偿,相对于其他方法运算量大大减小,便于工程实现。仿真和实验验证证明了该方法的有效性。%A reference current detection method based on synchronous reference frame transformation and discrete Fourier transform (DFT) is presented to make SVG provide synthetic compensation including reactive power compensation, harmonic compensation and unbalanced current compensation. By using recursive DFT algorithm in the rotating reference frame, the proposed method can be used to extract reactive currents, unbalanced currents and characteristic harmonic currents from the load currents in real time. This method allows the simultaneous compensation of two current harmonics with just one regulator, yielding a significant reduction of the computational effort and easy engineering implementation compared with other methods. The results of simulation and experiment show the validity of this method.

  7. Reversible Data Hiding Based on DNA Computing

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2017-01-01

    Full Text Available Biocomputing, especially DNA, computing has got great development. It is widely used in information security. In this paper, a novel algorithm of reversible data hiding based on DNA computing is proposed. Inspired by the algorithm of histogram modification, which is a classical algorithm for reversible data hiding, we combine it with DNA computing to realize this algorithm based on biological technology. Compared with previous results, our experimental results have significantly improved the ER (Embedding Rate. Furthermore, some PSNR (peak signal-to-noise ratios of test images are also improved. Experimental results show that it is suitable for protecting the copyright of cover image in DNA-based information security.

  8. Game based learning for computer science education

    NARCIS (Netherlands)

    Schmitz, Birgit; Czauderna, André; Klemke, Roland; Specht, Marcus

    2011-01-01

    Schmitz, B., Czauderna, A., Klemke, R., & Specht, M. (2011). Game based learning for computer science education. In G. van der Veer, P. B. Sloep, & M. van Eekelen (Eds.), Computer Science Education Research Conference (CSERC '11) (pp. 81-86). Heerlen, The Netherlands: Open Universiteit.

  9. Game based learning for computer science education

    NARCIS (Netherlands)

    Schmitz, Birgit; Czauderna, André; Klemke, Roland; Specht, Marcus

    2011-01-01

    Schmitz, B., Czauderna, A., Klemke, R., & Specht, M. (2011). Game based learning for computer science education. In G. van der Veer, P. B. Sloep, & M. van Eekelen (Eds.), Computer Science Education Research Conference (CSERC '11) (pp. 81-86). Heerlen, The Netherlands: Open Universiteit.

  10. Achievements of DFT for the investigation of graphene-related nanostructures.

    Science.gov (United States)

    Botello-Méndez, Andrés R; Dubois, Simon M-M; Lherbier, Aurélien; Charlier, Jean-Christophe

    2014-11-18

    CONSPECTUS: Graphene-related nanostructures stand out as exceptional materials due to both their wide range of properties and their expanse of interest in both applied and fundamental research. They are good examples of nanoscale materials for which the properties do not necessarily replicate those of the bulk. For the description and the understanding of their properties, it is clear that a general quantum-mechanical approach is mandatory. The remarkable result of density functional theory (DFT) is that the quantum-mechanical description of materials at the ground state is made amenable to simulations at a relatively low computational cost. The knowledge of materials has undergone a revolution after the introduction of DFT as an unrivaled instrument for the investigation of materials properties through computer experiments. Their deeper understanding comes from a variety of tools developed from concepts intrinsically present in DFT, notably the total energy and the charge density. Such tools allow the prediction of a diverse set of physicochemical properties relevant for material scientists. This Account lays out an example-driven tour through the achievements of ground-state DFT applied to the description of graphene-related nanostructures and to the deep understanding of their outstanding properties. After a brief introduction to DFT, the survey starts with the determination of the most basic properties that can be obtained from DFT, that is, band structures, lattice parameters, and spin ground state. Next follows an exploration of how total energies of different systems can give information about relative stability, formation energies, and reaction paths. Exploiting the derivatives of the energy with respect to displacements leads the way toward the extraction of vibrational and mechanical properties. In addition, a close examination of the charge density gives information about charge transfer mechanisms, which can be linked to chemical reactivity. The ground

  11. Synthesis, spectroscopic studies, DFT calculations, electrochemical evaluation, BSA binding and molecular docking of an aroylhydrazone -based cis-dioxido Mo(VI) complex

    Science.gov (United States)

    Mohamadi, Maryam; Faghih-Mirzaei, Ehsan; Ebrahimipour, S. Yousef; Sheikhshoaie, Iran; Haase, Wolfgang; Foro, Sabine

    2017-07-01

    A cis-dioxido Mo(VI) complex, [MoO2(L)(MeOH)], [L2-: (3-methoxy-2-oxidobenzylidene) benzohydrazonate], has been synthesized and characterized using physicochemical and spectroscopic techniques including elemental analysis, FT-IR, 1HNMR, UV-Vis spectroscopy, molar conductivity and single crystal X-ray diffraction. DFT calculations in the ground state of the complex were carried out using hybrid functional B3LYP with DGDZVP as basis set. Non-linear optical properties including electric dipole moment (μ), polarizability (α) and molecular first hyperpolarizability (β) of the compound were also computed. The values of linear polarizability and first hyperpolarizability obtained for the studied molecule indicated that the compound could be a good candidate of nonlinear optical materials. TD-DFT calculation and molecular electrostatic potential (MEP) were also performed. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the complex at different temperatures have been calculated. The interaction of a synthesized complex, with bovine serum albumin was also thoroughly investigated using experimental and theoretical studies. UV-Vis absorption and fluorescence quenching techniques were used to determine the binding parameters as well as the mechanism of the interaction. The values of binding constants were in the range of 104-105 M-1 demonstrating a moderate interaction between the synthesized complex and BSA making the protein suitable for transportation and delivery of the compound. Thermodynamic parameters were also indicating a binding through van der Waals force or hydrogen bond of [MoO2(L)(MeOH)] to BSA. The results obtained from docking studies were consistent to those obtained from experimental studies.

  12. Spectroscopy studies on Schiff base N,N‧-bis(salicylidene)-1,2-phenylenediamine by NMR, infrared, Raman and DFT calculations

    Science.gov (United States)

    de Toledo, T. A.; Pizani, P. S.; da Silva, L. E.; Teixeira, A. M. R.; Freire, P. T. C.

    2015-10-01

    N,N‧-bis(salicylidene)-1,2-phenylenediamine, also known as Salophen, is a Schiff base which crystallizes in monoclinic structure and space group P21/c, with four molecules per unit cell. It has been intensely studied in last decades because of its excellent properties with many potential applications. In the present study, the structural and vibrational properties of the Salophen were investigated combining scanning electronic microscopy (SEM), Raman, infrared, nuclear magnetic resonance (NMR) spectroscopy as experimental techniques and theoretical calculation based on density functional theory (DFT). The interpretation of the vibrational modes was carried out by means of potential energy distribution (PED). The theoretical results are in good agreement with experimental ones.

  13. Snapshot Based Virtualization Mechanism for Cloud Computing

    Directory of Open Access Journals (Sweden)

    A.Rupa

    2012-09-01

    Full Text Available Virtualization in cloud computing has been the latest evolutionary technology in current applications of various industries and IT firms are adopting Cloud Technology. The concept of cloud computing was introduced long back. Since its inception there have been many number of new innovations implemented by different experts and researchers etc. Virtualization in cloud computing is very effective approach to gain different operational advantages in cloud computing. In this paper we have proposed the concept of virtualization using Snapshot based Mechanism, where the Memory virtualization and Storage virtualization are discussed in this paper.

  14. QPSO-based adaptive DNA computing algorithm.

    Science.gov (United States)

    Karakose, Mehmet; Cigdem, Ugur

    2013-01-01

    DNA (deoxyribonucleic acid) computing that is a new computation model based on DNA molecules for information storage has been increasingly used for optimization and data analysis in recent years. However, DNA computing algorithm has some limitations in terms of convergence speed, adaptability, and effectiveness. In this paper, a new approach for improvement of DNA computing is proposed. This new approach aims to perform DNA computing algorithm with adaptive parameters towards the desired goal using quantum-behaved particle swarm optimization (QPSO). Some contributions provided by the proposed QPSO based on adaptive DNA computing algorithm are as follows: (1) parameters of population size, crossover rate, maximum number of operations, enzyme and virus mutation rate, and fitness function of DNA computing algorithm are simultaneously tuned for adaptive process, (2) adaptive algorithm is performed using QPSO algorithm for goal-driven progress, faster operation, and flexibility in data, and (3) numerical realization of DNA computing algorithm with proposed approach is implemented in system identification. Two experiments with different systems were carried out to evaluate the performance of the proposed approach with comparative results. Experimental results obtained with Matlab and FPGA demonstrate ability to provide effective optimization, considerable convergence speed, and high accuracy according to DNA computing algorithm.

  15. QPSO-Based Adaptive DNA Computing Algorithm

    Directory of Open Access Journals (Sweden)

    Mehmet Karakose

    2013-01-01

    Full Text Available DNA (deoxyribonucleic acid computing that is a new computation model based on DNA molecules for information storage has been increasingly used for optimization and data analysis in recent years. However, DNA computing algorithm has some limitations in terms of convergence speed, adaptability, and effectiveness. In this paper, a new approach for improvement of DNA computing is proposed. This new approach aims to perform DNA computing algorithm with adaptive parameters towards the desired goal using quantum-behaved particle swarm optimization (QPSO. Some contributions provided by the proposed QPSO based on adaptive DNA computing algorithm are as follows: (1 parameters of population size, crossover rate, maximum number of operations, enzyme and virus mutation rate, and fitness function of DNA computing algorithm are simultaneously tuned for adaptive process, (2 adaptive algorithm is performed using QPSO algorithm for goal-driven progress, faster operation, and flexibility in data, and (3 numerical realization of DNA computing algorithm with proposed approach is implemented in system identification. Two experiments with different systems were carried out to evaluate the performance of the proposed approach with comparative results. Experimental results obtained with Matlab and FPGA demonstrate ability to provide effective optimization, considerable convergence speed, and high accuracy according to DNA computing algorithm.

  16. System-dependent dispersion coefficients for the DFT-D3 treatment of adsorption processes on ionic surfaces.

    Science.gov (United States)

    Ehrlich, Stephan; Moellmann, Jonas; Reckien, Werner; Bredow, Thomas; Grimme, Stefan

    2011-12-09

    Dispersion-corrected density functional theory calculations (DFT-D3) were performed for the adsorption of CO on MgO and C(2) H(2) on NaCl surfaces. An extension of our non-empirical scheme for the computation of atom-in-molecules dispersion coefficients is proposed. It is based on electrostatically embedded M(4)X(4) (M=Na, Mg) clusters that are used in TDDFT calculations of dynamic dipole polarizabilities. We find that the C(MM)(6) dispersion coefficients for bulk NaCl and MgO are reduced by factors of about 100 and 35 for Na and Mg, respectively, compared to the values of the free atoms. These are used in periodic DFT calculations with the revPBE semi-local density functional. As demonstrated by calculations of adsorption potential energy curves, the new C(6) coefficients lead to much more accurate energies (E(ads)) and molecule-surface distances than with previous DFT-D schemes. For NaCl/C(2) H(2) we obtained at the revPBE-D3(BJ) level a value of E(ads) =-7.4 kcal mol(-1) in good agreement with experimental data (-5.7 to -7.1 kcal mol(-1)). Dispersion-uncorrected DFT yields an unbound surface state. For the MgO/CO system, the computed revPBE-D3(BJ) value of E(ads) =-4.1 kcal mol(-1) is also in reasonable agreement with experimental results (-3.0 kcal mol(-1)) when thermal corrections are taken into account. Our new dispersion correction also improves computed lattice constants of the bulk systems significantly compared to plain DFT or previous DFT-D results. The extended DFT-D3 scheme also provides accurate non-covalent interactions for ionic systems without empirical adjustments and is suggested as a general tool in surface science.

  17. Synthesis, click reaction, molecular structure, spectroscopic and DFT computational studies on 3-(2,6-bis(trifluoromethyl)phenoxy)-6-(prop-2-yn-1-yloxy)phthalonitrile

    Science.gov (United States)

    Hasan, Muhammad; Shalaby, Mona

    2016-06-01

    The compound 3-(2,6-bis(trifluoromethyl)phenoxy)-6-(prop-2-yn-1-yloxy)phthalonitrile has been synthesized and confirmed by different characterization techniques such as elemental analysis, IR, UV-vis spectroscopy, and X-ray single-crystal determination. The molecular geometry from X-ray determination of this compound in the ground state has been compared using the Hartree-Fock (HF) and density functional theory (DFT) with the 6-31G(d) basis set. This compound reacted with sugar azide via click reaction to form triazol ring. The synergy between carbohydrate molecule and fluorinated organic compound achieved novel synthetic pathways, properties, and applications in chemistry science.

  18. On computer-based assessment of mathematics

    OpenAIRE

    Pead, Daniel

    2010-01-01

    This work explores some issues arising from the widespread use of computer based assessment of Mathematics in primary and secondary education. In particular, it considers the potential of computer based assessment for testing “process skills” and “problem solving”. This is discussed through a case study of the World Class Tests project which set out to test problem solving skills. The study also considers how on-screen “eAssessment” differs from conventional paper tests and how transferri...

  19. MTA Computer Based Evaluation System.

    Science.gov (United States)

    Brenner, Lisa P.; And Others

    The MTA PLATO-based evaluation system, which has been implemented by a consortium of schools of medical technology, is designed to be general-purpose, modular, data-driven, and interactive, and to accommodate other national and local item banks. The system provides a comprehensive interactive item-banking system in conjunction with online student…

  20. MTA Computer Based Evaluation System.

    Science.gov (United States)

    Brenner, Lisa P.; And Others

    The MTA PLATO-based evaluation system, which has been implemented by a consortium of schools of medical technology, is designed to be general-purpose, modular, data-driven, and interactive, and to accommodate other national and local item banks. The system provides a comprehensive interactive item-banking system in conjunction with online student…

  1. Computational Scenario-based Capability Planning

    CERN Document Server

    Abbass, Hussein; Dam, Helen; Baker, Stephen; Whitacre, James M; Sarker, Ruhul; 10.1145/1389095.1389378

    2009-01-01

    Scenarios are pen-pictures of plausible futures, used for strategic planning. The aim of this investigation is to expand the horizon of scenario-based planning through computational models that are able to aid the analyst in the planning process. The investigation builds upon the advances of Information and Communication Technology (ICT) to create a novel, flexible and customizable computational capability-based planning methodology that is practical and theoretically sound. We will show how evolutionary computation, in particular evolutionary multi-objective optimization, can play a central role - both as an optimizer and as a source for innovation.

  2. 2D-QSPR/DFT studies of aryl-substituted PNP-Cr-based catalyst systems for highly selective ethylene oligomerization.

    Science.gov (United States)

    Tang, Siyang; Liu, Zhen; Zhan, Xingwen; Cheng, Ruihua; He, Xuelian; Liu, Boping

    2014-03-01

    1-Hexene and 1-octene are important comonomers for the synthesis of high performance polyolefins. Recently, various N-substituted Cr-bis(diphenylphosphino)amine (PNP-Cr) catalysts show the potential as excellent candidates for highly selective ethylene trimerization/tetramerization. In this work, a series of aryl-substituted PNP-Cr catalysts were studied by two-dimensional quantitative structure-property relationship (QSPR) method based on density functional theory (DFT) calculations. The heuristic method (HM) and best multi-linear regression (BMLR) were used to establish the best linear regression models to describe the relationship between selectivities and catalyst structures. Both Cr(I) and Cr(II) active site models for ethylene trimerization/tetramerization were considered. It was found that 1) the relativity and stability of the models were increased by using self-defined descriptors based on DFT calculations; 2) Cr(I)/Cr(III) centers were the most plausible active sites for ethylene trimerization, while Cr(II)/Cr(IV) active sites were most possibly responsible for ethylene tetramerization; and 3) the skeleton structures of the PNP-Cr system with good complanation and symmetry were crucial for achieving excellent catalytic selectivity of 1-octene, while the PNP-Cr backbone with a large steric effect on N atom would benefit ethylene trimerization. Six new PNP ligands with high selectivity toward ethylene trimerization/tetramerization were predicted based on descriptor analysis and the best linear regression models providing a good basis for further development of novel catalyst systems with better performance.

  3. Spontaneous activation of CO2 and corrosion pathways on iron surface Fe(100): a quantum mechanical study informed by DFT-based dynamics

    Science.gov (United States)

    Glezakou, V. A.; McGrail, P.; Dang, L. X.

    2009-12-01

    Because of the rapidly increasing interest in technologies for capturing and permanently sequestering CO2 as part of a climate change mitigation strategy, understanding the interaction of CO2 with materials that comprise a sequestration system (steels, cements, silicate minerals, etc.) is of fundamental importance. The majority of models for corrosion of metals involve water-mediated processes, with CO2 dissolved in the aqueous phase playing a minor role in the process. In contrast, recent experiments with mild steels have shown that much greater corrosivity actually occurs in the dense CO2 phase, provided sufficient molecular water is present in the CO2 phase to catalyse certain reactions. In our study, we use DFT-based dynamics to study the internal structure of the the super-critical CO2/(H2O)n system, with n=0-4. While water does not disturb the super-critical CO2 phase, it also gives rise to short-lived CO2...H2O bonds which are likely to facilitate the activation of CO2 on the surface, but otherwise maintains its molecular form. We also use DFT methods to probe the fundamental interactions of CO2 or SO2 and H2O with clean or doped iron surfaces and determine the reactive pathways that lead to CO2 chemisorption, dissociation and further formation of corrosion products in the form of carbonates or sulfites. DFT-based molecular dynamics are employed to sample the configurational space of reactants and products more efficiently. CO2 adsorbs readily on the surface assuming a bent geometry, indicative of charge transfer from the surface to CO2, which closely resembles a CO2- moiety. Once CO2 is adsorbed, it can decompose to adsorbed O+CO, which further reacts with CO2 or SO2 to form corrosion products. Molecularly adsorbed water acts as catalyst to lower these reaction barriers. Clearly, the reactive pathways on the surface are quite different than those in aqueous solution. Battelle operates Pacific Northwest National Laboratory for the US Department of Energy.

  4. Element-Based Computational Model

    Directory of Open Access Journals (Sweden)

    Conrad Mueller

    2012-02-01

    Full Text Available A variation on the data-flow model is proposed to use for developing parallel architectures. While the model is a data driven model it has significant differences to the data-flow model. The proposed model has an evaluation cycleof processing elements (encapsulated data that is similar to the instruction cycle of the von Neumann model. The elements contain the information required to process them. The model is inherently parallel. An emulation of the model has been implemented. The objective of this paper is to motivate support for taking the research further. Using matrix multiplication as a case study, the element/data-flow based model is compared with the instruction-based model. This is done using complexity analysis followed by empirical testing to verify this analysis. The positive results are given as motivation for the research to be taken to the next stage - that is, implementing the model using FPGAs.

  5. Synthesis of a novel methyl(2E)-2-{[N-(2-formylphenyl)(4-methylbenzene) sulfonamido]methyl}-3-(2-methoxyphenyl)prop-2-enoate: Molecular structure, spectral, antimicrobial, molecular docking and DFT computational approaches

    Science.gov (United States)

    Murugavel, S.; Vetri velan, V.; Kannan, Damodharan; Bakthadoss, Manickam

    2017-01-01

    The title compound methyl(2E)-2-{[N-(2-formylphenyl)(4-methylbenzene)sulfonamido] methyl}-3-(2-methoxyphenyl)prop-2-enoate (MFMSM) has been synthesized and single crystals were grown by slow evaporation solution growth technique at room temperature. XRD, FT-IR and NMR spectra of MFMSM in the solid phase were recorded and analyzed. The optimized geometry and vibrational wave numbers were computed using DFT method. The NLO, Mulliken, MEP, HOMO-LUMO energy gap and thermodynamic properties were theoretically predicted. The NBO analysis explained the intramolecular hydrogen bonding. The global chemical reactivity descriptors are calculated for MFMSM and used to predict their relative stability and reactivity. All the calculations were carried out by B3LYP/6-311G (d,p) method. MFMSM has been screened for its antimicrobial activity and found to exhibit antifungal and antibacterial effects. Docking simulation has been performed.

  6. Synthesis, structural characterization and DFT calculation on a square-planar Ni(II) complex of a compartmental Schiff base ligand

    Science.gov (United States)

    Biswas, Surajit; Dolai, Malay; Dutta, Arpan; Ali, Mahammad

    2016-12-01

    Reaction of a symmetric compartmental Schiff-base ligand, (H2L) with nickel(II) perchlorate hexahydrate in 1:1 M ratio in methanol gives rise to a mononuclear nickel(II) compound, NiL (1). The compound has been characterized by C, H, N microanalyses and UV-Vis spectra. The single crystal X-ray diffraction studies reveal a square planar geometry around the Ni(II) center. The compound crystallizes in monoclinic system with space group C2/c with a = 21.6425(6), b = 9.9481(3), c = 13.1958(4) Å, β = 107.728(2)°, V = 2706.16(14) Å3 and Z = 4. Ground state DFT optimization and TDDFT calculations on the ligand and complex were performed to get their UV-Vis spectral pattern.

  7. Inapplicability of exact constraints and a minimal two-parameter generalization to the DFT+U based correction of self-interaction error

    Science.gov (United States)

    Moynihan, Glenn; Teobaldi, Gilberto; O'Regan, David D.

    2016-12-01

    In approximate density-functional theory (DFT), the self-interaction error is an electron delocalization anomaly associated with underestimated insulating gaps. It exhibits a predominantly quadratic energy-density curve that is amenable to correction using efficient, constraint-resembling methods such as DFT + Hubbard U (DFT+U ). Constrained DFT (cDFT) enforces conditions on DFT exactly, by means of self-consistently optimized Lagrange multipliers, and while its use to automate error corrections is a compelling possibility, we show that it is limited by a fundamental incompatibility with constraints beyond linear order. We circumvent this problem by utilizing separate linear and quadratic correction terms, which may be interpreted either as distinct constraints, each with its own Hubbard U type Lagrange multiplier, or as the components of a generalized DFT+U functional. The latter approach prevails in our tests on a model one-electron system, H2+ , in that it readily recovers the exact total energy while symmetry-preserving pure constraints fail to do so. The generalized DFT+U functional moreover enables the simultaneous correction of the total energy and ionization potential, or the correction of either together with the enforcement of Koopmans' condition. For the latter case, we outline a practical, approximate scheme by which the required pair of Hubbard parameters, denoted as U1 and U2, may be calculated from first principles.

  8. Three iodometalate organic-inorganic hybrid materials based on methylene blue cation: Syntheses, structures, properties and DFT calculations

    Science.gov (United States)

    Chai, Wen-Xiang; Lin, Jian; Song, Li; Qin, Lai-Shun; Shi, Hong-Sheng; Guo, Jia-Yu; Shu, Kang-Ying

    2012-08-01

    The functional dye of methylene blue (MB) has been employed for seeking new organic-inorganic hybrid photochromic materials. Although the photochromism has not been observed yet, three iodometalate compounds, namely (MB) (PbI3) (DMF) (1), (MB)4(Cu2I4)2 (2), and (MB)3(Bi2I9) (DMF)2 (3), have been synthesized and characterized. The iodometalate anion features as a [PbI3]∞- chain in 1, a dinuclear unit of Cu2I42- in 2, and a dinuclear unit of Bi2I93- in 3. Due to the synergy of cations and anions, the MB+ cations present supramolecular column stacks in 1 and 3, but a novel supramolecular octamer structure in 2. Their thermogravimetric analyses reveal that the polymeric inorganic anion structure is helpful to increase the stability of cation whereas the discrete structure is adverse. For seeking some clues which is significant to searching new photochromic systems, the density functional theory (DFT) studies have been performed on 1, in which the electronic structure analyses suggests that the stacking mode of cations and anions could be also an important factor influencing the charge transfer between them. In addition, dielectric hysteresis loop testing has been performed on 1 due to its polar space group of Cc.

  9. Crystal structures and electronic properties of BaC2 isomers by theoretical study based on DFT

    Institute of Scientific and Technical Information of China (English)

    FENG Jing; XIAO Bing; CHEN JingChao

    2008-01-01

    Band structures and electronic properties of two BaC2 isomers were calculated by using density functional theory (DFT) properly. The ionic bond features are all typical between cation (Ba) and anion clusters (C2) in both structures of the isomers. However, a much stronger covalent bond exists in anion clusters which can be seen by inspecting the electron distribution contour that has a dull bell like shape between two carbon atoms. The shortest distance between Ba2+ and C22- and the bond length in anion clusters are different in these isomers of BaC2, which are 0.2945 nm and 0.1185 nm for the structure with the 14/mmm space group and 0.2744 and 0.1136 nm with the C2/c type, respectively. Band structures were clarified by combining the DOS to indicate the ionic bonding features more clearly. Population analysis provided further evidence on these ideas. Thermodynamical calculation results reveal that the transition temperature of these two polymorphs of BaC2 locates near 132 K, which is consistent with the recent experimental results.

  10. Crystal structures and electronic properties of BaC2 isomers by theoretical study based on DFT

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Band structures and electronic properties of two BaC2 isomers were calculated by using density func-tional theory(DFT) properly.The ionic bond features are all typical between cation(Ba) and anion clusters(C2) in both structures of the isomers.However,a much stronger covalent bond exists in anion clusters which can be seen by inspecting the electron distribution contour that has a dull bell like shape between two carbon atoms.The shortest distance between Ba2+ and C22? and the bond length in anion clusters are different in these isomers of BaC2,which are 0.2945 nm and 0.1185 nm for the structure with the I4/mmm space group and 0.2744 and 0.1136 nm with the C2/c type,respectively.Band structures were clarified by combining the DOS to indicate the ionic bonding features more clearly.Population analysis provided further evidence on these ideas.Thermodynamical calculation results reveal that the transition temperature of these two polymorphs of BaC2 locates near 132 K,which is consistent with the recent experimental results.

  11. Towards applied theories based on computability logic

    CERN Document Server

    Japaridze, Giorgi

    2008-01-01

    Computability logic (CL) (see http://www.cis.upenn.edu/~giorgi/cl.html) is a recently launched program for redeveloping logic as a formal theory of computability, as opposed to the formal theory of truth that logic has more traditionally been. Formulas in it represent computational problems, "truth" means existence of an algorithmic solution, and proofs encode such solutions. Within the line of research devoted to finding axiomatizations for ever more expressive fragments of CL, the present paper introduces a new deductive system CL12 and proves its soundness and completeness with respect to the semantics of CL. Conservatively extending classical predicate calculus and offering considerable additional expressive and deductive power, CL12 presents a reasonable, computationally meaningful, constructive alternative to classical logic as a basis for applied theories. To obtain a model example of such theories, this paper rebuilds the traditional, classical-logic-based Peano arithmetic into a computability-logic-b...

  12. Moment matrices, border bases and radical computation

    OpenAIRE

    Mourrain, B.; J. B. Lasserre; Laurent, Monique; Rostalski, P.; Trebuchet, Philippe

    2013-01-01

    In this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is nte. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and semi-denite programming. While the border basis algorithms of [17] are ecient and numerically stable for computing complex roots, algorithms based on moment matrices [12] allow the incorporation of additional polynomials, ...

  13. 基于离散Fourier变换的通信网可靠性数据挖掘算法模型%A Data Mining Model Based on Discrete Fourier Transform(DFT)Theory for Reliability Data of Communication Networks

    Institute of Scientific and Technical Information of China (English)

    周中定; 孙青华; 梁雄健

    2003-01-01

    In this paper, it presents a data mining model based on Discrete Fourier Transform (DFT)theory for relia-bility data of communication networks, it helps us analyze aberrance data information and provide a method to analy-sis and evaluate reliability data for management of communication network. It's effective and convenient by a practicalapplication.

  14. DFT-Based Closed-form Covariance Matrix and Direct Waveforms Design for MIMO Radar to Achieve Desired Beampatterns

    KAUST Repository

    Bouchoucha, Taha

    2017-01-23

    In multiple-input multiple-out (MIMO) radar, for desired transmit beampatterns, appropriate correlated waveforms are designed. To design such waveforms, conventional MIMO radar methods use two steps. In the first step, the waveforms covariance matrix, R, is synthesized to achieve the desired beampattern. While in the second step, to realize the synthesized covariance matrix, actual waveforms are designed. Most of the existing methods use iterative algorithms to solve these constrained optimization problems. The computational complexity of these algorithms is very high, which makes them difficult to use in practice. In this paper, to achieve the desired beampattern, a low complexity discrete-Fourier-transform based closed-form covariance matrix design technique is introduced for a MIMO radar. The designed covariance matrix is then exploited to derive a novel closed-form algorithm to directly design the finite-alphabet constant-envelope waveforms for the desired beampattern. The proposed technique can be used to design waveforms for large antenna array to change the beampattern in real time. It is also shown that the number of transmitted symbols from each antenna depends on the beampattern and is less than the total number of transmit antenna elements.

  15. Spectroscopic, DFT and Z-scan supported investigation of dicyanoisophorone based push-pull NLOphoric styryl dyes

    Science.gov (United States)

    Erande, Yogesh; Sreenath, Mavila C.; Chitrambalam, Subramaniyan; Joe, Isaac H.; Sekar, Nagaiyan

    2017-04-01

    The dicyanoisophorone acceptor based NLOphores with Intramolecular Charge Transfer (ICT) character are newly synthesised, characterised and explored for linear and non linear optical (NLO) property investigation. Strong ICT character of these D-π-A styryl NLOphores is established with support of emission solvatochromism, polarity functions and Generalised Mulliken Hush (GMH) analysis. First, second and third order polarizability of these NLOphores is investigated by spectroscopic and TDDFT computational approach using CAM/B3LYP-6-311 + g (d, p) method. BLA and BOA values of these chromophores are evaluated from ground and excited state optimized geometries and found that the respective structures are approaching towards cyanine limit. Third order nonlinear susceptibility (X(3)/SUP>) along with nonlinear absorption coefficient (β) and nonlinear refraction (n2) are evaluated for these NLOphores using Z-scan experiment. All four chromophores exhibit large polarization anisotropy (Δα), first order hyperpolarizability (β0), second order hyperpolarizability (γ) and third order nonlinear susceptibility (X(3)/SUP>). TGA analysis proved these NLOphores are stable up to 320 °C and hence can be used in device fabrication.

  16. Experimental and DFT studies of solvent effects on molecular structure and physical properties of Dipyridylamine pyridine based ligand

    Science.gov (United States)

    Bilkan, Mustafa Tuğfan; Şahin, Onur; Yurdakul, Şenay

    2017-04-01

    The solvent effects on molecular structure, electronic, vibrational and thermochemical properties of 2,2‧-Dipyridylamine were investigated by using experimental and theoretical methods. 2,2‧-Dipyridylamine molecule was selected for this study intentionally because it has two pyridyl rings connected by amine bridge. This allows to change the stable equilibrium geometry, even the slightest effects. Dichloromethane was chosen as solvent. The reason for this selection is to examine whether the chlorine atoms make hydrogen bonds with the ligand atoms. For this purpose, firstly 2,2‧-Dipyridylamine solution was prepared and characterized by FT-IR and FT-Raman spectroscopy. Secondly, crystal structure of 2,2‧-Dipyridylamine was obtained to compare with the calculated geometric parameters. The crystal structure was analyzed by Single Crystal X-Ray diffraction methods. Density Functional Theory calculations were conducted with B3LYP functional and 6-31G(d) basis set. The theoretical vibrational properties of optimized geometric structure were computed in vapor and solvation phases. Two different theoretical approaches were discussed, based on the experimental results. It can be seen from the experimental and theoretical studies that the structural, vibrational, thermochemical and electronic properties are dependent on the solvent effects for selected structure. Furthermore, the chlorine atoms of Dichloromethane do not make hydrogen bonds with the ligand atoms.

  17. Redesign of the DFT/MRCI Hamiltonian.

    Science.gov (United States)

    Lyskov, Igor; Kleinschmidt, Martin; Marian, Christel M

    2016-01-21

    The combined density functional theory and multireference configuration interaction (DFT/MRCI) method of Grimme and Waletzke [J. Chem. Phys. 111, 5645 (1999)] is a well-established semi-empirical quantum chemical method for efficiently computing excited-state properties of organic molecules. As it turns out, the method fails to treat bi-chromophores owing to the strong dependence of the parameters on the excitation class. In this work, we present an alternative form of correcting the matrix elements of a MRCI Hamiltonian which is built from a Kohn-Sham set of orbitals. It is based on the idea of constructing individual energy shifts for each of the state functions of a configuration. The new parameterization is spin-invariant and incorporates less empirism compared to the original formulation. By utilizing damping techniques together with an algorithm of selecting important configurations for treating static electron correlation, the high computational efficiency has been preserved. The robustness of the original and redesigned Hamiltonians has been tested on experimentally known vertical excitation energies of organic molecules yielding similar statistics for the two parameterizations. Besides that, our new formulation is free from artificially low-lying doubly excited states, producing qualitatively correct and consistent results for excimers. The way of modifying matrix elements of the MRCI Hamiltonian presented here shall be considered as default choice when investigating photophysical processes of bi-chromophoric systems such as singlet fission or triplet-triplet upconversion.

  18. Data Cloud Computing based on LINQ

    Institute of Scientific and Technical Information of China (English)

    Junwen Lu; Yongsheng Hao; Lubin Zheng; Guanfeng Liu

    2015-01-01

    Cloud computing has demonstrated that processing very large datasets over commodity cluster can be done simply given the right programming structure. Work to date, the many choices bring difficulty because it is difficult to make a best selection. The LINQ(Language Integrated Query) programming model can be extended to massively-paralel, data-driven computations. It not only provides a seamless transition path from computing on the top transitional stores like relational databases or XML to computing on the Cloud, but also ofers an object-oriented, compositional model. In this paper, we introduce LINQ into Cloud and discuss LINQ is a good selection for Data Cloud, and then the detail of file system management was described based on LINQ.

  19. Brain emotional learning based Brain Computer Interface

    Directory of Open Access Journals (Sweden)

    Abdolreza Asadi Ghanbari

    2012-09-01

    Full Text Available A brain computer interface (BCI enables direct communication between a brain and a computer translating brain activity into computer commands using preprocessing, feature extraction and classification operations. Classification is crucial as it has a substantial effect on the BCI speed and bit rate. Recent developments of brain-computer interfaces (BCIs bring forward some challenging problems to the machine learning community, of which classification of time-varying electrophysiological signals is a crucial one. Constructing adaptive classifiers is a promising approach to deal with this problem. In this paper, we introduce adaptive classifiers for classify electroencephalogram (EEG signals. The adaptive classifier is brain emotional learning based adaptive classifier (BELBAC, which is based on emotional learning process. The main purpose of this research is to use a structural model based on the limbic system of mammalian brain, for decision making and control engineering applications. We have adopted a network model developed by Moren and Balkenius, as a computational model that mimics amygdala, orbitofrontal cortex, thalamus, sensory input cortex and generally, those parts of the brain thought responsible for processing emotions. The developed method was compared with other methods used for EEG signals classification (support vector machine (SVM and two different neural network types (MLP, PNN. The result analysis demonstrated an efficiency of the proposed approach.

  20. Infrared and vibrational CD spectra of partially solvated alpha-helices: DFT-based simulations with explicit solvent.

    Science.gov (United States)

    Turner, David R; Kubelka, Jan

    2007-02-22

    Theoretical simulations are used to investigate the effects of aqueous solvent on the vibrational spectra of model alpha-helices, which are only partly exposed to solvent to mimic alpha-helices in proteins. Infrared absorption (IR) and vibrational circular dichroism (VCD) amide I' spectra for 15-amide alanine alpha-helices are simulated using density functional theory (DFT) calculations combined with the property transfer method. The solvent is modeled by explicit water molecules hydrogen bonded to the solvated amide groups. Simulated spectra for two partially solvated model alpha-helices, one corresponding to a more exposed and the other to a more buried structure, are compared to the fully solvated and unsolvated (gas phase) simulations. The dependence of the amide I spectra on the orientation of the partially solvated helix with respect to the solvent and effects of solvation on the amide I' of 13C isotopically substituted alpha-helices are also investigated. The partial exposure to solvent causes significant broadening of the amide I' bands due to differences in the vibrational frequencies of the explicitly solvated and unsolvated amide groups. The different degree of partial solvation is reflected primarily in the frequency shifts of the unsolvated (buried) amide group vibrations. Depending on which side of the alpha-helix is exposed to solvent, the simulated IR band-shapes exhibit significant changes, from broad and relatively featureless to distinctly split into two maxima. The simulated amide I' VCD band-shapes for the partially solvated alpha-helices parallel the broadening of the IR and exhibit more sign variation, but generally preserve the sign pattern characteristic of the alpha-helical structures and are much less dependent on the alpha-helix orientation with respect to the solvent. The simulated amide I' IR spectra for the model peptides with explicitly hydrogen-bonded water are consistent with the experimental data for small alpha-helical proteins

  1. DFT/TDDFT investigation of the modulation of photochromic properties in an organoboron-based diarylethene by fluoride ions.

    Science.gov (United States)

    Liu, Shujuan; Sun, Shi; Wang, Chuanming; Zhao, Qiang; Sun, Huibin; Li, Fuyou; Fan, Quli; Huang, Wei

    2011-02-07

    The diarylethene derivative 1,2-bis-(5'-dimesitylboryl-2'-methylthieny-3'-yl)-cyclopentene (1) containing dimesitylboryl groups is an interesting photochromic material. The dimesitylboryl groups can bind to F(-), which tunes the optical and electronic properties of the diarylethene compound. Hence, the diarylethene derivative 1 containing dimesitylboryl groups is sensitive to both light and F(-), and its photochromic properties can be tuned by a fluoride ion. Herein, we studied the substituent effect of dimesitylboron groups on the optical properties of both the closed-ring and open-ring isomers of the diarylethene molecule by DFT/TDDFT calculations and found that these methods are reliable for the determination of the lowest singlet excitation energies of diarylethene compounds. The introduction of dimesitylboron groups to the diarylethene compound can elongate its conjugation length and change the excited-state properties from π→π* transition to a charge-transfer state. This explains the modulation of photochromic properties through the introduction of dimesitylboron groups. Furthermore, the photochromic properties can be tuned through the binding of F(-) to a boron center and the excited state of the diarylethene compound is changed from a charge-transfer state to a π→π* transition. Hence, a subtle control of the photochromic spectroscopic properties was realized. In addition, the changes of electronic characteristics by the isomerization reaction of diarylethene compounds were also investigated with theoretical calculations. For the model compound 2 without dimesitylboryl groups, the closed-ring isomer has better hole- and electron-injection abilities, as well as higher charge-transport rates, than the open-ring isomer. The introduction of dimesitylboron groups to diarylethene can dramatically improve the charge-injection and -transport abilities. The closed isomer of compound 1 (1 C) has the best hole- and electron-injection abilities, whereas the

  2. The DFT study on the reaction between benzaldehyde and 4-amine-4H-1,2,4-triazole and their derivatives as a source of stable hemiaminals and Schiff bases. Effect of substitution and solvation on the reaction mechanism.

    Science.gov (United States)

    Berski, Slawomir; Gordon, Agnieszka J; Ciunik, Leszek Zbigniew

    2015-03-01

    Reaction mechanism for the benzaldehyde (ald) and 4-amine-4H-1,2,4-triazole (4at) has been investigated at the DFT (B3LYP)/6-31+G(d) computational level. Three transition states (TS) have been identified. The TS1 corresponds to hydrogen transfer from the NH2 group to the C = O bond and nucleophillic attack of the carbon atom from the aldehyde group on the nitrogen atom from the NH2 group in 4at. The result of this reaction is the hemiaminal molecule. The TS2 characterises an internal rearrangement of the benzene and triazole rings in the hemiaminal molecule. The TS3 leads to breaking of the O-H bond, the elimination reaction of the H2O molecule, and formation of the C=N bond. The final product of this reaction is a Schiff base. In order to determine the most favorable conditions for hemiaminal formation, the influence of electronic structure modification on the energetic properties during the reaction of benzaldehyde and 4-amine-4H-1,2,4-triazole has been studied. Thirteen substituents: NH2, OH, OCH3, CH3, F, I, Cl, Br, COH, COOH, CF3, CN, NO2, with different Hammett's constant values (σ = -0.66-+0.78) have been considered. Finally, the reaction mechanism has been investigated in the presence of 1 to 5 water molecules.

  3. Understanding Computer-Based Digital Video.

    Science.gov (United States)

    Martindale, Trey

    2002-01-01

    Discussion of new educational media and technology focuses on producing and delivering computer-based digital video. Highlights include video standards, including international standards and aspect ratio; camera formats and features, including costs; shooting digital video; editing software; compression; and a list of informative Web sites. (LRW)

  4. Agent based computational model of trust

    NARCIS (Netherlands)

    A. Gorobets (Alexander); B. Nooteboom (Bart)

    2004-01-01

    textabstractThis paper employs the methodology of Agent-Based Computational Economics (ACE) to investigate under what conditions trust can be viable in markets. The emergence and breakdown of trust is modeled in a context of multiple buyers and suppliers. Agents adapt their trust in a partner, the w

  5. Single electron tunneling based arithmetic computation

    NARCIS (Netherlands)

    Lageweg, C.R.

    2004-01-01

    In this dissertation we investigate the implementation of computer arithmetic operations with Single Electron Tunneling (SET) technology based circuits. In our research we focus on the effective utilization of the SET technologys specific characteristic, i.e., the ability to control the transport of

  6. Educator Beliefs Regarding Computer-Based Instruction.

    Science.gov (United States)

    Swann, D. LaDon; Branson, Floyd, Jr.; Talbert, B. Allen

    2003-01-01

    Extension educators (n=17) completed two of five technical sections from an aquaculture CD-ROM tutorial. Evidence from pre/post-training questionnaires, content assessments, and follow-up interviews reveals favorable attitudes toward computer-based inservice training. The ability to spend less time out of their county and to review materials after…

  7. Evaluation of a Computer-Based Narrative

    Science.gov (United States)

    Sharf, Richard S.

    1978-01-01

    A computer-based narrative report integrating results from the Strong Vocational Interest Blank, the Opinion Attitude and Interest Survey, and the Cooperative English Test was compared with a standard profile format. No differences were found between the two methods for male and female. (Author)

  8. Noise Tracking Using DFT Domain Subspace Decompositions

    NARCIS (Netherlands)

    Hendriks, R.C.; Jensen, J.; Heusdens, R.

    2008-01-01

    All discrete Fourier transform (DFT) domain-based speech enhancement gain functions rely on knowledge of the noise power spectral density (PSD). Since the noise PSD is unknown in advance, estimation from the noisy speech signal is necessary. An overestimation of the noise PSD will lead to a loss in

  9. Noise Tracking Using DFT Domain Subspace Decompositions

    NARCIS (Netherlands)

    Hendriks, R.C.; Jensen, J.; Heusdens, R.

    2008-01-01

    All discrete Fourier transform (DFT) domain-based speech enhancement gain functions rely on knowledge of the noise power spectral density (PSD). Since the noise PSD is unknown in advance, estimation from the noisy speech signal is necessary. An overestimation of the noise PSD will lead to a loss in

  10. A potential role of substrate as a base for deprotonation pathway in Rh-catalysed C-H amination of heteroArenes: DFT insights

    KAUST Repository

    Ajitha, Manjaly John

    2016-03-29

    The possibility of direct introduction of a new functionality through C–H bond activation is an attractive strategy in covalent synthesis. Here, we investigated the mechanism of Rh-catalysed C-H amination of the hetero-aryl substrate (2-phenylpyridine) using phenyl azide as nitrogen source by density functional theory (DFT). For the deprotocyclometallation and protodecyclometallation processes of the title reaction, we propose a stepwise base-assisted mechanism (pathway I) instead of previously reported concerted mechanism (pathway II). In the new mechanism proposed here, 2-phenylpyridine acts as a base in the initial deprotonation step (C-H bond cleavage) and transports the proton towards the final protonation step. In fact, the N-H bond of the strong conjugate acid (formed during initial C-H bond cleavage) considered in pathway I (via TS4) is more acidic than the C-H bond of the neutral substrate considered in pathway II (via TS5). The higher activation barrier of TS5 mainly originates from the ring strain of the four membered cyclic transition state. The vital role of base, as disclosed here, can potentially have broader mechanistic implications for the development of reaction conditions of transition metal catalysed reactions.

  11. Performance and stability of low-cost dye-sensitized solar cell based crude and pre-concentrated anthocyanins: Combined experimental and DFT/TDDFT study

    Science.gov (United States)

    Chaiamornnugool, Phrompak; Tontapha, Sarawut; Phatchana, Ratchanee; Ratchapolthavisin, Nattawat; Kanokmedhakul, Somdej; Sang-aroon, Wichien; Amornkitbamrung, Vittaya

    2017-01-01

    The low cost DSSCs utilized by crude and pre-concentrated anthocyanins extracted from six anthocyanin-rich samples including mangosteen pericarp, roselle, red cabbage, Thai berry, black rice and blue pea were fabricated. Their photo-to-current conversion efficiencies and stability were examined. Pre-concentrated extracts were obtained by solid phase extraction (SPE) using C18 cartridge. The results obviously showed that all pre-concentrated extracts performed on photovoltaic performances in DSSCs better than crude extracts except for mangosteen pericarp. The DSSC sensitized by pre-concentrated anthocyanin from roselle and red cabbage showed maximum current efficiency η = 0.71% while DSSC sensitized by crude anthocyanin from mangosteen pericarp reached maximum efficiency η = 0.97%. In addition, pre-concentrated extract based cells possess more stability than those of crude extract based cells. This indicates that pre-concentration of anthocyanin via SPE method is very effective for DSSCs based on good photovoltaic performance and stability. The DFT/TDDFT calculations of electronic and photoelectrochemical properties of the major anthocyanins found in the samples are employed to support the experimental results.

  12. A Comparison of the Performance of the Semiempirical PM6 Method Versus DFT Methods in Ru-Catalyzed Olefin Metathesis

    Science.gov (United States)

    Correa, Andrea; Poater, Albert; Ragone, Francesco; Cavallo, Luigi

    In this work we compare the performance of the semiempirical PM6 method with a more accurate DFT method when applied to Ru-catalyzed olefin metathesis. We demonstrate that the PM6 method reproduces with interesting accuracy the geometries located with a DFT approach. As for the energetics, the relative DFT stability of the metallacycle with respect to the coordination intermediate is reproduced with reasonable accuracy by the PM6 method, whereas the olefin coordination energy and the energy barrier of the metathesis step are overestimated. Further, for the same system we performed a PM6-based meta-dynamics study of the olefin metathesis reaction, which indicated a reasonable good behavior of the system also under dynamic conditions. In conclusion, the obtained results validate the use of the semiempirical PM6 method for preliminary and computationally fast screening on new ligands/substrates in Ru catalyzed olefin metathesis.

  13. WEB BASED LEARNING OF COMPUTER NETWORK COURSE

    Directory of Open Access Journals (Sweden)

    Hakan KAPTAN

    2004-04-01

    Full Text Available As a result of developing on Internet and computer fields, web based education becomes one of the area that many improving and research studies are done. In this study, web based education materials have been explained for multimedia animation and simulation aided Computer Networks course in Technical Education Faculties. Course content is formed by use of university course books, web based education materials and technology web pages of companies. Course content is formed by texts, pictures and figures to increase motivation of students and facilities of learning some topics are supported by animations. Furthermore to help working principles of routing algorithms and congestion control algorithms simulators are constructed in order to interactive learning

  14. Effect of the components' interface on the synthesis of methanol over Cu/ZnO from CO2/H2: a microkinetic analysis based on DFT + U calculations.

    Science.gov (United States)

    Tang, Qian-Lin; Zou, Wen-Tian; Huang, Run-Kun; Wang, Qi; Duan, Xiao-Xuan

    2015-03-21

    The elucidation of chemical reactions occurring on composite systems (e.g., copper (Cu)/zincite (ZnO)) from first principles is a challenging task because of their very large sizes and complicated equilibrium geometries. By combining the density functional theory plus U (DFT + U) method with microkinetic modeling, the present study has investigated the role of the phase boundary in CO2 hydrogenation to methanol over Cu/ZnO. The absence of hydrogenation locations created by the interface between the two catalyst components was revealed based on the calculated turnover frequency under realistic conditions, in which the importance of interfacial copper to provide spillover hydrogen for remote Cu(111) sites was stressed. Coupled with the fact that methanol production on the binary catalyst was recently believed to predominantly involve the bulk metallic surface, the spillover of interface hydrogen atoms onto Cu(111) facets facilitates the production process. The cooperative influence of the two different kinds of copper sites can be rationalized applying the Brönsted-Evans-Polanyi (BEP) relationship and allows us to find that the catalytic activity of ZnO-supported Cu catalysts is of volcano type with decrease in the particle size. Our results here may have useful implications in the future design of new Cu/ZnO-based materials for CO2 transformation to methanol.

  15. TD-DFT study on the excited-state proton transfer in the fluoride sensing of a turn-off type fluorescent chemosensor based on anthracene derivatives.

    Science.gov (United States)

    Song, Ping; Ding, Jun-Xia; Chu, Tian-Shu

    2012-11-01

    The sensing mechanism for fluoride chemosensor based on anthracene structure has been investigated by DFT and TDDFT methods. The results show that the similar geometries in S(0) and S(1) states in the absence of the fluoride anion induce the local excited (LE) state over the anthracene moiety, which is responsible for the strong fluorescence. The fluorescence quenching phenomenon for F-coordinated complex can be explained by the photoinduced electron transfer (PET) process from benzylic amide to anthracene moiety. Moreover, the strong electronegativity for fluoride anion in the F-complex constructs the intermolecular hydrogen bond of N-H…F in the ground state. In contrast, the upper proton in the urea group close to phenyl group prefers to bind fluoride anion in S(1) state of the F-complex, and it presents excited-state proton transfer (ESPT) to form another hydrogen bond like N…H-F, which has been confirmed by natural bond orbital (NBO) analysis and the potential energy curve of S(1) state for the function of N-H bond. In this novel and efficient fluoride fluorescent chemosensor based on anthracene, the anthracene moiety is regarded as not only the fluorescent source, but the template for introducing the binding sites for fluoride anion.

  16. The acid-base and redox reactivity of CeO2 nanoparticles: Influence of the Hubbard U term in DFT + U studies

    Science.gov (United States)

    Boronat, Mercedes; López-Ausens, Tirso; Corma, Avelino

    2016-06-01

    The interaction of small molecules with acid-base and redox centers in small Ce21O42 nanoparticles has been theoretically investigated using the DFT + U approach with the PW91 functional and U = 0.2 and 4 eV, in order to determine the influence of the U value on the trends observed in selected properties describing such interactions. CO adsorption at low coordinated Ce4 + Lewis acid centers, water adsorption and dissociation at acid-base pairs, formation of oxygen vacancy defects by removal of an oxygen atom from the system, and interaction of molecular O2 with such defects have been considered. The largest effect of the value of U is found for the description of the reduced Ce21O41 nanoparticle. In all other cases involving stoichiometric and oxidized Ce21O42 and Ce21O43 systems, the trends in the calculated adsorption and reaction energies, optimized geometries, charge distribution, and vibrational frequencies are quite similar at the three levels considered.

  17. Polymorphism and disorder in natural active ingredients. Low and high-temperature phases of anhydrous caffeine: Spectroscopic ((1)H-(14)N NMR-NQR/(14)N NQR) and solid-state computational modelling (DFT/QTAIM/RDS) study.

    Science.gov (United States)

    Seliger, Janez; Žagar, Veselko; Apih, Tomaž; Gregorovič, Alan; Latosińska, Magdalena; Olejniczak, Grzegorz Andrzej; Latosińska, Jolanta Natalia

    2016-03-31

    The polymorphism of anhydrous caffeine (1,3,7-trimethylxanthine; 1,3,7-trimethyl-1H-purine-2,6-(3H,7H)-dione) has been studied by (1)H-(14)N NMR-NQR (Nuclear Magnetic Resonance-Nuclear Quadrupole Resonance) double resonance and pure (14)N NQR (Nuclear Quadrupole Resonance) followed by computational modelling (Density Functional Theory, supplemented Quantum Theory of Atoms in Molecules with Reduced Density Gradient) in solid state. For two stable (phase II, form β) and metastable (phase I, form α) polymorphs the complete NQR spectra consisting of 12 lines were recorded. The assignment of signals detected in experiment to particular nitrogen sites was verified with the help of DFT. The shifts of the NQR frequencies, quadrupole coupling constants and asymmetry parameters at each nitrogen site due to polymorphic transition were evaluated. The strongest shifts were observed at N(3) site, while the smallest at N(9) site. The commercial pharmaceutical sample was found to contain approximately 20-25% of phase I and 75-80% of phase II. The orientational disorder in phase II with a local molecular arrangement mimics that in phase I. Substantial differences in the intermolecular interaction phases I and II of caffeine were analysed using computational (DFT/QTAIM/RDS) approach. The analysis of local environment of each nitrogen nucleus permitted drawing some conclusions on the topology of interactions in both polymorphs. For the most stable orientations in phase I and phase II the maps of the principal component qz of EFG tensor and its asymmetry parameter at each point of the molecular system were calculated and visualized. The relevant maps calculated for both phases I and II indicates small variation in electrostatic potential upon phase change. Small differences between packings in phases slightly disturb the neighbourhood of the N(1) and N(7) nitrogens, thus are meaningless from the biological point of view. The composition of two phases in pharmaceutical material

  18. A Comparative Evaluation of Computer Based and Non-Computer Based Instructional Strategies.

    Science.gov (United States)

    Emerson, Ian

    1988-01-01

    Compares the computer assisted instruction (CAI) tutorial with its non-computerized pedagogical roots: the Socratic Dialog with Skinner's Programmed Instruction. Tests the effectiveness of a CAI tutorial on diffusion and osmosis against four other interactive and non-interactive instructional strategies. Notes computer based strategies were…

  19. Computer-based and web-based radiation safety training

    Energy Technology Data Exchange (ETDEWEB)

    Owen, C., LLNL

    1998-03-01

    The traditional approach to delivering radiation safety training has been to provide a stand-up lecture of the topic, with the possible aid of video, and to repeat the same material periodically. New approaches to meeting training requirements are needed to address the advent of flexible work hours and telecommuting, and to better accommodate individuals learning at their own pace. Computer- based and web-based radiation safety training can provide this alternative. Computer-based and web- based training is an interactive form of learning that the student controls, resulting in enhanced and focused learning at a time most often chosen by the student.

  20. Benchmarks for electronically excited states: Time-dependent density functional theory and density functional theory based multireference configuration interaction

    DEFF Research Database (Denmark)

    Silva-Junior, Mario R.; Schreiber, Marko; Sauer, Stephan P. A.;

    2008-01-01

    Time-dependent density functional theory (TD-DFT) and DFT-based multireference configuration interaction (DFT/MRCI) calculations are reported for a recently proposed benchmark set of 28 medium-sized organic molecules. Vertical excitation energies, oscillator strengths, and excited-state dipole...... moments are computed using the same geometries (MP2/6-31G*) and basis set (TZVP) as in our previous ab initio benchmark study on electronically excited states. The results from TD-DFT (with the functionals BP86, B3LYP, and BHLYP) and from DFT/MRCI are compared against the previous high-level ab initio...

  1. Novel iridium(III) complexes based on 2-(2,2’-bithien-5-yl)-quinoline. Synthesis, photophysical, photochemical and DFT studies

    Energy Technology Data Exchange (ETDEWEB)

    Szafraniec-Gorol, Grażyna, E-mail: grazyna.szafraniec@wp.pl [Institute of Chemistry, Faculty of Mathematics, Physics and Chemistry, University of Silesia, Szkolna 9, 40-007 Katowice (Poland); Słodek, Aneta; Filapek, Michał [Institute of Chemistry, Faculty of Mathematics, Physics and Chemistry, University of Silesia, Szkolna 9, 40-007 Katowice (Poland); Boharewicz, Bartosz; Iwan, Agnieszka [Electrotechnical Institute, Division of Electrotechnology and Materials Science, M. Sklodowskiej-Curie 55/61, 50-369 Wroclaw (Poland); Jaworska, Maria; Żur, Lidia; Sołtys, Marta; Pisarska, Joanna; Grudzka-Flak, Iwona [Institute of Chemistry, Faculty of Mathematics, Physics and Chemistry, University of Silesia, Szkolna 9, 40-007 Katowice (Poland); Czajkowska, Sylwia [Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Sklodowskiej 34, 41-819 Zabrze (Poland); Sojka, Maciej; Danikiewicz, Witold [Institute of Organic Chemistry, Polish Academy of Science, Kasprzaka 44/52, 01-224 Warsaw (Poland); Krompiec, Stanisław [Institute of Chemistry, Faculty of Mathematics, Physics and Chemistry, University of Silesia, Szkolna 9, 40-007 Katowice (Poland)

    2015-07-15

    Four novel cyclometalated iridium(III) complexes: [Ir(q-bt-Ph){sub 2}(phen)]PF{sub 6}, [Ir(q-bt-Ph){sub 2}(acac)], [Ir(q-bt-Me){sub 2}(bpy)]PF{sub 6} and [Ir(q-bt-Me){sub 2}(acac)] (where q-bt-Ph, q-bt-Me correspond to 2-(2,2’-bithien-5-yl)-4-phenylquinoline and 2-(2,2’-bithien-5-yl)-4-methylquinoline), are reported. The complexes were characterized by NMR, FTIR and HRMS. The optical, electrochemical properties and thermal stability of novel iridium(III) complexes were thoroughly investigated. The complexes emit a light in the narrow range of 693–707 nm. The optical study showed that replacement of fragment in the main quinoline ligand did not affect wavelength of the emitted light. On the other hand, the modification of the ancillary ligand and substituent in the quinoline ring caused the increase of the photoluminescence quantum yields. Electrochemical experiments demonstrate that the oxidation process for complexes [Ir(q-bt-Ph){sub 2}(phen)]PF{sub 6} and [Ir(q-bt-Ph){sub 2}(acac)] was reversible (or quasi-reversible) and well detectable whereas for complexes with quinoline substituted by methyl group was irreversible, even at low temperature (−70 °C). The electrochemical and photophysical studies have been well confirmed by density functional theory (DFT) calculations. In addition, bulk heterojunction polymer solar cells based on complexes [Ir(q-bt-Ph){sub 2}(phen)]PF{sub 6} and [Ir(q-bt-Ph){sub 2}(acac)] were fabricated. Only the solar cell incorporating [Ir(q-bt-Ph){sub 2}(acac)] exhibited a photovoltaic effect. The architecture of the cell was ITO/PEDOT:PSS/P3HT:PCBM:[Ir(q-bt-Ph){sub 2}(acac)]/Al. A power conversion efficiency of 0.25% was measured under 1 sun illumination using an AM 1.5G filter to simulate the solar spectrum. - Graphical abstract: Display Omitted - Highlights: • Iridium(III) complexes bearing 2-bithienylquinolines as main ligands were examined. • Optical and electrochemical measurements were compared with DFT calculations.

  2. Stereochemical and conformational study on fenoterol by ECD spectroscopy and TD-DFT calculations.

    Science.gov (United States)

    Tedesco, Daniele; Zanasi, Riccardo; Wainer, Irving W; Bertucci, Carlo

    2014-03-01

    Fenoterol and its derivatives are selective β2-adrenergic receptor (β2-AR) agonists whose stereoselective biological activities have been extensively investigated in the past decade; a complete stereochemical characterization of fenoterol derivatives is therefore crucial for a better understanding of the effects of stereochemistry on β2-AR binding. In the present project, the relationship between chiroptical properties and absolute stereochemistry of the stereoisomers of fenoterol (1) was investigated by experimental ECD spectroscopy and time-dependent density functional theory (TD-DFT). DFT geometry optimizations were carried out at the RI-B97D/TZVP/IEFPCM(MeOH) level and subsequent TD-DFT calculations were performed using the PBE0 hybrid functional. Despite the large pool of equilibrium conformers found for the investigated compounds and the known limitations of the level of theory employed, the computational protocol was able to reproduce the experimental ECD spectra of the stereoisomers of 1. The main contribution to the overall chiroptical properties was found to arise from the absolute configuration of the chiral center in α-position to the resorcinol moiety. Based on this evidence, a thorough conformational analysis was performed on the optimized DFT conformers, which revealed the occurrence of a different equilibrium between conformational patterns for the diastereomers of fenoterol: the (R,R')/(S,S') enantiomeric pair showed a higher population of folded conformations than the (R,S')/(S,R') pair.

  3. Critical analysis of fragment-orbital DFT schemes for the calculation of electronic coupling values.

    Science.gov (United States)

    Schober, Christoph; Reuter, Karsten; Oberhofer, Harald

    2016-02-07

    We present a critical analysis of the popular fragment-orbital density-functional theory (FO-DFT) scheme for the calculation of electronic coupling values. We discuss the characteristics of different possible formulations or "flavors" of the scheme which differ by the number of electrons in the calculation of the fragments and the construction of the Hamiltonian. In addition to two previously described variants based on neutral fragments, we present a third version taking a different route to the approximate diabatic state by explicitly considering charged fragments. In applying these FO-DFT flavors to the two molecular test sets HAB7 (electron transfer) and HAB11 (hole transfer), we find that our new scheme gives improved electronic couplings for HAB7 (-6.2% decrease in mean relative signed error) and greatly improved electronic couplings for HAB11 (-15.3% decrease in mean relative signed error). A systematic investigation of the influence of exact exchange on the electronic coupling values shows that the use of hybrid functionals in FO-DFT calculations improves the electronic couplings, giving values close to or even better than more sophisticated constrained DFT calculations. Comparing the accuracy and computational cost of each variant, we devise simple rules to choose the best possible flavor depending on the task. For accuracy, our new scheme with charged-fragment calculations performs best, while numerically more efficient at reasonable accuracy is the variant with neutral fragments.

  4. Critical analysis of fragment-orbital DFT schemes for the calculation of electronic coupling values

    Energy Technology Data Exchange (ETDEWEB)

    Schober, Christoph; Reuter, Karsten; Oberhofer, Harald, E-mail: harald.oberhofer@ch.tum.de [Chair for Theoretical Chemistry, Technische Universität München, Lichtenbergstr. 4, D-85747 Garching (Germany)

    2016-02-07

    We present a critical analysis of the popular fragment-orbital density-functional theory (FO-DFT) scheme for the calculation of electronic coupling values. We discuss the characteristics of different possible formulations or “flavors” of the scheme which differ by the number of electrons in the calculation of the fragments and the construction of the Hamiltonian. In addition to two previously described variants based on neutral fragments, we present a third version taking a different route to the approximate diabatic state by explicitly considering charged fragments. In applying these FO-DFT flavors to the two molecular test sets HAB7 (electron transfer) and HAB11 (hole transfer), we find that our new scheme gives improved electronic couplings for HAB7 (−6.2% decrease in mean relative signed error) and greatly improved electronic couplings for HAB11 (−15.3% decrease in mean relative signed error). A systematic investigation of the influence of exact exchange on the electronic coupling values shows that the use of hybrid functionals in FO-DFT calculations improves the electronic couplings, giving values close to or even better than more sophisticated constrained DFT calculations. Comparing the accuracy and computational cost of each variant, we devise simple rules to choose the best possible flavor depending on the task. For accuracy, our new scheme with charged-fragment calculations performs best, while numerically more efficient at reasonable accuracy is the variant with neutral fragments.

  5. Computing negentropy based signatures for texture recognition

    Directory of Open Access Journals (Sweden)

    Daniela COLTUC

    2007-12-01

    Full Text Available The proposed method aims to provide a new tool for texture recognition. For this purpose, a set of texture samples are decomposed by using the FastICA algorithm and characterized by a negentropy based signature. In order to do recognition, the texture signatures are compared by means of Minkowski distance. The recognition rates, computed for a set of 320 texture samples, show a medium recognition accuracy and the method may be further improved.

  6. Application of spectroscopic methods for identification (FT-IR, Raman spectroscopy) and determination (UV, EPR) of quercetin-3-O-rutinoside. Experimental and DFT based approach.

    Science.gov (United States)

    Paczkowska, Magdalena; Lewandowska, Kornelia; Bednarski, Waldemar; Mizera, Mikołaj; Podborska, Agnieszka; Krause, Anna; Cielecka-Piontek, Judyta

    2015-04-05

    Vibrational (FT-IR, Raman) and electronic (UV, EPR) spectral measurements were performed for an analysis of rutin (quercetin-3-O-rutinoside) obtained from Rutaofficinalis. The identification of rutin was done with the use of FT-IR and Raman spectra. Those experimental spectra were determined with the support of theoretical calculations based on a DFT method with the B3LYP hybrid functional and 6-31G(d,p) basis set. The application of UV and EPR spectra was found to be a suitable analytical approach to the evaluation of changes in rutin exposed to certain physicochemical factors. Differences in absorbance observed in direct UV spectra were used to monitor changes in the concentration of rutin in degraded samples. Spectra of electron paramagnetic resonance allowed studying the process of free-radical quenching in rutin following its exposure to light. The molecular electrostatic potential (MEP) and frontier molecular orbitals (LUMO-HOMO) were also determined in order to predict structural changes and reactive sites in rutin.

  7. A novel copper (II) complex containing a tetradentate Schiff base: Synthesis, spectroscopy, crystal structure, DFT study, biological activity and preparation of its nano-sized metal oxide

    Science.gov (United States)

    Tohidiyan, Zeinab; Sheikhshoaie, Iran; Khaleghi, Mouj; Mague, Joel T.

    2017-04-01

    A new nano-sized copper (II) complex, [Cu(L)] with a tetra dentate Schiff base ligand, 2-((E)-(2-(E-5- bromo-2-hydroxybezenylideneamino) methyl)-4-bromophenol [H2L] was prepared by the reaction between of Cu (CH3COO)2·2H2O and (H2L) ligand with the ratio of 1:1, at the present of triethylamine by sonochemical method. The structure of [Cu (L)] complex was determined by FT-IR, UV-Vis, FESEM and molar conductivity. The structure of [Cu (L)] complex was characterized by single crystal X-ray diffraction. The geometry of [Cu (L)] complex was optimized using density functional theory (DFT) method with the B3LYP/6-31(d) level of theory. The calculated bond lengths and bond angles are in good agreement with the X-ray data. This complex was used as a novel precursor for preparing of CuO nano particles by the thermal decomposition method. The antibacterial activities of [H2L] ligand, nano-sized [Cu (L)] complex and nano-sized CuO have been screened against various strains of bacteria. According to the results, nano-sized CuO can be considered as an appropriate antibiotic agent.

  8. Crystal structures, DFT calculations and Hirshfeld surface analyses of three new cobalt(III) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine

    Science.gov (United States)

    Masoudi, Mohaddeseh; Behzad, Mahdi; Arab, Ali; Tarahhomi, Atekeh; Rudbari, Hadi Amiri; Bruno, Giuseppe

    2016-10-01

    Three new Cobalt(III) Schiff base complexes were synthesized and characterized by spectroscopic methods and x-ray crystallography. The DFT optimized structures of the complexes agreed well with the corresponding x-ray structures. According to the calculated vibrational normal modes, the observed signals in the IR spectra of the complexes were assigned. The experimental UV-Vis spectra of the complexes were also discussed considering the calculated excited states and molecular orbitals. Hirshfeld surface analysis was carried out to study the inter-contact interactions in these complexes. These studies provided comprehensive description of such inter-contact interactions by means of an appealing graphical approach using 3D Hirshfeld surfaces and 2D fingerprint plots derived from the surfaces. It indicated the dominant role of various hydrogen intermolecular interactions such as H⋯H (above 60%), C⋯H/H⋯C (near 15%-20%), O⋯H/H⋯O (about 16% or 17% for structures with counter ion ClO4-) and H⋯F (17% for structure with counter ion PF6-) contacts into the crystal packing which are discussed in details.

  9. Application of spectroscopic methods for identification (FT-IR, Raman spectroscopy) and determination (UV, EPR) of quercetin-3-O-rutinoside. Experimental and DFT based approach

    Science.gov (United States)

    Paczkowska, Magdalena; Lewandowska, Kornelia; Bednarski, Waldemar; Mizera, Mikołaj; Podborska, Agnieszka; Krause, Anna; Cielecka-Piontek, Judyta

    2015-04-01

    Vibrational (FT-IR, Raman) and electronic (UV, EPR) spectral measurements were performed for an analysis of rutin (quercetin-3-O-rutinoside) obtained from Rutaofficinalis. The identification of rutin was done with the use of FT-IR and Raman spectra. Those experimental spectra were determined with the support of theoretical calculations based on a DFT method with the B3LYP hybrid functional and 6-31G(d,p) basis set. The application of UV and EPR spectra was found to be a suitable analytical approach to the evaluation of changes in rutin exposed to certain physicochemical factors. Differences in absorbance observed in direct UV spectra were used to monitor changes in the concentration of rutin in degraded samples. Spectra of electron paramagnetic resonance allowed studying the process of free-radical quenching in rutin following its exposure to light. The molecular electrostatic potential (MEP) and frontier molecular orbitals (LUMO-HOMO) were also determined in order to predict structural changes and reactive sites in rutin.

  10. Montecrinanes A-C: Triterpenes with an Unprecedented Rearranged Tetracyclic Skeleton from Celastrus vulcanicola. Insights into Triterpenoid Biosynthesis Based on DFT Calculations.

    Science.gov (United States)

    Purino, Martín; Ardiles, Alejandro E; Callies, Oliver; Jiménez, Ignacio A; Bazzocchi, Isabel L

    2016-05-23

    Three new triterpenoids with an unprecedented 6/6/6/6-fused tetracyclic carbon skeleton, montecrinanes A-C (1-3), were isolated from the root bark of Celastrus vulcanicola, along with known D:B-friedobaccharanes (4-6), and lupane-type triterpenes (7-12). The stereostructures of the new metabolites were elucidated based on spectroscopic (1D and 2D NMR) and spectrometric (HR-EIMS and HR-ESIMS) techniques. Their absolute configurations were determined by both NMR spectroscopy, with (R)-(-)-α-methoxyphenylacetic acid as a chiral derivatizing agent, and biogenetic considerations. Biogenetic pathways for montecrinane and D:B-friedobaccharane skeletons were proposed and studied by DFT methods. The theoretical results support the energetic feasibility of the putative biogenetic pathways, in which the 1,2-methyl shift from the secondary baccharenyl cation represents a novel and key reaction step for a new montecrinane skeleton. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Synthesis, growth, optical and DFT calculation of 2-naphthol derived Mannich base organic non linear optical single crystal for frequency conversion applications

    Science.gov (United States)

    Raj, A. Dennis; Jeeva, M.; Shankar, M.; Purusothaman, R.; Prabhu, G. Venkatesa; Potheher, I. Vetha

    2016-11-01

    2-naphthol derived Mannich base 1-((4-methylpiperazin-1-yl) (phenyl) methyl) naphthalen-2-ol (MPN) - a nonlinear optical single crystal was synthesized and successfully grown by slow evaporation technique at room temperature. The molecular structure was confirmed by single crystal XRD, FT-IR, 1H NMR and 13C NMR spectral studies. The single crystal X-ray diffraction analysis reveals that the crystal belongs to orthorhombic crystal system with non-centrosymmetric space group Pna21. The chemical shift of 5.34 ppm (singlet methine CH proton) in 1H NMR and signal for the CH carbon around δ70.169 ppm in 13C NMR confirms the formation of the title compound. The crystal growth pattern and dislocations of crystal are analyzed using chemical etching technique. UV cut off wavelength of the material was found to be 212 nm. The second harmonic generation (SHG) of MPN was determined from Kurtz Perry powder technique and the efficiency is almost equal to that of standard KDP crystal. The laser damage threshold was measured by passing Nd: YAG laser beam through the sample and it was found to be 1.1974 GW/cm2. The material was thermally stable up to 142 °C. The relationship between the molecular structure and the optical properties was also studied from quantum chemical calculations using Density Functional Theory (DFT) and reported for the first time.

  12. A polyhedral approach to computing border bases

    CERN Document Server

    Braun, Gábor

    2009-01-01

    Border bases can be considered to be the natural extension of Gr\\"obner bases that have several advantages. Unfortunately, to date the classical border basis algorithm relies on (degree-compatible) term orderings and implicitly on reduced Gr\\"obner bases. We adapt the classical border basis algorithm to allow for calculating border bases for arbitrary degree-compatible order ideals, which is \\emph{independent} from term orderings. Moreover, the algorithm also supports calculating degree-compatible order ideals with \\emph{preference} on contained elements, even though finding a preferred order ideal is NP-hard. Effectively we retain degree-compatibility only to successively extend our computation degree-by-degree. The adaptation is based on our polyhedral characterization: order ideals that support a border basis correspond one-to-one to integral points of the order ideal polytope. This establishes a crucial connection between the ideal and the combinatorial structure of the associated factor spaces.

  13. 基于滑动DFT和插值DFT算法的GPS信号载波跟踪方法%Carrier Tracking Method of GPS Signals Based on Sliding DFT and Interpolated DFT Algorithms

    Institute of Scientific and Technical Information of China (English)

    李春宇; 张晓林; 杨昕欣

    2008-01-01

    在分析GPS接收机跟踪环路信号特征的基础上,将滑动离散傅里叶变换(DFT)算法和插值DFT频率估计算法相结合,提出一种在频域进行的载波跟踪方法.该方法首先根据捕获时得到的粗略载波频率估计值确定计算DFT值点的范围,然后利用滑动DFT算法计算这部分点的DFT值,最后利用插值DFT频率估计算法估计载波频率,进行跟踪环路中载波频率的更新.该方法计算复杂度低,便于实际应用.仿真结果显示,该方法能够对载波频率正确跟踪,验证了算法的可行性.

  14. DFT study on the impact of the methylaluminoxane cocatalyst in ethylene oligomerization using a titanium-based catalyst

    KAUST Repository

    Pasha, Farhan Ahmad

    2015-01-26

    A computational study within the framework of density functional theory is presented on the oligomerization of ethylene to yield 1-hexene using [(η5-C5H4CMe2C6H5)]TiCl3/MAO] catalyst. This study explicitly takes into account a methylaluminoxane (MAO) cocatalyst model, where the MAO cluster has become an anionic species after having abstracted one chloride anion, yielding a cationic activated catalyst. Hence, the reaction profile was calculated using the zwitterionic system, and the potential energy surface has been compared to the cationic catalytic system. Modest differences were found between the two free energy profiles. However, we show for the first time that the use of a realistic zwitterionic model is required to obtain a Brønsted-Evans-Polanyi relationship between the energy barriers and reaction energies.

  15. Synthesis, X-ray crystallography, spectroscopic (FT-IR, 1H &13C NMR and UV), computational (DFT/B3LYP) and enzymes inhibitory studies of 7-hydroximinocholest-5-en-3-ol acetate

    Science.gov (United States)

    Ahmad, Faheem; Parveen, Mehtab; Alam, Mahboob; Azaz, Shaista; Malla, Ali Mohammed; Alam, Mohammad Jane; Lee, Dong-Ung; Ahmad, Shabbir

    2016-07-01

    The present study reports the synthesis of 7-Hydroximinocholest-5-en-3-ol acetate (syn. 3β-acetoxycholest-5-en-7-one oxime; in general, steroidal oxime). The identity of steroidal molecule was confirmed by NMR, FT-IR, MS, CHN microanalysis and X-ray crystallography. DFT calculations on the titled molecule have been performed. The molecular structure and spectra interpreted by Gaussian hybrid computational analysis theory (B3LYP) are found to be in good correlation with the experimental data obtained from the various spectrophotometric techniques. The vibrational bands appearing in the FTIR are assigned with great accuracy using harmonic frequencies along with intensities and animated modes. Molecular properties like HOMO-LUMO analysis, chemical reactivity descriptors, MEP mapping, dipole moment and natural atomic charges have been presented at the same level of theory. Moreover, the Hirshfeld analysis was carried out to ascertain the secondary interactions and associated 2D fingerprint plots. The percentages of various interactions are pictorialized by fingerprint plots of Hirshfeld surface. Steroidal oxime exhibited promising inhibitory activity against acetylcholinesterase (AChE) as compared to the reference drug, tacrine. Molecular docking was performed to introduce steroidal molecules into the X-ray crystal structures of acetylcholinesterase at the active site to find out the probable binding mode. The results of molecular docking admitted that steroidal oxime may exhibit enzyme inhibitor activity.

  16. Splitting a C-O bond in dialkylethers with bis(1,2,4-tri-t-butylcyclopentadienyl) cerium-hydride does not occur by a sigma-bond metathesis pathway: a combined experimental and DFT computational study

    Energy Technology Data Exchange (ETDEWEB)

    Werkema, Evan; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile; Andersen, Richard

    2010-04-06

    Addition of diethylether to [1,2,4(Me3C)3C5H2]2CeH, abbreviated Cp'2CeH, gives Cp'2CeOEt and ethane. Similarly, di-n-propyl- or di-n-butylether gives Cp'2Ce(O-n-Pr) and propane or Cp'2Ce(O-n-Bu) and butane, respectively. Using Cp'2CeD, the propane and butane contain deuterium predominantly in their methyl groups. Mechanisms, formulated on the basis of DFT computational studies, show that the reactions begin by an alpha or beta-CH activation with comparable activation barriers but only the beta-CH activation intermediate evolves into the alkoxide product and an olefin. The olefin then inserts into the Ce-H bond forming the alkyl derivative, Cp'2CeR, that eliminates alkane. The alpha-CH activation intermediate is in equilibrium with the starting reagents, Cp'2CeH and the ether, which accounts for the deuterium label in the methyl groups of the alkane. The one-step sigma-bond metathesis mechanism has a much higher activation barrier than either of the two-step mechanisms.

  17. Generalized gravity from modified DFT

    CERN Document Server

    Sakatani, Yuho; Yoshida, Kentaroh

    2016-01-01

    Recently, generalized equations of type IIB supergravity have been derived from the requirement of classical kappa-symmetry of type IIB superstring theory in the Green-Schwarz formulation. These equations are covariant under generalized T-duality transformations and hence one may expect a formulation similar to double field theory (DFT). In this paper, we consider a modification of the DFT equations of motion by relaxing a condition for the generalized covariant derivative with an extra generalized vector. In this modified double field theory (mDFT), we show that the flatness condition of the modified generalized Ricci tensor leads to the NS-NS part of the generalized equations of type IIB supergravity. In particular, the extra vector fields appearing in the generalized equations correspond to the extra generalized vector in mDFT. We also discuss duality symmetries and a modification of the string charge in mDFT.

  18. Vibrational dynamics (IR, Raman, NRVS) and DFT study of new antitumor tetranuclearstannoxanecluster, Sn(IV)$-$oxo$-${di$-$o$-$vanillin} dimethyl dichloride

    Energy Technology Data Exchange (ETDEWEB)

    Arjmand, F. [Aligarh Muslim Univ., Aligarh (India). Dept. of Chemistry; Sharma, S. [Aligarh Muslim Univ., Aligarh (India). Dept. of Chemistry; Usman, M. [Aligarh Muslim Univ., Aligarh (India). Dept. of Chemistry; Leu, B. M. [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Hu, M. Y. [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Toupet, L. [Univ. de Rennes, Rennes (France). Inst. de Physique de Rennes; Gosztola, David J. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Tabassum, S. [Aligarh Muslim Univ., Aligarh (India). Dept. of Chemistry

    2016-06-21

    The vibrational dynamics of a newly synthesized tetrastannoxane was characterized with a combination of experimental (Raman, IR and tin-based nuclear resonance vibrational spectroscopy) and computational (DFT/B3LYP) methods, with an emphasis on the vibrations of the tin sites. The cytotoxic activity revealed a significant regression selectively against the human pancreatic cell lines.

  19. Channel Estimation Algorithm Based on Wavelet De-Noising and Improved DFT%基于小波去噪与改进的DFT信道估计算法

    Institute of Scientific and Technical Information of China (English)

    张开明

    2016-01-01

    In view of the problem that traditional channel estimation algorithm based on Discrete Fourier Transform (DFT) does not eliminate the noise in the cyclic prefix length, the paper puts forward a new method of Orthogonal Frequency Division Multiplexing (OFDM) system channel estimation based on wavelet de-noising and DFT interpolation. In simulation on Matlab 2012b platform, compared with the traditional channel estimation al-gorithm based on DFT, under the conditions of the same Bit-Error-Rate (BER) or the same Mean-Square-Error (MSE) the Signal-to-Noise Rate (SNR) performance of the proposed algorithm improves a lot. The simulation re-sults show that the proposed algorithm can reduce the influence of the noise, improve the accuracy of channel esti-mation effectively, and has also have better performances than the channel estimation algorithm based on DFT.%针对基于离散傅里叶变换(DFT)信道估计算法没有消除循环前缀长度以内噪声,本文提出了一种小波去噪与改进DFT相结合的正交频分复用(OFDM)系统信道估计算法。与传统的基于DFT信道估计算法相比,在误码率相同或者均方误差相同的条件下,该算法的信噪比(SNR)有了较大的提升。仿真结果表明,该算法能较好地减小信道所受噪声的影响,并能有效提高信道估计的精确度,其总体性能比基于DFT的信道估计算法更优。

  20. ICOHR: intelligent computer based oral health record.

    Science.gov (United States)

    Peterson, L C; Cobb, D S; Reynolds, D C

    1995-01-01

    The majority of work on computer use in the dental field has focused on non-clinical practice management information needs. Very few computer-based dental information systems provide management support of the clinical care process, particularly with respect to quality management. Traditional quality assurance methods rely on the paper record and provide only retrospective analysis. Today, proactive quality management initiatives are on the rise. Computer-based dental information systems are being integrated into the care environment, actively providing decision support as patient care is being delivered. These new systems emphasize assessment and improvement of patient care at the time of treatment, thus building internal quality management into the caregiving process. The integration of real time quality management and patient care will be expedited by the introduction of an information system architecture that emulates the gathering and storage of clinical care data currently provided by the paper record. As a proposed solution to the problems associated with existing dental record systems, the computer-based patient record has emerged as a possible alternative to the paper dental record. The Institute of Medicine (IOM) recently conducted a study on improving the efficiency and accuracy of patient record keeping. As a result of this study, the IOM advocates the development and implementation of computer-based patient records as the standard for all patient care records. This project represents the ongoing efforts of The University of Iowa College of Dentistry's collaboration with the University of Uppsala Data Center, Uppsala, Sweden, on a computer-based patient dental record model. ICOHR (Intelligent Computer Based Oral Health Record) is an information system which brings together five important parts of the patient's dental record: medical and dental history; oral status; treatment planning; progress notes; and a Patient Care Database, generated from their

  1. Evolutionary Based Solutions for Green Computing

    CERN Document Server

    Kołodziej, Joanna; Li, Juan; Zomaya, Albert

    2013-01-01

    Today’s highly parameterized large-scale distributed computing systems may be composed  of a large number of various components (computers, databases, etc) and must provide a wide range of services. The users of such systems, located at different (geographical or managerial) network cluster may have a limited access to the system’s services and resources, and different, often conflicting, expectations and requirements. Moreover, the information and data processed in such dynamic environments may be incomplete, imprecise, fragmentary, and overloading. All of the above mentioned issues require some intelligent scalable methodologies for the management of the whole complex structure, which unfortunately may increase the energy consumption of such systems.   This book in its eight chapters, addresses the fundamental issues related to the energy usage and the optimal low-cost system design in high performance ``green computing’’ systems. The recent evolutionary and general metaheuristic-based solutions ...

  2. Detecting Soft Errors in Stencil based Computations

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, V. [Univ. of Utah, Salt Lake City, UT (United States); Gopalkrishnan, G. [Univ. of Utah, Salt Lake City, UT (United States); Bronevetsky, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-05-06

    Given the growing emphasis on system resilience, it is important to develop software-level error detectors that help trap hardware-level faults with reasonable accuracy while minimizing false alarms as well as the performance overhead introduced. We present a technique that approaches this idea by taking stencil computations as our target, and synthesizing detectors based on machine learning. In particular, we employ linear regression to generate computationally inexpensive models which form the basis for error detection. Our technique has been incorporated into a new open-source library called SORREL. In addition to reporting encouraging experimental results, we demonstrate techniques that help reduce the size of training data. We also discuss the efficacy of various detectors synthesized, as well as our future plans.

  3. Confidential benchmarking based on multiparty computation

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Damgård, Kasper Lyneborg; Nielsen, Kurt;

    We report on the design and implementation of a system that uses multiparty computation to enable banks to benchmark their customers' confidential performance data against a large representative set of confidential performance data from a consultancy house. The system ensures that both the banks......' and the consultancy house's data stays confidential, the banks as clients learn nothing but the computed benchmarking score. In the concrete business application, the developed prototype help Danish banks to find the most efficient customers among a large and challenging group of agricultural customers with too much...... debt. We propose a model based on linear programming for doing the benchmarking and implement it using the SPDZ protocol by Damgård et al., which we modify using a new idea that allows clients to supply data and get output without having to participate in the preprocessing phase and without keeping...

  4. Vibrational and structural observations upon 3-((1H-benzo[d]imidazol-1-yl)methyl)naphthalen-2-ol from spectral and DFT computing approaches

    Science.gov (United States)

    Jone Pradeepa, S.; Tamilvendan, D.; Susai Boobalan, Maria; Sundaraganesan, N.

    2016-05-01

    An aggregate of experimental and computational study on synthesis, molecular structure, vibrational, electronic, nuclear magnetic resonance spectra, electronic structure, NLO activity and thermochemical characterization has been investigated for 3-((1H-benzo[d]imidazol-1-yl)methyl) naphthalen-2-ol (BDMN). The perspective on structural analysis includes the examination of equilibrium geometry, Natural Bond Orbital analysis (NBO), molecular electrostatic potential (MEP) analysis and frontier molecular orbital calculation. Similarly the following spectral analysis such as vibrational (FT-IR and FT-Raman), electronic (UV-Vis) and NMR (1H and 13C) has been interpreted. The FT-IR, FT-Raman spectrum were recorded in the frequency range of 4000-400 cm-1 and 4000-50 cm-1 respectively. A complete potential energy distribution (PED) was achieved to interpret the normal modes by comparing the experimental and theoretical spectral data. The simulation of NMR spectrum was performed using GIAO strategy. The NLO activity of BDMN has been calibrated using hyperpolarizability. In addition, various thermodynamic entities were predicted against different temperatures. The entire computation was executed using appropriate model chemistries such as B3LYP/Sadlej pVTZ, B3LYP/6-311G(d,p) and PBEPBE (TDDFT)/6-311G(d,p) for the respective properties. The overall hand-in-hand analysis by using both theoretical and experimental calculation on BDMN provides interesting observations and inferences.

  5. Sonochemical synthesis and DFT studies of nano novel Schiff base cadmium complexes: Green, efficient, recyclable catalysts and precursors of Cd NPs

    Science.gov (United States)

    Parsaee, Zohreh

    2017-10-01

    Novel asymmetric (N4) Schiff bases (Ln, n = 1-3) and their nanosized cadmium complexes derived of 4,4'-(pentylazanediyl) dibenzaldehyde and aminobenzaldehyde are synthesized by sonochemical method and characterized based on physicochemical analysis including 1H NMR, 13C NMR, SEM, TGA, Mass, FT-IR, UV-Vis spectroscopy, elemental analysis, magnetic moment and molar conductance measurements. According to the analytic results of the NMR, UV-Vis and magnetic moment studies, it is found that the geometrical structures of these complexes [CdII2LnCl4], (L = C45H40N5X, X = CH3, Cl, OH) are square planer. The synthesized complexes were so effective as nanocatalyst on the oxidation of primary and secondary alcohols. The oxidation reactions were carried out in ethyl-methyl-imidazolium ionic liquid in presence of NaOCl. In addition Cd NPs were synthesized through the thermal decomposition of mentioned complexes and characterized by using FT-IR, SEM, TEM, EDX and XRD methods, which indicated close accordance to the standard pattern of CdO nanoparticles and an acceptable size at the nanorange (22-27 nm). Furthermore geometrical optimization of the Cd2LnCl4 calculated using DFT/B3LYP with LanL2DZ/6-311+G (d,p) level. The electronic parameter including HOMO-LUMO orbitals, bond gap, chemical hardness-softness, electronegativity, electrophilicity, NMR chemical shifts and IR frequencies were calculated. The calculated NMR shifts and vibrational frequencies showed excellent agreement with experimental data.

  6. Synthesis, molecular structure and vibrational analysis of D-D-A based carbazole decorated phenothiazine-3-carbaldehyde: Experimental (FT-IR, UV and NMR) and density functional theory (DFT) calculations

    Science.gov (United States)

    Karuppasamy, Ayyanar; Gokula Krishnan, Kannan; Pillai Velayutham Pillai, Muthiah; Ramalingan, Chennan

    2017-01-01

    A novel molecule, 10-(9-hexyl-9H-carbazol-3yl)-10H-phenothiazine-3-carbaldehyde (CZPTZA) has been synthesized and characterized through FT-IR, UV-Vis, NMR spectroscopic studies and molecular orbital calculations. Optimized geometrical structure, harmonic vibrational frequencies and NMR are computed with B3LYP method using 6-311++G (d,p) basis set. The geometrical parameters of the title compound obtained from Single Crystal XRD studies have been found in accord with the calculated (DFT) values. The experimentally observed vibrational frequencies are compared with the calculated ones, which were found to be in good agreement with each other. UV-Vis spectra of the title compound have also been recorded and the electronic properties, viz. excitation energies, calculated energies, oscillator strengths, frontier orbital energies and band gap energies are computed with TD-DFT/CAM-B3LYP method using 6-311++G (d,p) as the basis set. The 1H and 13C NMR chemical shifts of the molecule have been calculated by the Gauge Independent Atomic Orbital (GIAO) method and compared with the experimental outcome. Also, the values of dipole moment, polarizabilities and first order hyperpolarizabilities have been computed.

  7. Secure information transfer based on computing reservoir

    Science.gov (United States)

    Szmoski, R. M.; Ferrari, F. A. S.; de S. Pinto, S. E.; Baptista, M. S.; Viana, R. L.

    2013-04-01

    There is a broad area of research to ensure that information is transmitted securely. Within this scope, chaos-based cryptography takes a prominent role due to its nonlinear properties. Using these properties, we propose a secure mechanism for transmitting data that relies on chaotic networks. We use a nonlinear on-off device to cipher the message, and the transfer entropy to retrieve it. We analyze the system capability for sending messages, and we obtain expressions for the operating time. We demonstrate the system efficiency for a wide range of parameters. We find similarities between our method and the reservoir computing.

  8. Prestandardisation Activities for Computer Based Safety Systems

    DEFF Research Database (Denmark)

    Taylor, J. R.; Bologna, S.; Ehrenberger, W.

    1981-01-01

    Questions of technical safety become more and more important. Due to the higher complexity of their functions computer based safety systems have special problems. Researchers, producers, licensing personnel and customers have met on a European basis to exchange knowledge and formulate positions....... The Commission of the european Community supports the work. Major topics comprise hardware configuration and self supervision, software design, verification and testing, documentation, system specification and concurrent processing. Preliminary results have been used for the draft of an IEC standard and for some...

  9. [Characteristic vibration analysis of M-RNA nucleic acid bases complexes (M = Ca+ and Mg+) by DFT].

    Science.gov (United States)

    Zhang, Xing-Chu; Hu, Yi-Hua; Wang, Xiao-Juan

    2009-01-01

    A density functional investigation of the interaction between calcium and magnesium univalent cations and RNA pyrimidine base (cytosine, thymine and uracil) was performed to determine geometric coordinates and free energies for all possible stable isomers at B3LYP/6-311 + G (2df, 2p) level. The most stable isomers C1M, T1M and U1M (M = Ca+ and Mg+) with the lowest free energy among the same pyrimidine base tautomers were calculated to determine the characters of infrared vibrations. According to the results, two characteristic infrared vibrations at wave numbers 1,684 and 1,765 cm(-1) were found for single pyrimidine base C1, at 1,747 and 1,792 cm(-1) for T1, 1,763 and at 1,796 cm(-1) for U1. In addition, spectrum shifts were found when the cations interact with the pyrimidine base tautomers. For deeper analysis, we found that when the stable complexes are formed, the cations are prone to act on the oxygen atoms, and cause the vibrational frequencies to change, the spectral lines belonging to the vibration of C--O--M turn out to redshift and the others turn out to blueshift. When the stable complex C1M is formed, the characteristic infrared vibration at 1,684 cm(-1) mainly caused by the ring's vibration turns out to blueshift about 10 cm(-1), and the another characteristic vibration of 1,765 cm(-1) caused by vibration of bond C--O with oxygen atom acting on cations directly turns out to redshift by 112 cm(-1) for complex C1Ca+ and by 110 cm(-1) for C1Mg+. When the stable complexes T1M are formed, the characteristic vibration of bond C--O--M turns out to redshift about 130 cm(-1) and the vibration of bond C--O turns out to blueshift about 55 cm(-1). When the stable complexes U1M are formed, the vibration of bond C--O--M turns out to redshift about 90 cm(-1) and about 50 cm(-1) for another C--O. The characteristic infrared vibration frequencies are changed obviously when tautomers act on the cations, which is mainly because cations take part in molecule's vibrations

  10. Computer Profiling Based Model for Investigation

    Directory of Open Access Journals (Sweden)

    Neeraj Choudhary

    2011-10-01

    Full Text Available Computer profiling is used for computer forensic analysis, and proposes and elaborates on a novel model for use in computer profiling, the computer profiling object model. The computer profiling object model is an information model which models a computer as objects with various attributes and inter-relationships. These together provide the information necessary for a human investigator or an automated reasoning engine to make judgments as to the probable usage and evidentiary value of a computer system. The computer profiling object model can be implemented so as to support automated analysis to provide an investigator with the informationneeded to decide whether manual analysis is required.

  11. Chiral vanadium(V) complexes with 2-aminoglucose Schiff-base ligands and their solution configurations: synthesis, structures, and DFT calculations.

    Science.gov (United States)

    Mohammadnezhad, Gholamhossein; Böhme, Michael; Geibig, Daniel; Burkhardt, Anja; Görls, Helmar; Plass, Winfried

    2013-09-01

    The sugar-modified Schiff-base ligands derived from benzyl 2-deoxy-2-salicylideneamino-α-D-glucopyranoside (H2L(5-Br) and H2L(3-OMe)) were used to prepare the chiral oxidovanadium(V) complexes [VO(L(5-Br))(OMe)] (1) and [VO(L(3-OMe))(OMe)] (2) which can be isolated from a methanol solution as the six-coordinate complexes with an additional methanol ligand [VO(L(5-Br))(OMe)(MeOH)] (1-MeOH) and [VO(L(3-OMe))(OMe) (MeOH)] (2-MeOH). Both complexes crystallize in the orthorhombic space group P2(1)2(1)2(1) together with two solvent molecules of methanol as 1-MeOH·2MeOH and 1-MeOH·2MeOH. In both crystal structures, only diastereomers with A configuration at the chiral vanadium centre (OC-6-24-A) are observed which corresponds to an cis configuration of the oxido group at the vanadium centre and the benzyl group at the anomeric carbon of the sugar backbone. Upon recrystallization of 2-MeOH from chloroform, the five-coordinate complex 2 was obtained which crystallizes in the monoclinic space group P2(1) with one co-crystallized chloroform molecule (2·CHCl3). For the chiral vanadium centre in 2·CHCl3, a C configuration (SPY-5-43-C) is observed which corresponds to an trans structure as far as the orientations of the oxido and benzyl groups are concerned. (1)H and (51)V NMR spectra of 1 and 2 indicate the presence of two diastereomers in solution. Their absolute configurations can be assigned based on the magnetic anisotropy effect of the oxidovanadium group. This effect leads to significant differences for the (1)H NMR chemical shifts of the H-2 (1.1 ppm) and H-3 protons (0.3 ppm) of the glucose backbone of the two diastereomers, with the downfield shift observed for the H-2 proton of the C-configured and the H-3 proton of the A-configured diastereomer at the vanadium centre. For 1 and 2 the difference between the (51)V NMR chemical shifts of the two diastereomers is 30 and 28 ppm, respectively. Also in the (13)C NMR significant chemical shift differences between the

  12. Vibrational spectra and DFT calculations of the vibrational modes of Schiff base C18H17N3O2

    Science.gov (United States)

    Antunes, J. A.; Silva, L. E.; Bento, R. R. F.; Teixeira, A. M. R.; Freire, P. T. C.; Faria, J. L. B.; Ramos, R. J.; Silva, C. B.; Lima, J. A.

    2012-04-01

    The Schiff base 4-{[(1E)-(2-Hydroxyphenyl)methylidene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (C18H17N3O2) is a synthetic compound with a variety of scientific and technological applications, such as clinic, analytic and pharmacologic. In this work FT-Raman spectrum and FT-infrared spectrum of C18H17N3O2 were investigated at 300 K. Vibrational wavenumber and wave vector have been predicted using Density Functional Theory (B3LYP) calculations with the 6-31 G(d,p) basis set. The description of the normal modes was performed by means of the potential energy distribution. A comparison with experiment allowed us to assign most of the normal modes of the crystal.

  13. Influence of xc functional on thermal-elastic properties of metal oxides: A DFT-based Debye-Gr"uneisen model approach

    Science.gov (United States)

    Lee, Taehun; Soon, Aloysius

    2012-02-01

    For high-temperature applications, the chemical stability, as well as the mechanical integrity of the oxide material used is of utmost importance. Solving these problems demands a thorough and fundamental understanding of their thermal-elastic properties. In this work, we report density-functional theory (DFT) calculations to investigate the influence of the xc functional on specific thermal-elastic properties of some common oxides CeO2, Cu2O, and MgO. Namely, we consider the local-density approximation (LDA), the generalized gradient approximation due to Perdew, Burke, and Ernzerhof (GGA-PBE), as well as a recently popularized hybrid functional due to Heyd-Scuseria-Ernzehof (HSE06). In addition, we will also report DFT+U results where we introduce a Hubbard U term to the Cu 3d and the Ce 4f states. Upon obtaining the DFT total energies, we then couple this to a volume-dependent Debye-Gr"uneisen model [1] to determine the thermodynamic quantities of these oxides at arbitrary pressures and temperatures. We find an explicit description of the strong correlation (e.g. via the DFT+U approach and using HSE06) is necessary to have a good agreement with experimental values. [1] A. Otero-de-la-Roza, D. Abbasi-P'erez et al. Com. Phys. Com. 182 (2011) 2232

  14. Base or nucleophile? DFT finally elucidates the origin of the selectivity between the competitive reactions triggered by MeLi or LDA on propanal.

    Science.gov (United States)

    Marchois, J; Fressigné, C; Lecachey, B; Maddaluno, J

    2015-06-18

    The competition between basicity and nucleophilicity of two standard organolithium reagents was studied using DFT. Comparing the reactivity of solvated (MeLi)2 and (LDA)2 toward propanal finally explains why methyllithium adds onto the carbonyl while LDA deprotonates the α-position, in accord with experiment and Ireland's deprotonation TS.

  15. A DFT-based comparative equilibrium study of thermal dehydration and hydrolysis of CaCl₂ hydrates and MgCl₂ hydrates for seasonal heat storage.

    Science.gov (United States)

    Pathak, Amar Deep; Nedea, Silvia; Zondag, Herbert; Rindt, Camilo; Smeulders, David

    2016-04-21

    Salt hydrates store solar energy in chemical form via a reversible dehydration-hydration reaction. However, as a side reaction to dehydration, hydrolysis (HCl formation) may occur in chloride based salt hydrates (specially in MgCl2 hydrates), affecting the durability of the storage system. The mixture of CaCl2 and MgCl2 hydrates has been shown experimentally to have exceptional cycle stability and improved kinetics. However, the optimal operating conditions for the mixture are unknown. To understand the appropriate balance between dehydration and hydrolysis kinetics in the mixtures, it is essential to gain in-depth insight into the mixture components. We present a GGA-DFT level study to investigate the various gaseous structures of CaCl2 hydrates and to understand the relative stability of their conformers. The hydration strength and relative stability of conformers are dominated by electrostatic interactions. A wide network of intramolecular homonuclear and heteronuclear hydrogen bonds is observed in CaCl2 hydrates. Equilibrium product concentrations are obtained during dehydration and hydrolysis reactions under various temperature and pressure conditions. The trend of the dehydration curve with temperature in CaCl2 hydrates is similar to the experiments. Comparing these results to those of MgCl2 hydrates, we find that CaCl2 hydrates are more resistant towards hydrolysis in the temperature range of 273-800 K. Specifically, the present study reveals that the onset temperatures of HCl formation, a crucial design parameter for MgCl2 hydrates, are lower than for CaCl2 hydrates except for the mono-hydrate.

  16. Computer Animation Based on Particle Methods

    Directory of Open Access Journals (Sweden)

    Rafal Wcislo

    1999-01-01

    Full Text Available The paper presents the main issues of a computer animation of a set of elastic macroscopic objects based on the particle method. The main assumption of the generated animations is to achieve very realistic movements in a scene observed on the computer display. The objects (solid bodies interact mechanically with each other, The movements and deformations of solids are calculated using the particle method. Phenomena connected with the behaviour of solids in the gravitational field, their defomtations caused by collisions and interactions with the optional liquid medium are simulated. The simulation ofthe liquid is performed using the cellular automata method. The paper presents both simulation schemes (particle method and cellular automata rules an the method of combining them in the single animation program. ln order to speed up the execution of the program the parallel version based on the network of workstation was developed. The paper describes the methods of the parallelization and it considers problems of load-balancing, collision detection, process synchronization and distributed control of the animation.

  17. HiPPI-based parallel computing

    Science.gov (United States)

    Jung, Charles C.

    1993-02-01

    The IBM Enhanced Clustered Fortran (ECF) advanced technology project combines parallel computing technology with a HiPPI-based LAN network. The ECF environment is a clustered, parallel computing environment which consists of IBM ES/90001 complexes and possibly other parallel machines connected by HiPPI. The ECF software, including the language processor, is independent of hardware architectures, operating systems, and the Fortran compiler and runtime library. The ECF software is highly portable because it is based on well-known, standard technology and transport protocols such as Remote Procedure Call (RPC), X/Open Transport Interface (XTI), and TCP/IP. The ECF software is transport-independent, and can accommodate other transport protocols concurrently. This paper describes the IBM ECF environment including the language extensions, the programming model, and the software layers and components. Also, this paper explains how to achieve portability and scalability. Lastly, this paper describes how effective task communication is accomplished in ECF through RPC, XTI, TCP/IP, and a customized enhancement over HiPPI. An analysis of network performance in terms of bottleneck conditions is presented, and empirical data indicating improved throughput is provided. Comparisons to alternative methodologies and technologies are also presented.

  18. Noise-based communication and computing

    CERN Document Server

    Kish, Laszlo B

    2008-01-01

    We discuss the speed-error-heat triangle and related problems with rapidly increasing energy dissipation and error rate during miniaturization. These and the independently growing need of unconditional data security have provoked non-conventional approaches in the physics of informatics. Noise-based informatics is a potentially promising possibility which is the way how biological brains process the information. Recently, it has been shown that thermal noise and its electronically enhanced versions (Johnson-like noises) can be utilized as information carrier with peculiar properties. Relevant examples are Zero power (stealth) communication, Unconditionally secure communication with Johnson(-like) noise and Kirchhoff loop and Noise-driven computing. The zero power communication utilizes the equilibrium background noise in the channel to transfer information. The unconditionally secure communication is based on the properties of Johnson(-like) noise and those of a simple Kirchhoff's loop. The scheme utilizes on...

  19. Computational algebraic topology-based video restoration

    Science.gov (United States)

    Rochel, Alban; Ziou, Djemel; Auclair-Fortier, Marie-Flavie

    2005-03-01

    This paper presents a scheme for video denoising by diffusion of gray levels, based on the Computational Algebraic Topology (CAT) image model. The diffusion approach is similar to the one used to denoise static images. Rather than using the heat transfer partial differential equation, discretizing it and solving it by a purely mathematical process, the CAT approach considers the global expression of the heat transfer and decomposes it into elementary physical laws. Some of these laws describe conservative relations, leading to error-free expressions, whereas others depend on metric quantities and require approximation. This scheme allows for a physical interpretation for each step of the resolution process. We propose a nonlinear and an anisotropic diffusion algorithms based on the extension to video of an existing 2D algorithm thanks to the flexibility of the topological support. Finally it is validated with experimental results.

  20. New π-Conjugated Materials Based on Furylenevinylene Candidate for Organic Solar Cells Application: A DFT Study

    Directory of Open Access Journals (Sweden)

    El Alamy Aziz

    2015-12-01

    Full Text Available The specific properties of organic-conjugated molecules and polymers are of great importance since they have become the most promising materials for the optoelectronic device technology such as solar cells. The use of low band gap materials is a viable method for better harvesting of the solar spectrum and increasing its efficiency. The control of the parameters of these materials is a research issue of ongoing interest. In this work, a quantum chemical investigation was performed to explore the optical and electronic properties of a series of different compounds based on furylenevinylene. Different electron side groups were introduced to investigate their effects on the electronic structure. The theoretical knowledge of the highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO energy levels of the components is basic in studying organic solar cells; so the HOMO, LUMO, Gap energy and open circuit voltage (Voc of the studied compounds have been calculated and reported. These properties suggest that these materials behave as good candidate for organic solar cells. DOI: http://dx.doi.org/10.17807/orbital.v7i4.763 

  1. Synthesis and crystal structure of 3-(4‧-nitrophenyl)iminocoumarin, and cyclization reaction mechanism based on DFT calculation

    Science.gov (United States)

    Zhang, Chao-Zhi; Li, Shi-Juan; Cao, Hui; Song, Ming-Xia; Kong, Qing-Gang

    2015-05-01

    A convenient method was reported to synthesize 3-(4‧-nitrophenyl)iminocoumarin by a cyclization reaction following a Knoevenagel reaction of 2-hydroxybenzaldehyde with 4-nitrophenylacenitrile in an ethanol solution. Piperidine or piperazine was employed respectively as catalyst. Crystal structure of 3-(4‧-nitrophenyl)iminocoumarin shows that the molecules are H-aggregation due to π-π stacking and hydrogen bonds between adjacent molecules, as a result, electrons would transfer easily from a molecule to an adjacent molecule. Based on theoretical calculations of the electronic structures and thermodynamic parameters of the reactive intermediates in these cyclization reactions, the reaction mechanisms were postulated. Data of single crystal and spectrum of UV-vis absorption show that 3-(4‧-nitrophenyl)iminocoumarin is good π-conjugated compound and would be potentially employed as donor-acceptor polymer units for developing bulk heterojunction solar cell. This paper suggests a convenient and effective method for synthesizing ring-locked D-A copolymer units for developing solar cell materials.

  2. Computer Based Information Systems and the Middle Manager.

    Science.gov (United States)

    Why do some computer based information systems succeed while others fail. It concludes with eleven recommended areas that middle management must...understand in order to effectively use computer based information systems . (Modified author abstract)

  3. Object Based Middleware for Grid Computing

    Directory of Open Access Journals (Sweden)

    S. Muruganantham

    2010-01-01

    Full Text Available Problem statement: “Grid” computing has emerged as an important new field, distinguished from conventional distributed computing by its focus on large-scale resource sharing, innovative applications and, in some cases, high-performance orientation. The role of middleware is to ease the task of designing, programming and managing distributed applications by providing a simple, consistent and integrated distributed programming environment. Essentially, middleware is a distributed software layer, which abstracts over the complexity and heterogeneity of the underlying distributed environment with its multitude of network technologies, machine architectures, operating systems and programming languages. Approach: This study brought out the development of supportive middleware to manage resources and distributed workload across multiple administrative boundaries is of central importance to Grid computing. Active middleware services that perform look-up, scheduling and staging are being developed that allow users to identify and utilize appropriate resources that provide sustainable system and user-level qualities of service. Results: Different middleware platforms support different programming models. Perhaps the most popular model is object-based middleware in which applications are structured into objects that interact via location transparent method invocation. Conclusion: The Object Management Group’s CORBA platform offer an Interface Definition Language (IDL which is used to abstract over the fact that objects can be implemented in any suitable programming language, an object request broker which is responsible for transparently directing method invocations to the appropriate target object and a set of services such as naming, time, transactions, replication which further enhance the programming environment.

  4. Computing Gröbner Bases within Linear Algebra

    Science.gov (United States)

    Suzuki, Akira

    In this paper, we present an alternative algorithm to compute Gröbner bases, which is based on computations on sparse linear algebra. Both of S-polynomial computations and monomial reductions are computed in linear algebra simultaneously in this algorithm. So it can be implemented to any computational system which can handle linear algebra. For a given ideal in a polynomial ring, it calculates a Gröbner basis along with the corresponding term order appropriately.

  5. Liquid Methanol from DFT and DFT/MM Molecular Dynamics Simulations.

    Science.gov (United States)

    Sieffert, Nicolas; Bühl, Michael; Gaigeot, Marie-Pierre; Morrison, Carole A

    2013-01-08

    We present a comparative study of computational protocols for the description of liquid methanol from ab initio molecular dynamics simulations, in view of further applications directed at the modeling of chemical reactivity of organic and organometallic molecules in (explicit) methanol solution. We tested density functional theory molecular dynamics (DFT-MD) in its Car-Parrinello Molecular Dynamics (CPMD) and Quickstep/Born-Oppenheimer MD (CP2K) implementations, employing six popular density functionals with and without corrections for dispersion interactions (namely BLYP, BLYP-D2, BLYP-D3, BP86, BP86-D2, and B97-D2). Selected functionals were also tested within the two QM/MM frameworks implemented in CPMD and CP2K, considering one DFT molecule in a MM environment (described by the OPLS model of methanol). The accuracy of each of these methods at describing the bulk liquid phase under ambient conditions was evaluated by analyzing their ability to reproduce (i) the average structure of the liquid, (ii) the mean squared displacement of methanol molecules, (iii) the average molecular dipole moments, and (iv) the gas-to-liquid red-shift observed in their infrared spectra. We show that it is difficult to find a DFT functional that describes these four properties equally well within full DFT-MD simulations, despite a good overall performance of B97-D2. On the other hand, DFT/MM-MD provides a satisfactory description of the solvent-solute polarization effects with all functionals and thus represents a good alternative for the modeling of methanol solutions in the context of chemical reactivity in an explicit environment.

  6. COMPUTER-BASED REASONING SYSTEMS: AN OVERVIEW

    Directory of Open Access Journals (Sweden)

    CIPRIAN CUCU

    2012-12-01

    Full Text Available Argumentation is nowadays seen both as skill that people use in various aspects of their lives, as well as an educational technique that can support the transfer or creation of knowledge thus aiding in the development of other skills (e.g. Communication, critical thinking or attitudes. However, teaching argumentation and teaching with argumentation is still a rare practice, mostly due to the lack of available resources such as time or expert human tutors that are specialized in argumentation. Intelligent Computer Systems (i.e. Systems that implement an inner representation of particular knowledge and try to emulate the behavior of humans could allow more people to understand the purpose, techniques and benefits of argumentation. The proposed paper investigates the state of the art concepts of computer-based argumentation used in education and tries to develop a conceptual map, showing benefits, limitation and relations between various concepts focusing on the duality “learning to argue – arguing to learn”.

  7. Fabrication of an electrochemical sensor based on computationally designed molecularly imprinted polymer for the determination of mesalamine in real samples

    Energy Technology Data Exchange (ETDEWEB)

    Torkashvand, M. [Department of Analytical Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Gholivand, M.B., E-mail: mbgholivand@yahoo.com [Department of Analytical Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Taherkhani, F. [Department of Physical Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of)

    2015-10-01

    A novel electrochemical sensor based on mesalamine molecularly imprinted polymer (MIP) film on a glassy carbon electrode was fabricated. Density functional theory (DFT) in gas and solution phases was developed to study the intermolecular interactions in the pre-polymerization mixture and to find the suitable functional monomers in MIP preparation. On the basis of computational results, o-phenylenediamine (OP), gallic acid (GA) and p-aminobenzoic acid (ABA) were selected as functional monomers. The MIP film was cast on glassy carbon electrode by electropolymerization of solution containing ternary monomers and then followed by Ag dendrites (AgDs) with nanobranch deposition. The surface feature of the modified electrode (AgDs/MIP/GCE) was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Under the optimal experimental conditions, the peak current was proportional to the concentration of mesalamine ranging from 0.05 to 100 μM, with the detection limit of 0.015 μM. The proposed sensor was applied successfully for mesalamine determination in real samples. - Highlights: • The determination of MES using AgDs/MIP/GCE is reported for the first time. • The computer assisted design of terpolymer MIPs was used to screen monomers. • Theoretical results of DFT approach were in agreement with experimental results. • The sensor displayed a high selectivity for template in the presence of interferes. • The developed sensor has been applied to determine mesalamine in real samples.

  8. An Applet-based Anonymous Distributed Computing System.

    Science.gov (United States)

    Finkel, David; Wills, Craig E.; Ciaraldi, Michael J.; Amorin, Kevin; Covati, Adam; Lee, Michael

    2001-01-01

    Defines anonymous distributed computing systems and focuses on the specifics of a Java, applet-based approach for large-scale, anonymous, distributed computing on the Internet. Explains the possibility of a large number of computers participating in a single computation and describes a test of the functionality of the system. (Author/LRW)

  9. Intelligent Image Based Computer Aided Education (IICAE)

    Science.gov (United States)

    David, Amos A.; Thiery, Odile; Crehange, Marion

    1989-03-01

    Artificial Intelligence (AI) has found its way into Computer Aided Education (CAE), and there are several systems constructed to put in evidence its interesting advantages. We believe that images (graphic or real) play an important role in learning. However, the use of images, outside their use as illustration, makes it necessary to have applications such as AI. We shall develop the application of AI in an image based CAE and briefly present the system under construction to put in evidence our concept. We shall also elaborate a methodology for constructing such a system. Futhermore we shall briefly present the pedagogical and psychological activities in a learning process. Under the pedagogical and psychological aspect of learning, we shall develop areas such as the importance of image in learning both as pedagogical objects as well as means for obtaining psychological information about the learner. We shall develop the learner's model, its use, what to build into it and how. Under the application of AI in an image based CAE, we shall develop the importance of AI in exploiting the knowledge base in the learning environment and its application as a means of implementing pedagogical strategies.

  10. Synthesis, crystal structure, Hirshfeld surface analysis, electronic structure through DFT study and fluorescence properties of a new anthracene based organic tecton

    Science.gov (United States)

    Pal, Nilasish; Singha, Debabrata; Jana, Atish Dipankar

    2017-10-01

    A new organic molecule 9,10-bis((2-(pyridin-2-yl)-1H-imidazol-1-yl)methyl)anthracene (APIM) has been synthesized. Crystal structure analysis of the molecular solid reveals that CH⋯π and π⋯π interactions are the molecular packing forces in the solid state. Thermal analysis of the molecular solid shows relatively higher decomposition temperature of the crystalline molecular solid that correlates well with the cooperative nature of CH⋯π and π⋯π interactions. Density Functional Theory (DFT) optimized structure of the molecule closely correlates with that found in the crystal. DFT optimizations also lead to the similar CH⋯π and π⋯π interaction motifs that are found within the crystal. Hirshfeld surface analysis provides detailed insight into the relative importance of various weak forces in the molecular packing. Study of the fluorescence behavior of the molecules shows quenching in the presence of metal ions.

  11. Does Fe(2+) in olivine-based interstellar grains play any role in the formation of H2? Atomistic insights from DFT periodic simulations.

    Science.gov (United States)

    Navarro-Ruiz, J; Ugliengo, P; Sodupe, M; Rimola, A

    2016-05-25

    Using periodic DFT-D2 methods, atomistic simulations of interstellar H adsorption and H2 formation on a (010) Fe-containing olivine surface are presented. At variance with the (010) Mg2SiO4 surface and key to these processes are the large Fe/H interaction energies, suggesting that olivine surfaces are good reservoirs of H atoms for subsequent recombination to form H2.

  12. Information Integration Method Based on Intermediary DFT%基于中性DFT的信息集成实现方法

    Institute of Scientific and Technical Information of China (English)

    万麟瑞; 李绪蓉

    2000-01-01

    该文探讨采用中性数据格式转换(DFT)机制实现CIMS信息集成的接口软件开发方法,提出DFT模型设计与实现的具体方案.所开发的集成接口在863/CIMS实际应用中取得了良好的效果.

  13. 1-(2-Chlorobenzyloxy-3-[1,2,3]triazol-1-yl-propan-2-ol Derivatives: Synthesis, Characterization, and DFT-Based Descriptors Analysis

    Directory of Open Access Journals (Sweden)

    Eloisa Román-Maldonado

    2017-01-01

    Full Text Available A novel series of 1-(2-chlorobenzyloxy-3-[1,2,3]triazol-1-yl-propan-2-ol derivatives was designed and synthesized using copper catalyzed alkyne-azide cycloaddition in the key step. Theoretical investigation of molecular and electronic properties by means of global and local reactivity indexes of the synthetized compounds was carried out, using DFT (Density Functional Theory at PBEPBE/6-31++G⁎⁎ level.

  14. Demystifying the GMAT: Computer-Based Testing Terms

    Science.gov (United States)

    Rudner, Lawrence M.

    2012-01-01

    Computer-based testing can be a powerful means to make all aspects of test administration not only faster and more efficient, but also more accurate and more secure. While the Graduate Management Admission Test (GMAT) exam is a computer adaptive test, there are other approaches. This installment presents a primer of computer-based testing terms.

  15. A Granular Computing Model Based on Tolerance relation

    Institute of Scientific and Technical Information of China (English)

    WANG Guo-yin; HU Feng; HUANG Hai; WU Yu

    2005-01-01

    Granular computing is a new intelligent computing theory based on partition of problem concepts. It is an important problem in Rough Set theory to process incomplete information systems directly. In this paper, a granular computing model based on tolerance relation for processing incomplete information systems is developed. Furthermore, a criteria condition for attribution necessity is proposed in this model.

  16. Measurement-Based and Universal Blind Quantum Computation

    Science.gov (United States)

    Broadbent, Anne; Fitzsimons, Joseph; Kashefi, Elham

    Measurement-based quantum computation (MBQC) is a novel approach to quantum computation where the notion of measurement is the main driving force of computation. This is in contrast with the more traditional circuit model which is based on unitary operation. We review here the mathematical model underlying MBQC and the first quantum cryptographic protocol designed using the unique features of MBQC.

  17. Computer-Based Cognitive Tools: Description and Design.

    Science.gov (United States)

    Kennedy, David; McNaught, Carmel

    With computers, tangible tools are represented by the hardware (e.g., the central processing unit, scanners, and video display unit), while intangible tools are represented by the software. There is a special category of computer-based software tools (CBSTs) that have the potential to mediate cognitive processes--computer-based cognitive tools…

  18. Why use DFT methods in the study of carbohydrates?

    Science.gov (United States)

    The recent advances in density functional theory (DFT) and computer technology allow us to study systems with more than 100 atoms routinely. This makes it feasible to study large carbohydrate molecules via quantum mechanical methods, whereas in the past, studies of carbohydrates were restricted to ...

  19. Structural flexibility of DABCO. Ab initio and DFT benchmark study

    Science.gov (United States)

    Nizovtsev, Anton S.; Ryzhikov, Maxim R.; Kozlova, Svetlana G.

    2017-01-01

    The energy and structural parameters of 1,4-diazabicyclo[2.2.2]octane (DABCO) obtained by various DFT methods are examined versus ab initio and experimental data. The features of twisting potentials of DABCO and closely-related species (1-azabicyclo[2.2.2]octane and bicyclo[2.2.2]octane) are discussed in light of computational schemes applied.

  20. Hamilton Graph Based on DNA Computing

    Institute of Scientific and Technical Information of China (English)

    ZHANGJia-xiu

    2004-01-01

    DNA computing is a novel method for solving a class of intractable computationalproblems in which the computing can grow exponentially with problem size. Up to now, manyaccomplishments have been achieved to improve its performance and increase its reliability.Hamilton Graph Problem has been solved by means of molecular biology techniques. A smallgraph was encoded in molecules of DNA, and the “operations” of the computation wereperformed with standard protocols and enzymes. This work represents further evidence forthe ability of DNA computing to solve NP-complete search problems.

  1. A quantum computer based on recombination processes in microelectronic devices

    Science.gov (United States)

    Theodoropoulos, K.; Ntalaperas, D.; Petras, I.; Konofaos, N.

    2005-01-01

    In this paper a quantum computer based on the recombination processes happening in semiconductor devices is presented. A "data element" and a "computational element" are derived based on Schokley-Read-Hall statistics and they can later be used to manifest a simple and known quantum computing process. Such a paradigm is shown by the application of the proposed computer onto a well known physical system involving traps in semiconductor devices.

  2. A quantum computer based on recombination processes in microelectronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Theodoropoulos, K [Computer Engineering and Informatics Department, University of Patras, Patras (Greece); Ntalaperas, D [Computer Engineering and Informatics Department, University of Patras, Patras (Greece); Research Academic Computer Technology Institute, Riga Feraiou 61, 26110, Patras (Greece); Petras, I [Computer Engineering and Informatics Department, University of Patras, Patras (Greece); Konofaos, N [Computer Engineering and Informatics Department, University of Patras, Patras (Greece)

    2005-01-01

    In this paper a quantum computer based on the recombination processes happening in semiconductor devices is presented. A 'data element' and a 'computational element' are derived based on Schokley-Read-Hall statistics and they can later be used to manifest a simple and known quantum computing process. Such a paradigm is shown by the application of the proposed computer onto a well known physical system involving traps in semiconductor devices.

  3. Natural Languages Processing for Building Computer-based Learning Tools

    Institute of Scientific and Technical Information of China (English)

    张颖; 李娜

    2015-01-01

    This paper outlines a framework to use computer and natural language techniques for various levels of learners to learn foreign languages in Computer-based Learning environment. We propose some ideas for using the computer as a practical tool for learning foreign language where the most of courseware is generated automatically. We then describe how to build Computer-based Learning tools, discuss its effectiveness, and conclude with some possibilities using on-line resources.

  4. Molecular orbital studies (hardness, chemical potential and electrophilicity), vibrational investigation and theoretical NBO analysis of 4-4'-(1H-1,2,4-triazol-1-yl methylene) dibenzonitrile based on abinitio and DFT methods.

    Science.gov (United States)

    Sheela, N R; Muthu, S; Sampathkrishnan, S

    2014-01-01

    The Fourier transform infrared (FTIR) and FT Raman (FTR) of 4-4'-(1H-1, 2, 4-triazol-1-yl methylene) dibenzonitrile (4-HTMDBN) have been recorded and analyzed. The equilibrium geometry harmonic vibrational frequencies have been investigated with the help of standard HF and DFT methods with 6-31G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). Theoretical simulations of the FTIR and FTR spectra of the title compound have been calculated. The (1)H and (13)C Nuclear Magnetic Resonance (NMR) chemical shifts of the molecule were calculated by the Gauge including atomic orbital (GIAO) method. The stability of the molecule has been analyzed using natural bond orbital (NBO) analysis. The linear polarizability (α) and the first order hyperpolarizability (β) values of the investigated molecule have been computed using HF/DFT/6-31G(d,p) methods on the finite field approach. UV-Vis spectrum of the compound is recorded and the electronic properties such as HOMO and LUMO energies, are performed. The directly calculated ionization potential (IP), electron affinity (EA), electronegativity (χ), electrophilicity index (ω), hardness (η) and chemical potential (ρ) are all correlated with the HOMO and LUMO energies with their molecular properties. Mulliken population analysis on atomic charges, molecular electrostatic potential maps (MEP) and thermodynamical properties of title compound at different temperature have been calculated.

  5. NIR-FT Raman, FT-IR and surface-enhanced Raman scattering and DFT based theoretical studies on the adsorption behaviour of (S)-Phenylsuccinic acid on silver nanoparticles

    Indian Academy of Sciences (India)

    D Sajan; V Bena Jothy; Thomas Kuruvilla; I Hubert Joe

    2010-07-01

    Single crystals of ()-phenylsuccinic acid (SPSA) were grown by the slow evaporation technique and vibrational spectral analysis was carried out using near-IR Fourier transform Raman and Fourier transform IR spectroscopy. The density functional theoretical (DFT) computations were also performed at the B3LYP/6-311G(d, p) level to derive the equilibrium geometry, vibrational wavenumbers and intensities. Vibrational spectral investigation confirmed the formation of cyclic dimers in the crystal, with the carboxyl groups of each acid molecule being hydrogen bonded to those of the adjacent molecules. The Raman vibrational wavenumbers of the adsorption geometry of (S)-phenylsuccinic acid (SPSA) on a silver surface have been simulated using DFT-B3PW91 with lanl2dz basis set and it compared with the experimental spectrum. The large enhancement of in-plane bending and ring breathing modes in the surface-enhanced Raman scattering spectrum indicates that the molecule is adsorbed on the silver surface in an `at least vertical’ or slightly tilted orientation, with the ring perpendicular to the silver surface. The calculated vibrational spectra are in agreement with experimental values confirming the validity of the proposed adsorption configurations.

  6. Data Mining Based on Computational Intelligence

    Institute of Scientific and Technical Information of China (English)

    WANG Yuan-zhen; ZHANG Zhi-bing; YI Bao-lin; LI Hua-yang

    2005-01-01

    This paper combines computational intelligence tools: neural network, fuzzy logic, and genetic algorithm to develop a data mining architecture (NFGDM), which discov ers patterns and represents them in understandable forms. In the NFGDM, input data are preprocessed by fuzzification, the preprocessed data of input variables are then used to train a radial basis probabilistic neural network to classify the dataset according to the classes considered. A rule extraction technique is then applied in order to extract explicit knowledge from the trained neural networks and represent it in the form of fuzzy if-then rules. In the final stage, genetic algorithm is used as a rule-pruning module to eliminate those weak rules that are still in the rule bases. Comparison with some knownneural network classifier, the architecture has fast learning speed, and it is characterized by the incorporation of the possibility information into the consequents of classification rules in human understandable forms. The experiments show that the NFGDM is more efficient and more robust than traditional decision tree method.

  7. Progress in silicon-based quantum computing.

    Science.gov (United States)

    Clark, R G; Brenner, R; Buehler, T M; Chan, V; Curson, N J; Dzurak, A S; Gauja, E; Goan, H S; Greentree, A D; Hallam, T; Hamilton, A R; Hollenberg, L C L; Jamieson, D N; McCallum, J C; Milburn, G J; O'Brien, J L; Oberbeck, L; Pakes, C I; Prawer, S D; Reilly, D J; Ruess, F J; Schofield, S R; Simmons, M Y; Stanley, F E; Starrett, R P; Wellard, C; Yang, C

    2003-07-15

    We review progress at the Australian Centre for Quantum Computer Technology towards the fabrication and demonstration of spin qubits and charge qubits based on phosphorus donor atoms embedded in intrinsic silicon. Fabrication is being pursued via two complementary pathways: a 'top-down' approach for near-term production of few-qubit demonstration devices and a 'bottom-up' approach for large-scale qubit arrays with sub-nanometre precision. The 'top-down' approach employs a low-energy (keV) ion beam to implant the phosphorus atoms. Single-atom control during implantation is achieved by monitoring on-chip detector electrodes, integrated within the device structure. In contrast, the 'bottom-up' approach uses scanning tunnelling microscope lithography and epitaxial silicon overgrowth to construct devices at an atomic scale. In both cases, surface electrodes control the qubit using voltage pulses, and dual single-electron transistors operating near the quantum limit provide fast read-out with spurious-signal rejection.

  8. Computer Based Training Authors' and Designers' training

    Directory of Open Access Journals (Sweden)

    Frédéric GODET

    2016-03-01

    Full Text Available This communication, through couple of studies driven since 10 years, tries to show how important is the training of authors in Computer Based Training (CBT. We submit here an approach to prepare designers mastering Interactive Multimedia modules in this domain. Which institutions are really dedicating their efforts in training authors and designers in this area of CBTs? Television devices and broadcast organisations offered since year 60s' a first support for Distance Learning. New media, New Information and Communication Technologies (NICT allowed several public and private organisations to start Distance Learning projects. As usual some of them met their training objectives, other of them failed. Did their really failed? Currently, nobody has the right answer. Today, we do not have enough efficient tools allowing us to evaluate trainees' acquisition in a short term view. Training evaluation needs more than 10 to 20 years of elapsed time to bring reliable measures. Nevertheless, given the high investments already done in this area, we cannot wait until the final results of the pedagogical evaluation. A lot of analyses showed relevant issues which can be used as directions for CBTs authors and designers training. Warning - Our studies and the derived conclusions are mainly based on projects driven in the field. We additionally bring our several years experience in the training of movie film authors in the design of interactive multimedia products. Some of our examples are extracting from vocational training projects where we were involved in all development phases from the analysis of needs to the evaluation of the acquisition within the trainee's / employee job's. Obviously, we cannot bring and exhaustive approach in this domain where a lot of parameters are involved as frame for the CBT interactive multimedia modules authors' and designers' training.

  9. Geometric Computing Based on Computerized Descriptive Geometric

    Institute of Scientific and Technical Information of China (English)

    YU Hai-yan; HE Yuan-Jun

    2011-01-01

    Computer-aided Design (CAD), video games and other computer graphic related technology evolves substantial processing to geometric elements. A novel geometric computing method is proposed with the integration of descriptive geometry, math and computer algorithm. Firstly, geometric elements in general position are transformed to a special position in new coordinate system. Then a 3D problem is projected to new coordinate planes. Finally, according to 2D/3D correspondence principle in descriptive geometry, the solution is constructed computerized drawing process with ruler and compasses. In order to make this method a regular operation, a two-level pattern is established. Basic Layer is a set algebraic packaged function including about ten Primary Geometric Functions (PGF) and one projection transformation. In Application Layer, a proper coordinate is established and a sequence of PGFs is sought for to get the final results. Examples illustrate the advantages of our method on dimension reduction, regulatory and visual computing and robustness.

  10. Synthesis, characterization of 1,2,4-triazole Schiff base derived 3d-metal complexes: Induces cytotoxicity in HepG2, MCF-7 cell line, BSA binding fluorescence and DFT study

    Science.gov (United States)

    Tyagi, Prateek; Tyagi, Monika; Agrawal, Swati; Chandra, Sulekh; Ojha, Himanshu; Pathak, Mallika

    2017-01-01

    Two novel Schiff base ligands H2L1 and H2L2 have been synthesized by condensation reaction of amine derivative of 1,2,4-triazole moiety with 2-hydroxy-4-methoxybenzaldehyde. Co(II), Ni(II), Cu(II) and Zn(II) of the synthesized Schiff bases were prepared by using a molar ratio of ligand:metal as 1:1. The structure of the Schiff bases and synthesized metal complexes were established by 1H NMR, UV-Vis, IR, Mass spectrometry and molar conductivity. The thermal stability of the complexes was study by TGA. Fluorescence quenching mechanism of metal complexes 1-4 show that Zn(II) and Cu(II) complex binds more strongly to BSA. In DFT studies the geometries of Schiff bases and metal complexes were fully optimized with respect to the energy using the 6-31 + g(d,p) basis set. The spectral data shows that the ligands behaves as binegative tridentate. On the basis of the spectral studies, TGA and DFT data an octahedral geometry has been assigned for Co(II), Ni(II), square planar for Cu(II) and tetrahedral for Zn(II) complexes. The anticancer activity were screened against human breast cancer cell line (MCF-7) and human hepatocellular liver carcinoma cell line (Hep-G2). Result indicates that metal complexes shows increase cytotoxicity in proliferation to cell lines as compared to free ligand.

  11. An Emotional Agent Model Based on Granular Computing

    Directory of Open Access Journals (Sweden)

    Jun Hu

    2012-01-01

    Full Text Available Affective computing has a very important significance for fulfilling intelligent information processing and harmonious communication between human being and computers. A new model for emotional agent is proposed in this paper to make agent have the ability of handling emotions, based on the granular computing theory and the traditional BDI agent model. Firstly, a new emotion knowledge base based on granular computing for emotion expression is presented in the model. Secondly, a new emotional reasoning algorithm based on granular computing is proposed. Thirdly, a new emotional agent model based on granular computing is presented. Finally, based on the model, an emotional agent for patient assistant in hospital is realized, experiment results show that it is efficient to handle simple emotions.

  12. 基于DFT判决门限的OFDM信道估计算法%OFDM channel estimation based on DFT decision threshold method

    Institute of Scientific and Technical Information of China (English)

    李世平; 李鑫

    2011-01-01

    在正交频分复用系统中,为了提高信道估计算法的准确度和降低复杂度,首先对传统的离散傅里叶变换(DFT)信道估计算法进行了改进,通过引入判决门限,进一步消除信道噪声的影响,提高系统性能;然后与LS估计、SVD估计和DFT估计进行对比分析;最后通过Matlab软件进行仿真分析,结果表明了改进算法在基本不增加复杂度的前提下,提高了信道估计的准确度,进而提高整个系统的性能.%In Orthogonal Frequency Division Multiplexing (OFDM) systems, the key point is to improve accuracy and reduce complexity of channel estimation algorithm. First, the traditional Discrete Fourier Transform (DFT) channel estimation algorithm was improved. Furthermore, the impact of channel noise was eliminated through the introduction of the decision threshold, and system performance improved, then the improved channel estimation was compared with LS, SVD and DFT estimation. Finally, the Matlab simulation results show that the proposed algorithm can improve the accuracy of channel estimation without increasing the complexity, and then improve the performance of the whole system.Orthogonal Frequency Division Multiplexing (OFDM); Peak-to-Average Power Ratio (PAPR); Partial Transmit Sequence (PTS); m-sequence; pilot

  13. Measurement Based Quantum Computation on Fractal Lattices

    Directory of Open Access Journals (Sweden)

    Michal Hajdušek

    2010-06-01

    Full Text Available In this article we extend on work which establishes an analology between one-way quantum computation and thermodynamics to see how the former can be performed on fractal lattices. We find fractals lattices of arbitrary dimension greater than one which do all act as good resources for one-way quantum computation, and sets of fractal lattices with dimension greater than one all of which do not. The difference is put down to other topological factors such as ramification and connectivity. This work adds confidence to the analogy and highlights new features to what we require for universal resources for one-way quantum computation.

  14. Rigid Coumarins: a Complete DFT, TD-DFT and Non Linear Optical Property Study.

    Science.gov (United States)

    Lanke, Sandip K; Sekar, Nagaiyan

    2015-09-01

    The electronic structures and photophysical properties of rigid coumarin dyes have been studied by using quantum chemical methods. The ground-state geometries of these dyes were optimized using the Density Functional Theory (DFT) methods. The lowest singlet excited state was optimized using Time -Dependent Density Functional Theory [TD-B3LYP/6-31G(d)]. On the basis of ground- and excited-state geometries, the absorption and emission spectra have been calculated using the DFT and TD-DFT method. All the calculations were carried out in gas phase and in acetonitrile medium. The results show that the absorption maxima and fluorescence emission maxima calculated using the Time-Dependent Density Functional Theory is in good agreement with the available experimental results. To understand the Non- Linear Optical properties of coumarin dyes we computed dipole moment (μ), electronic polarizability (α), mean first hyperpolarizability (βo) and second hyperpolarizability (γ) using B3LYP density functional theory method in conjunction with 6-31G(d) basis set.

  15. A conceptual DFT approach towards analysing toxicity

    Indian Academy of Sciences (India)

    U Sarkar; D R Roy; P K Chattaraj; R Parthasarathi; J Padmanabhan; V Subramanian

    2005-09-01

    The applicability of DFT-based descriptors for the development of toxicological structure-activity relationships is assessed. Emphasis in the present study is on the quality of DFT-based descriptors for the development of toxicological QSARs and, more specifically, on the potential of the electrophilicity concept in predicting toxicity of benzidine derivatives and the series of polyaromatic hydrocarbons (PAH) expressed in terms of their biological activity data (50). First, two benzidine derivatives, which act as electron-donating agents in their interactions with biomolecules are considered. Overall toxicity in general and the most probable site of reactivity in particular are effectively described by the global and local electrophilicity parameters respectively. Interaction of two benzidine derivatives with nucleic acid (NA) bases/selected base pairs is determined using Parr’s charge transfer formula. The experimental biological activity data (50) for the family of PAH, namely polychlorinated dibenzofurans (PCDF), polyhalogenated dibenzo--dioxins (PHDD) and polychlorinated biphenyls (PCB) are taken as dependent variables and the HF energy (), along with DFT-based global and local descriptors, viz., electrophilicity index () and local electrophilic power (+) respectively are taken as independent variables. Fairly good correlation is obtained showing the significance of the selected descriptors in the QSAR on toxins that act as electron acceptors in the presence of biomolecules. Effects of population analysis schemes in the calculation of Fukui functions as well as that of solvation are probed. Similarly, some electron-donor aliphatic amines are studied in the present work. We see that global and local electrophilicities along with the HF energy are adequate in explaining the toxicity of several substances

  16. Experimental (X-ray, IR and UV-vis.) and DFT studies on cocrystallization of two tautomers of a novel Schiff base compound

    Science.gov (United States)

    Temel, Ersin; Alaşalvar, Can; Eserci, Hande; Ağar, Erbil

    2017-01-01

    In this study, the structure of 4-(((2-methyl-3-nitrophenyl)imino)methyl)benzene-1,2,3-triol was investigated with experimental (X-ray single crystal technique, UV-vis. and FT-IR spectroscopic techniques) and theoretical (DFT) methods. X-ray studies show that there are two independent molecules in asymmetric unit and coexist both keto-amin and enol-imine tautomeric forms. Theoretical studies were carried out in B3LYP with CAM-631G(d,p). The data obtained from calculation were compared with experimental data.

  17. Effectiveness of Computer-Based Education in Elementary Schools.

    Science.gov (United States)

    Kulik, James A.; And Others

    1985-01-01

    This metaanalysis of 32 comparative studies shows that computer-based education has generally had positive effects on the achievement of elementary school pupils. However, these effects are different for off-line computer managed instruction and interactive computer assisted instruction (CAI); interactive CAI produces greater increases in student…

  18. Design & implementation of distributed spatial computing node based on WPS

    Science.gov (United States)

    Liu, Liping; Li, Guoqing; Xie, Jibo

    2014-03-01

    Currently, the research work of SIG (Spatial Information Grid) technology mostly emphasizes on the spatial data sharing in grid environment, while the importance of spatial computing resources is ignored. In order to implement the sharing and cooperation of spatial computing resources in grid environment, this paper does a systematical research of the key technologies to construct Spatial Computing Node based on the WPS (Web Processing Service) specification by OGC (Open Geospatial Consortium). And a framework of Spatial Computing Node is designed according to the features of spatial computing resources. Finally, a prototype of Spatial Computing Node is implemented and the relevant verification work under the environment is completed.

  19. Efficient Tate pairing computation using double-base chains

    Institute of Scientific and Technical Information of China (English)

    ZHAO ChangAn; ZHANG FangGuo; HUANG JiWu

    2008-01-01

    Pairing-based cryptosystems have developed very fast in the last few years. The effi-ciencies of these cryptosystems depend on the computation of the bilinear pairings. In this paper, a new efficient algorithm based on double-base chains for computing the Tate pairing is proposed for odd characteristic p > 3. The inherent sparseness of double-base number system reduces the computational cost for computing the Tate pairing evidently. The new algorithm is 9% faster than the previous fastest method for the embedding degree k = 6.

  20. How Do DFT-DCP, DFT-NL, and DFT-D3 Compare for the Description of London-Dispersion Effects in Conformers and General Thermochemistry?

    Science.gov (United States)

    Goerigk, Lars

    2014-03-11

    The dispersion-core-potential corrected B3LYP-DCP method (Torres and DiLabio J. Phys. Chem. Lett. 2012, 3, 1738) is for the first time thoroughly assessed and compared with the B3LYP-NL (Hujo and Grimme J. Chem. Theory Comput. 2011, 7, 3866) and B3LYP-D3 (Grimme et al. J. Comput. Chem. 2011, 32, 1456) methods for a broad range of chemical problems that particularly shed light on intramolecular London-dispersion effects in conformers and general thermochemistry. The analysis is based on a compilation of 473 reference cases, the majority of which are taken from the GMTKN30 database (Goerigk and Grimme J. Chem. Theory Comput. 2010, 6, 107; 2011, 7, 291). The results confirm previous findings that B3LYP-DCP indeed predicts very good binding energies for noncovalently bound complexes, particularly with small basis sets. However, problems are identified for the description of intramolecular effects in some conformers and chemical reactions, for which B3LYP-DCP sometimes gives results similar or worse than uncorrected B3LYP. Surprisingly large errors for total atomization energies reveal an unwanted influence of the DCPs on the short-range electronic structure of the investigated systems. However, a recently modified carbon potential for B3LYP-DCP (DiLabio et al. Theor. Chem. Acc. 2013, 132, 1389) was additionally tested that seems to solve most of those problems and provides improved results. An overall comparison between all tested methods shows that B3LYP-NL is the most robust and accurate approach, closely followed by B3LYP-D3. This is also true when small basis sets of double-ζ quality are applied for which those methods have not been parametrized. However, binding energies of noncovalently bound complexes can be more strongly influenced by basis-set superposition-error effects than for B3LYP-DCP. Finally, it is noted that the DFT-D3 and DFT-NL schemes are readily applicable to a large range of chemical elements and they are therefore particularly recommended for

  1. A Compute Environment of ABC95 Array Computer Based on Multi-FPGA Chip

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    ABC95 array computer is a multi-function network's computer based on FPGA technology, The multi-function network supports processors conflict-free access data from memory and supports processors access data from processors based on enhanced MESH network.ABC95 instruction's system includes control instructions, scalar instructions, vectors instructions.Mostly net-work instructions are introduced.A programming environment of ABC95 array computer assemble language is designed.A programming environment of ABC95 array computer for VC++ is advanced.It includes load function of ABC95 array computer program and data, store function, run function and so on.Specially, The data type of ABC95 array computer conflict-free access is defined.The results show that these technologies can develop programmer of ABC95 array computer effectively.

  2. Computational anatomy based on whole body imaging basic principles of computer-assisted diagnosis and therapy

    CERN Document Server

    Masutani, Yoshitaka

    2017-01-01

    This book deals with computational anatomy, an emerging discipline recognized in medical science as a derivative of conventional anatomy. It is also a completely new research area on the boundaries of several sciences and technologies, such as medical imaging, computer vision, and applied mathematics. Computational Anatomy Based on Whole Body Imaging highlights the underlying principles, basic theories, and fundamental techniques in computational anatomy, which are derived from conventional anatomy, medical imaging, computer vision, and applied mathematics, in addition to various examples of applications in clinical data. The book will cover topics on the basics and applications of the new discipline. Drawing from areas in multidisciplinary fields, it provides comprehensive, integrated coverage of innovative approaches to computational anatomy. As well,Computational Anatomy Based on Whole Body Imaging serves as a valuable resource for researchers including graduate students in the field and a connection with ...

  3. Evaluation of computer-based ultrasonic inservice inspection systems

    Energy Technology Data Exchange (ETDEWEB)

    Harris, R.V. Jr.; Angel, L.J.; Doctor, S.R.; Park, W.R.; Schuster, G.J.; Taylor, T.T. [Pacific Northwest Lab., Richland, WA (United States)

    1994-03-01

    This report presents the principles, practices, terminology, and technology of computer-based ultrasonic testing for inservice inspection (UT/ISI) of nuclear power plants, with extensive use of drawings, diagrams, and LTT images. The presentation is technical but assumes limited specific knowledge of ultrasonics or computers. The report is divided into 9 sections covering conventional LTT, computer-based LTT, and evaluation methodology. Conventional LTT topics include coordinate axes, scanning, instrument operation, RF and video signals, and A-, B-, and C-scans. Computer-based topics include sampling, digitization, signal analysis, image presentation, SAFI, ultrasonic holography, transducer arrays, and data interpretation. An evaluation methodology for computer-based LTT/ISI systems is presented, including questions, detailed procedures, and test block designs. Brief evaluations of several computer-based LTT/ISI systems are given; supplementary volumes will provide detailed evaluations of selected systems.

  4. Telemedicine Based on Mobile Devices and Mobile Cloud Computing

    Directory of Open Access Journals (Sweden)

    Lidong Wang

    2014-04-01

    Full Text Available Mobile devices such as smartphones and tablets support kinds of mobile computing and services. They can access to the cloud or offload the computation-intensive part to the cloud computing resources. Mobile cloud computing (MCC integrates the cloud computing into the mobile environment, which extends mobile devices’ battery lifetime, improves their data storage capacity and processing power, and improves their reliability and information security. In this paper, the applications of smartphones in telemedicine and MCC-based telemedicine were presented. Issues on the information security of smartphones and tablets, challenges of smartphones in telemedicine and challenges of MCC-based telemedicine were also introduced.

  5. Computation of the Isotropic Hyperfine Coupling Constant: Efficiency and Insights from a New Approach Based on Wave Function Theory.

    Science.gov (United States)

    Giner, Emmanuel; Tenti, Lorenzo; Angeli, Celestino; Ferré, Nicolas

    2017-02-14

    The present paper reports an original computational strategy for the computation of the isotropic hyperfine coupling constants (hcc). The algorithm proposed here is based on an approach recently introduced by some of the authors, namely, the first-order breathing orbital self-consistent field (FOBO-SCF). The approach is an almost parameter-free wave function method capable to accurately treat the spin delocalization together with the spin polarization effects while staying in a restricted formalism and avoiding spin contamination. The efficiency of the method is tested on a series of small radicals, among which four nitroxide radicals and the comparison with high-level ab initio methods show very encouraging results. On the basis of these results, the method is then applied to compute the hcc of a challenging system, namely, the DEPMPO-OOH radical in various conformations. The reference values obtained on such a large system allows us to validate a cheap computational method based on density functional theory (DFT). Another interesting feature of the model applied here is that it allows for the rationalization of the results according to a relatively simple scheme based on a two-step mechanism. More precisely, the results are analyzed in terms of two separated contributions: first the spin delocalization and then the spin polarization.

  6. Interaction potential for water dimer from symmetry-adapted perturbation theory based on density functional description of monomers

    NARCIS (Netherlands)

    Bukowski, R.; Szalewicz, K.; Groenenboom, G.C.; Avoird, A. van der

    2006-01-01

    A new six-dimensional interaction potential for the water dimer has been obtained by fitting interaction energies computed at 2510 geometries using a variant of symmetry-adapted perturbation theory (SAPT) based on density functional theory (DFT) description of monomers, referred to as SAPT(DFT). The

  7. Evolving technologies for Space Station Freedom computer-based workstations

    Science.gov (United States)

    Jensen, Dean G.; Rudisill, Marianne

    1990-01-01

    Viewgraphs on evolving technologies for Space Station Freedom computer-based workstations are presented. The human-computer computer software environment modules are described. The following topics are addressed: command and control workstation concept; cupola workstation concept; Japanese experiment module RMS workstation concept; remote devices controlled from workstations; orbital maneuvering vehicle free flyer; remote manipulator system; Japanese experiment module exposed facility; Japanese experiment module small fine arm; flight telerobotic servicer; human-computer interaction; and workstation/robotics related activities.

  8. Surface Defect Inspection of TFT-LCD Panels Based on 2D DFT%基于二维DFT的TFT-LCD平板表面缺陷检测

    Institute of Scientific and Technical Information of China (English)

    张腾达; 卢荣胜; 张书真

    2016-01-01

    In order to detect the surface defects of TFT-LCD panel, an Automated Optical Inspection (AOI) experimental system was built and a defect detection algorithm was proposed based on two-dimensional (2D) DFT. The lines associated with high-energy frequency components in the spectrum that represented linear texture could be detected by Hough Transform (HT), and the corresponding neighborhood of high-energy frequency components were set to zero, and then a spatial domain image was reconstructed using the two-dimensional IDFT to remove the background of directional linear texture. Moreover, a simple threshold algorithm was used to discriminate the defects from the background. When calculating the slope-angle of high-energy frequency components in Fourier domain, two key points of how to select the high-energy threshold in frequency domain and how to extract the peaks from the angle histogram automatically were solved by using mathematical statistics. To preserve the defect, whose direction is near to directional-textures in the reconstructed image, all frequency components lying within a small annulus with the DC as the center in Fourier domain must be retained. The experiments on a variety of surface defects such as fibers, stains and scratches in TFT - LCD panel testified the effectiveness and robustness of the proposed method.%为了检测TFT-LCD平板表面缺陷,搭建了自动光学检测(AOI)实验系统,提出了一种基于二维DFT的缺陷检测算法。通过霍夫变换(HT)检测到代表线状纹理的高能量频域直线,将位于直线邻域内的频率成分置0,再经过二维 IDFT 进行空间域图像重构,来移除方向性线状纹理背景,最后经过简单的阈值算法将缺陷从背景中提取出来。在对高能量频域直线的斜角计算时,利用数学统计解决了如何自动选取频域中高能量阈值以及如何从斜角直方图中自动提取各个峰值点这两个关键问题。在重构图像时,在以

  9. Structure, electronic properties and vibrational spectra of (MgF2)n clusters through a combination of genetic algorithm and DFT-based approach

    Science.gov (United States)

    Ganguly Neogi, Soumya; Chaudhury, Pinaki

    2015-12-01

    In this article, we look at the option of using a stochastic optimisation technique, namely genetic algorithm (GA) in association with density functional theory (DFT) to find out the global minimum structures of (MgF2)n clusters with the range of n being between 2 and 10. To confirm whether the structures are indeed the acceptable ones, we go on to evaluate several properties like IR spectroscopic modes, vertical excitation energy, cluster formation energy, vertical ionisation potential and the HOMO-LUMO gap. We stress on the fact that an initial estimation of structure using GA, on two empirical potentials (with and without inclusion of polarisation), leads to a very quick convergence to structures which are quite close to the structures obtained from quantum chemical calculations done from the outset, such as using a DFT calculation. The general structural trend of these systems to form three-dimensional networks is also clear from our study. The lowest energy isomers of these clusters show preference for four-membered Mg2F2 and six-membered Mg3F3 rings. In the IR spectra of (MgF2)n clusters, a blueshift of the Mg-F symmetric stretch and a redshift of asymmetric Mg-F stretching as n increases are obtained.

  10. A new experimental and theoretical investigation on the structures of aminoethyl phosphonic acid in aqueous medium based on the vibrational spectra and DFT calculations

    Science.gov (United States)

    Roldán, María L.; Ledesma, Ana E.; Raschi, Ana B.; Castillo, María V.; Romano, Elida; Brandán, Silvia A.

    2013-06-01

    A new study on the structural and vibrational properties of the aminoethylphosphonic acid was performed in aqueous solution phase by using the self-consistent reaction field (SCRF) method. We have studied and characterized it by infrared and Raman spectroscopies in solid and aqueous solution phases. The Density Functional Theory (DFT) method with Pople's basis set show that three stable zwitterions for the title molecule have been theoretically determined in aqueous solution and that probably they are present in it medium. Here, the solvent effects were studied by means of the self-consistent reaction field (SCRF) method with the polarized continuum model (PCM). The harmonic vibrational frequencies for the optimized geometries of the three zwitterions were calculated at the B3LYP/6-31G∗ level of the theory. A complete assignment of the IR and Raman spectra of the compound in aqueous solution was performed combining the DFT calculations with Pulay's Scaled Quantum Mechanics Force Field (SQMFF) methodology in order to fit the theoretical frequency values to the experimental ones. Moreover, Natural Bond Orbital (NBO) and topological properties calculations were performed to analyze the energies and geometrical parameters of its three zwitterions in aqueous medium as well as the magnitude of the intramolecular interactions. The bond orders, atomic charges, solvation energies, dipole moments, molecular electrostatic potentials and force constants parameters calculated for zwitterions in aqueous solution, may be used to gain chemical and vibrational insights into related compounds.

  11. Influence of xc functional on thermal-elastic properties of Ceria: A DFT-based Debye-Grüneisen model approach

    Science.gov (United States)

    Lee, Ji-Hwan; Tak, Youngjoo; Lee, Taehun; Soon, Aloysius

    Ceria (CeO2-x) is widely studied as a choice electrolyte material for intermediate-temperature (~ 800 K) solid oxide fuel cells. At this temperature, maintaining its chemical stability and thermal-mechanical integrity of this oxide are of utmost importance. To understand their thermal-elastic properties, we firstly test the influence of various approximations to the density-functional theory (DFT) xc functionals on specific thermal-elastic properties of both CeO2 and Ce2O3. Namely, we consider the local-density approximation (LDA), the generalized gradient approximation (GGA-PBE) with and without additional Hubbard U as applied to the 4 f electron of Ce, as well as the recently popularized hybrid functional due to Heyd-Scuseria-Ernzehof (HSE06). Next, we then couple this to a volume-dependent Debye-Grüneisen model to determine the thermodynamic quantities of ceria at arbitrary temperatures. We find an explicit description of the strong correlation (e.g. via the DFT + U and hybrid functional approach) is necessary to have a good agreement with experimental values, in contrast to the mean-field treatment in standard xc approximations (such as LDA or GGA-PBE). We acknowledge support from Samsung Research Funding Center of Samsung Electronics (SRFC-MA1501-03).

  12. A DNA based model for addition computation

    Institute of Scientific and Technical Information of China (English)

    GAO Lin; YANG Xiao; LIU Wenbin; XU Jin

    2004-01-01

    Much effort has been made to solve computing problems by using DNA-an organic simulating method, which in some cases is preferable to the current electronic computer. However, No one at present has proposed an effective and applicable method to solve addition problem with molecular algorithm due to the difficulty in solving the carry problem which can be easily solved by hardware of an electronic computer. In this article, we solved this problem by employing two kinds of DNA strings, one is called result and operation string while the other is named carrier. The result and operation string contains some carry information by its own and denotes the ultimate result while the carrier is just for carrying use. The significance of this algorithm is the original code, the fairly easy steps to follow and the feasibility under current molecular biological technology.

  13. Confidential benchmarking based on multiparty computation

    DEFF Research Database (Denmark)

    Damgård, Ivan Bjerre; Damgård, Kasper Lyneborg; Nielsen, Kurt

    We report on the design and implementation of a system that uses multiparty computation to enable banks to benchmark their customers' confidential performance data against a large representative set of confidential performance data from a consultancy house. The system ensures that both the banks......' and the consultancy house's data stays confidential, the banks as clients learn nothing but the computed benchmarking score. In the concrete business application, the developed prototype help Danish banks to find the most efficient customers among a large and challenging group of agricultural customers with too much...

  14. A Web-based Distributed Voluntary Computing Platform for Large Scale Hydrological Computations

    Science.gov (United States)

    Demir, I.; Agliamzanov, R.

    2014-12-01

    Distributed volunteer computing can enable researchers and scientist to form large parallel computing environments to utilize the computing power of the millions of computers on the Internet, and use them towards running large scale environmental simulations and models to serve the common good of local communities and the world. Recent developments in web technologies and standards allow client-side scripting languages to run at speeds close to native application, and utilize the power of Graphics Processing Units (GPU). Using a client-side scripting language like JavaScript, we have developed an open distributed computing framework that makes it easy for researchers to write their own hydrologic models, and run them on volunteer computers. Users will easily enable their websites for visitors to volunteer sharing their computer resources to contribute running advanced hydrological models and simulations. Using a web-based system allows users to start volunteering their computational resources within seconds without installing any software. The framework distributes the model simulation to thousands of nodes in small spatial and computational sizes. A relational database system is utilized for managing data connections and queue management for the distributed computing nodes. In this paper, we present a web-based distributed volunteer computing platform to enable large scale hydrological simulations and model runs in an open and integrated environment.

  15. Computer-based speech therapy for childhood speech sound disorders.

    Science.gov (United States)

    Furlong, Lisa; Erickson, Shane; Morris, Meg E

    2017-07-01

    With the current worldwide workforce shortage of Speech-Language Pathologists, new and innovative ways of delivering therapy to children with speech sound disorders are needed. Computer-based speech therapy may be an effective and viable means of addressing service access issues for children with speech sound disorders. To evaluate the efficacy of computer-based speech therapy programs for children with speech sound disorders. Studies reporting the efficacy of computer-based speech therapy programs were identified via a systematic, computerised database search. Key study characteristics, results, main findings and details of computer-based speech therapy programs were extracted. The methodological quality was evaluated using a structured critical appraisal tool. 14 studies were identified and a total of 11 computer-based speech therapy programs were evaluated. The results showed that computer-based speech therapy is associated with positive clinical changes for some children with speech sound disorders. There is a need for collaborative research between computer engineers and clinicians, particularly during the design and development of computer-based speech therapy programs. Evaluation using rigorous experimental designs is required to understand the benefits of computer-based speech therapy. The reader will be able to 1) discuss how computerbased speech therapy has the potential to improve service access for children with speech sound disorders, 2) explain the ways in which computer-based speech therapy programs may enhance traditional tabletop therapy and 3) compare the features of computer-based speech therapy programs designed for different client populations. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Computer-based studies on enzyme catalysis

    NARCIS (Netherlands)

    Ridder, L.

    2000-01-01

    Theoretical simulations are becoming increasingly important for our understanding of how enzymes work. The aim of the research presented in this thesis is to contribute to this development by applying various computational methods to three enzymes of theβ-ketoadipate pathway, and to validate the mod

  17. Cloud Computing Based E-Learning System

    Science.gov (United States)

    Al-Zoube, Mohammed; El-Seoud, Samir Abou; Wyne, Mudasser F.

    2010-01-01

    Cloud computing technologies although in their early stages, have managed to change the way applications are going to be developed and accessed. These technologies are aimed at running applications as services over the internet on a flexible infrastructure. Microsoft office applications, such as word processing, excel spreadsheet, access database…

  18. Computer-Based Instruction in Elementary Hindi.

    Science.gov (United States)

    Kachru, Yamuna; And Others

    1981-01-01

    Computer-assisted instruction for Hindi courses at the University of Illinois is described in relation to the technical aspects of programming Hindi on the PLATO system and the curriculum components. The program focuses on review of the materials already covered in class and building understanding of a number of grammatical constructions by using…

  19. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    Mourrain, B.; Lasserre, J.B.; Laurent, M.; Rostalski, P.; Trebuchet, P.

    2011-01-01

    In this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is nte. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and semi-denite programming.

  20. Moment matrices, border bases and radical computation

    NARCIS (Netherlands)

    Mourrain, B.; Lasserre, J.B.; Laurent, M.; Rostalski, P.; Trebuchet, P.

    2013-01-01

    In this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is nte. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and semi-denite programming.

  1. Efficient GPU-based skyline computation

    DEFF Research Database (Denmark)

    Bøgh, Kenneth Sejdenfaden; Assent, Ira; Magnani, Matteo

    2013-01-01

    The skyline operator for multi-criteria search returns the most interesting points of a data set with respect to any monotone preference function. Existing work has almost exclusively focused on efficiently computing skylines on one or more CPUs, ignoring the high parallelism possible in GPUs. In...

  2. Cloud Computing Based E-Learning System

    Science.gov (United States)

    Al-Zoube, Mohammed; El-Seoud, Samir Abou; Wyne, Mudasser F.

    2010-01-01

    Cloud computing technologies although in their early stages, have managed to change the way applications are going to be developed and accessed. These technologies are aimed at running applications as services over the internet on a flexible infrastructure. Microsoft office applications, such as word processing, excel spreadsheet, access database…

  3. An Overview of Innovative Computer-Based Testing

    NARCIS (Netherlands)

    Klerk, Sebastiaan; Eggen, Theodorus Johannes Hendrikus Maria; Veldkamp, Bernard P.

    2012-01-01

    Driven by the technological revolution, computer-based testing (CBT) has witnessed an explosive rise the last decades, in both psychological and educational assessment. Many paper-and-pencil tests now have a computer-based equivalent. Innovations in CBT are almost innumerable, and innovative and new

  4. Computer-Based Integrated Learning Systems: Research and Theory.

    Science.gov (United States)

    Hativa, Nira, Ed.; Becker, Henry Jay, Ed.

    1994-01-01

    The eight chapters of this theme issue discuss recent research and theory concerning computer-based integrated learning systems. Following an introduction about their theoretical background and current use in schools, the effects of using computer-based integrated learning systems in the elementary school classroom are considered. (SLD)

  5. Computer-Based Science Education. CERL Report X-37.

    Science.gov (United States)

    Bitzer, Donald L.; And Others

    The PLATO IV system of computer-based education developed at the University of Illinois is discussed. A brief description of the PLATO system operation is given, and lesson examples are provided for the areas of biology, geometry, chemistry, and physics. Basic problems in the field of computer-based education are discussed, along with possible…

  6. Computer-Based Instruction in Basic Medical Science Education.

    Science.gov (United States)

    Marion, Roger; And Others

    1982-01-01

    Literature on computer-based instruction shows student performance improves with this method, although students spend less time studying. It is recommended that future research be designed to better detect the influence of computer-based instruction and that greater attention be given to methodological issues like test construction and research…

  7. Spectroscopy (FT-IR, FT-Raman), hydrogen bonding, electrostatic potential and HOMO-LUMO analysis of tioxolone based on DFT calculations

    Science.gov (United States)

    Tao, Yaping; Li, Xiaofeng; Han, Ligang; Zhang, Weiying; Liu, Zhaojun

    2016-10-01

    Tioxolone possess antipsoriatic and antibacterial properties. Therefore, it has been used in treating various skin and scalp disorders for many years. Spectroscopic analysis of tioxolone was presented by using density functional theory (DFT) calculations and experiments (FT-IR, FT-Raman and UV-Vis). Molecular geometry and vibrational wavenumbers of tioxolone were investigated by using B3LYP method with aug-cc-pVTZ basis set. A complete vibrational spectra was made to analyze the potential energy distributions (PED). In addition, analysis of frontier molecular orbitals, electrostatic potential (ESP) and thermodynamic properties (heat capacity, entropy, enthalpy and Gibbs free energy) was presented with the same basis-set. Furthermore, the nature of molecular association through hydrogen bonding were discussed using atoms in molecules (AIM) and reduced density gradient (RDG) methods.

  8. Synthesis, photovoltaic performances and TD-DFT modeling of push-pull diacetylide platinum complexes in TiO2 based dye-sensitized solar cells.

    Science.gov (United States)

    Gauthier, Sébastien; Caro, Bertrand; Robin-Le Guen, Françoise; Bhuvanesh, Nattamai; Gladysz, John A; Wojcik, Laurianne; Le Poul, Nicolas; Planchat, Aurélien; Pellegrin, Yann; Blart, Errol; Jacquemin, Denis; Odobel, Fabrice

    2014-08-07

    In this joint experimental-theoretical work, we present the synthesis and optical and electrochemical characterization of five new bis-acetylide platinum complex dyes end capped with diphenylpyranylidene moieties, as well as their performances in dye-sensitized solar cells (DSCs). Theoretical calculations relying on Time-Dependent Density Functional Theory (TD-DFT) and a range-separated hybrid show a very good match with experimental data and allow us to quantify the charge-transfer character of each compound. The photoconversion efficiency obtained reaches 4.7% for 8e (see TOC Graphic) with the tri-thiophene segment, which is among the highest efficiencies reported for platinum complexes in DSCs.

  9. Chaos-based Cryptography for Cloud Computing

    OpenAIRE

    Tobin, Paul; Tobin, Lee; McKeever, Michael; Blackledge, Jonathan

    2017-01-01

    Cloud computing and poor security issues have quadrupled over the last six years and with the alleged presence of backdoors in common encryption ciphers, has created a need for personalising the encryption process by the client. In 2007, two Microsoft employees gave a presentation ``On the Possibility of a backdoor in the NIST SP800-90 Dual Elliptic Curve Pseudo Random Number Generators'' and was linked in 2013 by the New York Times with notes leaked by Edward Snowden. This confirmed backdoor...

  10. Multichromophoric bimetallic Ru(II) terpyridine complexes based on pyrenyl-bis-phenylimidazole spacer: synthesis, photophysics, spectroelectrochemistry, and TD-DFT calculations.

    Science.gov (United States)

    Karmakar, Srikanta; Maity, Dinesh; Mardanya, Sourav; Baitalik, Sujoy

    2014-11-17

    A symmetrical bridging ligand, 5,11-bis(4-([2,2':6',2″-terpyridine]-4'-yl)phenyl)-4,12-dihydropyreno[4,5-d:9,10-d']diimidazole (tpy-H2PhImzPy-tpy), containing terpyridyl coordinating units connected via a pyrenyl-bis-phenylimidazole spacer have been designed to synthesize a new class of light harvesting bimetallic Ru(II) complexes. The electronic properties of this complexes can be fine-tuned by varying tridentate terminal ligands. Full characterization of the compounds has been done with the help of (1)H NMR spectroscopy, high-resolution mass spectrometry, and elemental analysis. Geometry optimization of the complexes was also carried out with density functional theory (DFT). Electronic absorption spectra exhibit a number of very intense π-π* and n-π* transitions in the UV and moderately intense MLCT and ILCT transitions in the visible region. Interestingly, the present bimetallic complexes exhibit moderately strong luminescence in the range between 657 and 703 nm and lifetimes (long component) between 5.8 and 67.0 ns at room temperature showing the dependence of the emission characteristics upon the type of terminal ligand and solvent. Detailed temperature-dependent emission measurements showed that an overall enhancement of photoluminescence intensity and lifetime occur in all three cases upon lowering of temperature. The redox behavior of the compounds is characterized by a single reversible anodic wave corresponding to two closely spaced one-electron processes. The appearance of intervalence charge transfer transition (IVCT) bands in the NIR region on electrochemical generation of Ru(II)Ru(II)/Ru(II)Ru(III) species indicates the presence of substantial electronic communication among the two ruthenium centers in the bimetallic complexes. DFT and TDDFT calculations were also done for better understanding of the absorption and emission spectral characteristics of the complexes.

  11. Computational prediction and experimental selectivity coefficients for hydroxyzine and cetirizine molecularly imprinted polymer based potentiometric sensors

    Energy Technology Data Exchange (ETDEWEB)

    Azimi, Abolfazl; Javanbakht, Mehran, E-mail: mehranjavanbakht@gmail.com

    2014-02-17

    Graphical abstract: -- Highlights: •Possible configurations template/monomer complexes were designed and optimized. •Effect of the electrostatic force on the selectivity of MIPs was investigated. •A correlation between selectivity of sensors and a charge distribution was obtained. -- Abstract: In spite of the increasing usages number of molecularly imprinted polymers (MIPs) in many scientific applications, the theoretical aspects of participating intra molecular forces are not fully understood. This work investigates effects of the electrostatic force, the Mulliken charge and the role of cavity's backbone atoms on the selectivity of MIPs. Moreover, charge distribution, which is a computational parameter, was proposed for the prediction of the selectivity coefficients of MIP-based sensors. In the computational approaches and experimental study, methacrylic acid (MAA) was chosen as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the cross linker for hydroxyzine and cetirizine imprinted polymers. Ab initio, DFT B3LYP method was carried out on molecular optimization. With regard to results obtained from molecules optimization and hydrogen bonding properties, possible configurations of 1:n (n ≤ 5) template/monomer complexes were designed and optimized. The binding energy for each complex in gas phase was calculated. Depending on the most stable configuration, hydroxyzine and cetirizine imprinted polymer models were designed. The calculations including the porogen were also investigated. The theoretical charge distributions for the template and some potential interfering molecules were calculated. The results showed a correlation between the selectivity coefficients and the theoretical charge distributions. The results surprisingly show that charge distribution based model was able to predict the selectivity coefficients of MIP based potentiometric sensors.

  12. Parallel CFD design on network-based computer

    Science.gov (United States)

    Cheung, Samson

    1995-01-01

    Combining multiple engineering workstations into a network-based heterogeneous parallel computer allows application of aerodynamic optimization with advanced computational fluid dynamics codes, which can be computationally expensive on mainframe supercomputers. This paper introduces a nonlinear quasi-Newton optimizer designed for this network-based heterogeneous parallel computing environment utilizing a software called Parallel Virtual Machine. This paper will introduce the methodology behind coupling a Parabolized Navier-Stokes flow solver to the nonlinear optimizer. This parallel optimization package is applied to reduce the wave drag of a body of revolution and a wing/body configuration with results of 5% to 6% drag reduction.

  13. Inquiry-Based Learning Case Studies for Computing and Computing Forensic Students

    Science.gov (United States)

    Campbell, Jackie

    2012-01-01

    Purpose: The purpose of this paper is to describe and discuss the use of specifically-developed, inquiry-based learning materials for Computing and Forensic Computing students. Small applications have been developed which require investigation in order to de-bug code, analyse data issues and discover "illegal" behaviour. The applications…

  14. Interactive Computer-Assisted Instruction in Acid-Base Physiology for Mobile Computer Platforms

    Science.gov (United States)

    Longmuir, Kenneth J.

    2014-01-01

    In this project, the traditional lecture hall presentation of acid-base physiology in the first-year medical school curriculum was replaced by interactive, computer-assisted instruction designed primarily for the iPad and other mobile computer platforms. Three learning modules were developed, each with ~20 screens of information, on the subjects…

  15. Computer Assisted Project-Based Instruction: The Effects on Science Achievement, Computer Achievement and Portfolio Assessment

    Science.gov (United States)

    Erdogan, Yavuz; Dede, Dinçer

    2015-01-01

    The purpose of this study is to compare the effects of computer assisted project-based instruction on learners' achievement in a science and technology course, in a computer course and in portfolio development. With this aim in mind, a quasi-experimental design was used and a sample of 70 seventh grade secondary school students from Org. Esref…

  16. Learning with Computer-Based Learning Environments: A Literature Review of Computer Self-Efficacy

    Science.gov (United States)

    Moos, Daniel C.; Azevedo, Roger

    2009-01-01

    Although computer-based learning environments (CBLEs) are becoming more prevalent in the classroom, empirical research has demonstrated that some students have difficulty learning with these environments. The motivation construct of computer-self efficacy plays an integral role in learning with CBLEs. This literature review synthesizes research…

  17. Interactive Computer-Assisted Instruction in Acid-Base Physiology for Mobile Computer Platforms

    Science.gov (United States)

    Longmuir, Kenneth J.

    2014-01-01

    In this project, the traditional lecture hall presentation of acid-base physiology in the first-year medical school curriculum was replaced by interactive, computer-assisted instruction designed primarily for the iPad and other mobile computer platforms. Three learning modules were developed, each with ~20 screens of information, on the subjects…

  18. Activity-based computing: computational management of activities reflecting human intention

    DEFF Research Database (Denmark)

    Bardram, Jakob E; Jeuris, Steven; Houben, Steven

    2015-01-01

    paradigm that has been applied in personal information management applications as well as in ubiquitous, multidevice, and interactive surface computing. ABC has emerged as a response to the traditional application- and file-centered computing paradigm, which is oblivious to a notion of a user’s activity...... context spanning heterogeneous devices, multiple applications, services, and information sources. In this article, we present ABC as an approach to contextualize information, and present our research into designing activity-centric computing technologies.......An important research topic in artificial intelligence is automatic sensing and inferencing of contextual information, which is used to build computer models of the user’s activity. One approach to build such activity-aware systems is the notion of activity-based computing (ABC). ABC is a computing...

  19. Activity-based computing: computational management of activities reflecting human intention

    DEFF Research Database (Denmark)

    Bardram, Jakob E; Jeuris, Steven; Houben, Steven

    2015-01-01

    An important research topic in artificial intelligence is automatic sensing and inferencing of contextual information, which is used to build computer models of the user’s activity. One approach to build such activity-aware systems is the notion of activity-based computing (ABC). ABC is a computing...... paradigm that has been applied in personal information management applications as well as in ubiquitous, multidevice, and interactive surface computing. ABC has emerged as a response to the traditional application- and file-centered computing paradigm, which is oblivious to a notion of a user’s activity...... context spanning heterogeneous devices, multiple applications, services, and information sources. In this article, we present ABC as an approach to contextualize information, and present our research into designing activity-centric computing technologies....

  20. A Logistics Distribution Plan Based on Cloud Computing

    OpenAIRE

    2013-01-01

    Aiming at the problems of lowing informatization level and degree of specialization, high consumption and low efficiency in logistics and distribution industry, this paper analyzes the characteristics of cloud computing and the actual needs of enterprise logistics. On this basis, depth study of the logistics and distribution needs of the cloud computing architecture, depth study of the cloud computing architecture in the logistics and distribution needs, and then propose a cloud-based modern ...

  1. DFT study with inclusion of the Grimme potential on anatase TiO2: structure, electronic, and vibrational analyses.

    Science.gov (United States)

    Albuquerque, Anderson R; Garzim, Marcos L; Santos, Iêda M G dos; Longo, Valeria; Longo, Elson; Sambrano, Julio R

    2012-11-29

    Periodic DFT/B3LYP calculations for TiO(2) anatase bulk were carried out including semiempirical dispersive interactions (DFT-D2) to pure Khon-Sham DFT energy. From this standard methodology, van der Waals (vdW) radii were optimized to 1.4214 Å for titanium and 1.3420 Å for oxygen centers in order to achieve a better structural description. The results from this approach (here named DFT/B3LYP-D*) showed a better description for lattice constants, vibrational IR and Raman, energy band gaps, and bulk modulus than default DFT/B3LYP and DFT/B3LYP-D. The dispersion correction showed more reliable results and was necessary to achieve a good agreement with reported single crystal results, without new formalism or additional computational cost.

  2. Physical Optics Based Computational Imaging Systems

    Science.gov (United States)

    Olivas, Stephen Joseph

    There is an ongoing demand on behalf of the consumer, medical and military industries to make lighter weight, higher resolution, wider field-of-view and extended depth-of-focus cameras. This leads to design trade-offs between performance and cost, be it size, weight, power, or expense. This has brought attention to finding new ways to extend the design space while adhering to cost constraints. Extending the functionality of an imager in order to achieve extraordinary performance is a common theme of computational imaging, a field of study which uses additional hardware along with tailored algorithms to formulate and solve inverse problems in imaging. This dissertation details four specific systems within this emerging field: a Fiber Bundle Relayed Imaging System, an Extended Depth-of-Focus Imaging System, a Platform Motion Blur Image Restoration System, and a Compressive Imaging System. The Fiber Bundle Relayed Imaging System is part of a larger project, where the work presented in this thesis was to use image processing techniques to mitigate problems inherent to fiber bundle image relay and then, form high-resolution wide field-of-view panoramas captured from multiple sensors within a custom state-of-the-art imager. The Extended Depth-of-Focus System goals were to characterize the angular and depth dependence of the PSF of a focal swept imager in order to increase the acceptably focused imaged scene depth. The goal of the Platform Motion Blur Image Restoration System was to build a system that can capture a high signal-to-noise ratio (SNR), long-exposure image which is inherently blurred while at the same time capturing motion data using additional optical sensors in order to deblur the degraded images. Lastly, the objective of the Compressive Imager was to design and build a system functionally similar to the Single Pixel Camera and use it to test new sampling methods for image generation and to characterize it against a traditional camera. These computational

  3. Newer mixed ligand Schiff base complexes from aquo-N-(2‧-hydroxy acetophenone) glycinatocopper(II) as synthon: DFT, antimicrobial activity and molecular docking study

    Science.gov (United States)

    Pramanik, Harun A. R.; Das, Dharitri; Paul, Pradip C.; Mondal, Paritosh; Bhattacharjee, Chira R.

    2014-02-01

    Synthesis of a series of newer mixed ligand copper(II) complexes of aminoacid Schiff base of the type [CuL(X)] (L = N-(2‧-hydroxy acetophenone) glycinate, X = imidazole (im) 2, benzimidazole (benz) 3, pyridine (py) 4, hydrazine (hz) 5,8-hydroxyquinoline (8-hq) 6, pyrrolidine (pyrr) 7, piperidine (pip) 8, and nicotinamide (nic) 9) have been accomplished from the interaction of an aquated Schiff base complex, [CuL(H2O)]·H2O, 1 with some selected neutral nitrogen-donor ligands. The copper(II) Schiff base complex, [CuL(H2O)]·H2O, L = N-(2‧-hydroxy acetophenone) glycinate was synthesized from the reaction of glycine and 2‧ hydroxy acetophenone and copper(II) acetate. The compounds were characterised by elemental analysis, spectral, magnetic and thermal studies. The density functional theory calculations were performed using LANL2DZ and 6-311 G(d, p) basis sets with B3LYP correlation functional to ascertain the stable electronic structure, HOMO-LUMO energy gap, chemical hardness and dipole moment of the mixed ligand complexes. A distorted square planar geometry has been conjectured for the complexes. Antibacterial activities of the ligand and its metal complexes have been tested against selected gram-positive and gram-negative strains and correlated with computational docking scores.

  4. Activity-based computing for medical work in hospitals

    DEFF Research Database (Denmark)

    Bardram, Jakob Eyvind

    2009-01-01

    Studies have revealed that people organize and think of their work in terms of activities that are carried out in pursuit of some overall objective, often in collaboration with others. Nevertheless, modern computer systems are typically single-user oriented, that is, designed to support individual...... tasks such as word processing while sitting at a desk. This article presents the concept of Activity-Based Computing (ABC), which seeks to create computational support for human activities. The ABC approach has been designed to address activity-based computing support for clinical work in hospitals....... In a hospital, the challenges arising from the management of parallel activities and interruptions are amplified because multitasking is now combined with a high degree of mobility, collaboration, and urgency. The article presents the empirical and theoretical background for activity-based computing, its...

  5. Structural Investigation of Methanol {6-[(2-oxidopropyl)iminomethyl] phenolato} dioxidomolybdenum(VI) by X-Ray Crystallography and DFT Calculations

    OpenAIRE

    Iran SHEIKHSHOAIE; Yousef EBRAHIMIPOUR; Mahdiyeh SHEIKHSHOAEE

    2012-01-01

    This article presents the computational calculations of a cis-dioxomolybdenum(VI) complex by using density functional theory (DFT) with a DZP basis set (double zeta polarized basis set). The Schiff base 2-((E)-(2-hydroxypropylimino)methyl)-6-methoxyphenol was treated with MoO2(acac)2 in dry methanol to produce the mononuclear complex methanol{2-methoxy-6-[(2-oxidopropyl) iminomethyl]phenolato} dioxidomolybdenum(VI), whose structure has been solved and successfully refined in the monoclinic sp...

  6. An introduction to statistical computing a simulation-based approach

    CERN Document Server

    Voss, Jochen

    2014-01-01

    A comprehensive introduction to sampling-based methods in statistical computing The use of computers in mathematics and statistics has opened up a wide range of techniques for studying otherwise intractable problems.  Sampling-based simulation techniques are now an invaluable tool for exploring statistical models.  This book gives a comprehensive introduction to the exciting area of sampling-based methods. An Introduction to Statistical Computing introduces the classical topics of random number generation and Monte Carlo methods.  It also includes some advanced met

  7. Robust speech features representation based on computational auditory model

    Institute of Scientific and Technical Information of China (English)

    LU Xugang; JIA Chuan; DANG Jianwu

    2004-01-01

    A speech signal processing and features extracting method based on computational auditory model is proposed. The computational model is based on psychological, physiological knowledge and digital signal processing methods. In each stage of a hearing perception system, there is a corresponding computational model to simulate its function. Based on this model, speech features are extracted. In each stage, the features in different kinds of level are extracted. A further processing for primary auditory spectrum based on lateral inhibition is proposed to extract much more robust speech features. All these features can be regarded as the internal representations of speech stimulation in hearing system. The robust speech recognition experiments are conducted to test the robustness of the features. Results show that the representations based on the proposed computational auditory model are robust representations for speech signals.

  8. High Available COTS Based Computer for Space

    Science.gov (United States)

    Hartmann, J.; Magistrati, Giorgio

    2015-09-01

    The availability and reliability factors of a system are central requirements of a target application. From a simple fuel injection system used in cars up to a flight control system of an autonomous navigating spacecraft, each application defines its specific availability factor under the target application boundary conditions. Increasing quality requirements on data processing systems used in space flight applications calling for new architectures to fulfill the availability, reliability as well as the increase of the required data processing power. Contrary to the increased quality request simplification and use of COTS components to decrease costs while keeping the interface compatibility to currently used system standards are clear customer needs. Data processing system design is mostly dominated by strict fulfillment of the customer requirements and reuse of available computer systems were not always possible caused by obsolescence of EEE-Parts, insufficient IO capabilities or the fact that available data processing systems did not provide the required scalability and performance.

  9. Milestones Toward Majorana-Based Quantum Computing

    Science.gov (United States)

    Aasen, David; Hell, Michael; Mishmash, Ryan V.; Higginbotham, Andrew; Danon, Jeroen; Leijnse, Martin; Jespersen, Thomas S.; Folk, Joshua A.; Marcus, Charles M.; Flensberg, Karsten; Alicea, Jason

    2016-07-01

    We introduce a scheme for preparation, manipulation, and read out of Majorana zero modes in semiconducting wires with mesoscopic superconducting islands. Our approach synthesizes recent advances in materials growth with tools commonly used in quantum-dot experiments, including gate control of tunnel barriers and Coulomb effects, charge sensing, and charge pumping. We outline a sequence of milestones interpolating between zero-mode detection and quantum computing that includes (1) detection of fusion rules for non-Abelian anyons using either proximal charge sensors or pumped current, (2) validation of a prototype topological qubit, and (3) demonstration of non-Abelian statistics by braiding in a branched geometry. The first two milestones require only a single wire with two islands, and additionally enable sensitive measurements of the system's excitation gap, quasiparticle poisoning rates, residual Majorana zero-mode splittings, and topological-qubit coherence times. These pre-braiding experiments can be adapted to other manipulation and read out schemes as well.

  10. Computer-Based Interaction Analysis with DEGREE Revisited

    Science.gov (United States)

    Barros, B.; Verdejo, M. F.

    2016-01-01

    We review our research with "DEGREE" and analyse how our work has impacted the collaborative learning community since 2000. Our research is framed within the context of computer-based interaction analysis and the development of computer-supported collaborative learning (CSCL) tools. We identify some aspects of our work which have been…

  11. Touch-based Brain Computer Interfaces: State of the art

    NARCIS (Netherlands)

    Erp, J.B.F. van; Brouwer, A.M.

    2014-01-01

    Brain Computer Interfaces (BCIs) rely on the user's brain activity to control equipment or computer devices. Many BCIs are based on imagined movement (called active BCIs) or the fact that brain patterns differ in reaction to relevant or attended stimuli in comparison to irrelevant or unattended

  12. Individual Differences and Learning Performance in Computer-based Training

    Science.gov (United States)

    2011-02-01

    Navigation in hypermedia learning systems: experts vs. novices. Computers in Human Behavior , 22, 251–266. Chi, M. T. H., Glaser, R., & Rees, E...communication technologies on performance in a Web-based learning program. Computers in Human Behavior , 22(6), 962-970. Shivpuri, S., Schmitt, N., Oswald

  13. Computer-Based Self-Instructional Modules. Final Technical Report.

    Science.gov (United States)

    Weinstock, Harold

    Reported is a project involving seven chemists, six mathematicians, and six physicists in the production of computer-based, self-study modules for use in introductory college courses in chemistry, physics, and mathematics. These modules were designed to be used by students and instructors with little or no computer backgrounds, in institutions…

  14. Determination of Absolute Zero Using a Computer-Based Laboratory

    Science.gov (United States)

    Amrani, D.

    2007-01-01

    We present a simple computer-based laboratory experiment for evaluating absolute zero in degrees Celsius, which can be performed in college and undergraduate physical sciences laboratory courses. With a computer, absolute zero apparatus can help demonstrators or students to observe the relationship between temperature and pressure and use…

  15. Developing Educational Computer Animation Based on Human Personality Types

    Science.gov (United States)

    Musa, Sajid; Ziatdinov, Rushan; Sozcu, Omer Faruk; Griffiths, Carol

    2015-01-01

    Computer animation in the past decade has become one of the most noticeable features of technology-based learning environments. By its definition, it refers to simulated motion pictures showing movement of drawn objects, and is often defined as the art in movement. Its educational application known as educational computer animation is considered…

  16. Severe Neglect and Computer-based Home Training

    DEFF Research Database (Denmark)

    Wilms, Inge Linda

    2014-01-01

    . For this reason, this case study tests the possibility of using computer-based training in the rehabilitation efforts for a patient with severe neglect who had no previous skills in computer usage. The article describes the results of the training both in terms of neuro-psychological tests and the reading ability...

  17. Touch-based Brain Computer Interfaces: State of the art

    NARCIS (Netherlands)

    Erp, J.B.F. van; Brouwer, A.M.

    2014-01-01

    Brain Computer Interfaces (BCIs) rely on the user's brain activity to control equipment or computer devices. Many BCIs are based on imagined movement (called active BCIs) or the fact that brain patterns differ in reaction to relevant or attended stimuli in comparison to irrelevant or unattended stim

  18. First Principle Study of Uranium Nitrides UN and UN2 Using DFT and DFT + U

    Directory of Open Access Journals (Sweden)

    T. Zergoug

    2015-12-01

    Full Text Available First principle calculation based on density functional theory (DFT was used to evaluate some physical properties of Uranium Nitrides. Adsorption of oxygen O atom and O2 molecule on/in (001 surfaces of both Uranium monoNitride (UN and diNitride (UN2 was then studied and compared mutually. To treat the strong correlation effects caused by 5f Uranium valence electrons, Hubbard-U advanced (DFT + U approach was employed to correct the exchange correlation functional GGA and PBE which are based on generalized gradient approximation. The functional are developed for the Vienna Abinitio Simulation Package (VASP and were used with the projector-augmented wave (PAW pseudo potentials. The structural and elastic-mechanical UN and UN2 properties were calculated within DFT and DFT + U methods. Then, Potential Energy Surfaces (PES concepts which correspond to the interaction between O atom (respectively O2 molecule and (001 on-surfaces / sub-surfaces uranium nitrides for several positions were determined to identify favorable adsorption sites. Physical properties calculation results of UN or UN2 are in order of magnitude of other theoretical values and show an acceptable precision compared to experiments. Hubbard U value of the DFT + U formalism was optimized to achieve Antiferromagnetic (AFM UN configuration and was effective at U = 1.625 eV. Optimization of UN2 was accomplished to attain experimental cell parameter of 5.31 A° and was reached for U = 2.6 eV. According to our calculation results, O2 diffusion through UN(001 and UN2(001 clean surfaces have demonstrated dissociation of the molecule from a distance of approximately d = 1.5 Å. Favored on surface modes for O atom adsorption were found to be near the bridge site for UN(001 and UN2(001. The O incorporation through UN(001 surface was at the bridge site, nevertheless, for UN2, merging of O atom in the (001 surface bridge site was not allowed.

  19. DFT及多投影分析的织物纬斜检测方法研究%Fabric Skew Detection Method Based on DFT and Multi-projection Analysis

    Institute of Scientific and Technical Information of China (English)

    董燕; 朱永胜; 张晓慧

    2013-01-01

    For fabric image skew detection,the detection accuracy is vulnerable to light and fabric texture complexity.If process the image with a lot of redundant information directly,it needs a large amount of calculation,which is not suitable for real-time detection system.This paper proposed a novel method based on DFT and multi-projection analysis on the grounds of the DFT spectrum binarization and morphological filtering experiments.This method was used to remove the redundant information of DFT spectrum of the fabric image,rotate and projecte the spectrum in small step,then detected the skew angle of the fabric image based on the fact that a maximum of projection pixels appears in the center of the spectrum if the longitudinal centerline of the spectrum is vertical to the transverse axis.The experimental results show that this algorithm has high accuracy in detecting small amount of fabric skew and better adaptability of the fabric density.%研究织物图像纬斜准确检测的问题,检测精度易受光线及织物纹理复杂性的影响,如将存在着大量冗余信息的图像直接进行处理,计算量大,不适合用实时检测系统.在对织物的DFT谱进行二值化、形态学滤波等一系列实验的基础上,提出了一种基于DFT及多投影分析的纬斜量检测方法.方法将织物图像的DFT变换谱去除冗余信息,再以较小的步长进行旋转投影,根据频谱图的纵轴与横坐标垂直时在频谱图的中心位置会出现投影像素的最大值的原理,检测出织物图像的倾斜角度.实验结果证明该算法在对小角度的纬斜量检测时,具有较高的精度,且对织物的疏密度适应性较强.

  20. Optical Absorption Spectra and Electronic Properties of Symmetric and Asymmetric Squaraine Dyes for Use in DSSC Solar Cells: DFT and TD-DFT Studies

    Directory of Open Access Journals (Sweden)

    Reda M. El-Shishtawy

    2016-04-01

    Full Text Available The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1–SQD4 were investigated using density functional theory (DFT and time-dependent (TD-DFT density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time dependent density functionals Perdew, Burke and Ernzerhof (PBE, PBE1PBE (PBE0, and the exchange functional of Tao, Perdew, Staroverov, and Scuseria (TPSSh with 6-311++G** basis set were employed to examine optical absorption properties. In an extensive comparison between the optical data and DFT benchmark calculations, the BEP functional with 6-311++G** basis set was found to be the most appropriate in describing the electronic absorption spectra. The calculated energy values of lowest unoccupied molecular orbitals (LUMO were 3.41, 3.19, 3.38 and 3.23 eV for SQD1, SQD2, SQD3, and SQD4, respectively. These values lie above the LUMO energy (−4.26 eV of the conduction band of TiO2 nanoparticles indicating possible electron injection from the excited dyes to the conduction band of the TiO2 in dye-sensitized solar cells (DSSCs. Also, aromaticity computation for these dyes are in good agreement with the data obtained optically and geometrically with SQD4 as the highest aromatic structure. Based on the optimized molecular geometries, relative positions of the frontier orbitals, and the absorption maxima, we propose that these dyes are suitable components of photovoltaic DSSC devices.

  1. Optical Absorption Spectra and Electronic Properties of Symmetric and Asymmetric Squaraine Dyes for Use in DSSC Solar Cells: DFT and TD-DFT Studies.

    Science.gov (United States)

    El-Shishtawy, Reda M; Elroby, Shaaban A; Asiri, Abdullah M; Müllen, Klaus

    2016-04-01

    The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1-SQD4) were investigated using density functional theory (DFT) and time-dependent (TD-DFT) density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time dependent density functionals Perdew, Burke and Ernzerhof (PBE, PBE1PBE (PBE0)), and the exchange functional of Tao, Perdew, Staroverov, and Scuseria (TPSSh) with 6-311++G** basis set were employed to examine optical absorption properties. In an extensive comparison between the optical data and DFT benchmark calculations, the BEP functional with 6-311++G** basis set was found to be the most appropriate in describing the electronic absorption spectra. The calculated energy values of lowest unoccupied molecular orbitals (LUMO) were 3.41, 3.19, 3.38 and 3.23 eV for SQD1, SQD2, SQD3, and SQD4, respectively. These values lie above the LUMO energy (-4.26 eV) of the conduction band of TiO₂ nanoparticles indicating possible electron injection from the excited dyes to the conduction band of the TiO₂ in dye-sensitized solar cells (DSSCs). Also, aromaticity computation for these dyes are in good agreement with the data obtained optically and geometrically with SQD4 as the highest aromatic structure. Based on the optimized molecular geometries, relative positions of the frontier orbitals, and the absorption maxima, we propose that these dyes are suitable components of photovoltaic DSSC devices.

  2. Matrix-Vector Based Fast Fourier Transformations on SDR Architectures

    Directory of Open Access Journals (Sweden)

    Y. He

    2008-05-01

    Full Text Available Today Discrete Fourier Transforms (DFTs are applied in various radio standards based on OFDM (Orthogonal Frequency Division Multiplex. It is important to gain a fast computational speed for the DFT, which is usually achieved by using specialized Fast Fourier Transform (FFT engines. However, in face of the Software Defined Radio (SDR development, more general (parallel processor architectures are often desirable, which are not tailored to FFT computations. Therefore, alternative approaches are required to reduce the complexity of the DFT. Starting from a matrix-vector based description of the FFT idea, we will present different factorizations of the DFT matrix, which allow a reduction of the complexity that lies between the original DFT and the minimum FFT complexity. The computational complexities of these factorizations and their suitability for implementation on different processor architectures are investigated.

  3. A Swarm Intelligence Based Model for Mobile Cloud Computing

    Directory of Open Access Journals (Sweden)

    Ahmed S. Salama

    2015-01-01

    Full Text Available Mobile Computing (MC provides multi services and a lot of advantages for millions of users across the world over the internet. Millions of business customers have leveraged cloud computing services through mobile devices to get what is called Mobile Cloud Computing (MCC. MCC aims at using cloud computing techniques for storage and processing of data on mobile devices, thereby reducing their limitations. This paper proposes architecture for a Swarm Intelligence Based Mobile Cloud Computing Model (SIBMCCM. A model that uses a proposed Parallel Particle Swarm Optimization (PPSO algorithm to enhance the access time for the mobile cloud computing services which support different E Commerce models and to better secure the communication through the mobile cloud and the mobile commerce transactions.

  4. Sustainable manufacturing for obsolete computers based on 3R engineering

    Institute of Scientific and Technical Information of China (English)

    SHI Pei-jing; XU Yi; WANG Hong-mei; XU Bin-shi

    2005-01-01

    The volume tendency of in-use and end-of-life computers in China were analyzed; the emerging danger of obsolete computers by incorrect treatment was summarized; the integration disposal technologies based on 3R (recycle, remanufacture and reuse) engineering aiming at monitors, electronic devices, metals, plastics materials, and overall computers were put forward; the economic and social benefits were also analyzed. The results show that the integration disposal process of obsolete computer is an optimum approach to save the resource of electromechanical products. Remanufacturing and disposal 100 thousand obsolete computers per year can create profits about RMB10 million yuan and provide employment for 300 persons. It can be deduced that there are great potential opportunities for the obsolete computers disposal industry containing recycle, remanufacture and reuse engineering.

  5. Intricacies of Feedback in Computer-based Prism Adaptation Therapy

    DEFF Research Database (Denmark)

    Wilms, Inge Linda; Rytter, Hana Malá

    whether the PAT method can be executed with similar effect using a computer with a touch screen.   62 healthy subjects were subjected to two experimental conditions: 1) pointing out at targets using the original box, 2) pointing out at targets on a computer attached touch screen. In both conditions...... on the touch screen (indirect feedback), 2) the feedback was provided by seeing one's own pointing finger, with no graphical feedback on the computer screen (direct feedback).   The results show that it is possible to obtain similar aftereffects from PAT by using a computer method but only when providing...... a direct feedback (physical finger) on pointing precision. Attempts to provide feedback indirectly via icons on the computer screen fail to create the aftereffects observed in the original PAT. The findings have direct implications for future implementations of computer-based methods in treatment...

  6. All-optical reservoir computer based on saturation of absorption.

    Science.gov (United States)

    Dejonckheere, Antoine; Duport, François; Smerieri, Anteo; Fang, Li; Oudar, Jean-Louis; Haelterman, Marc; Massar, Serge

    2014-05-05

    Reservoir computing is a new bio-inspired computation paradigm. It exploits a dynamical system driven by a time-dependent input to carry out computation. For efficient information processing, only a few parameters of the reservoir needs to be tuned, which makes it a promising framework for hardware implementation. Recently, electronic, opto-electronic and all-optical experimental reservoir computers were reported. In those implementations, the nonlinear response of the reservoir is provided by active devices such as optoelectronic modulators or optical amplifiers. By contrast, we propose here the first reservoir computer based on a fully passive nonlinearity, namely the saturable absorption of a semiconductor mirror. Our experimental setup constitutes an important step towards the development of ultrafast low-consumption analog computers.

  7. A Computer-based Course in Classical Mechanics.

    Science.gov (United States)

    Kane, D.; Sherwood, B.

    1980-01-01

    Describes and illustrates the tutorial and homework exercise lessons, student routing, course organization, administration, and evaluation of a PLATO computer-based course in classical mechanics. An appendix lists 41 lessons developed for the course. (CMV)

  8. [Computational chemistry in structure-based drug design].

    Science.gov (United States)

    Cao, Ran; Li, Wei; Sun, Han-Zi; Zhou, Yu; Huang, Niu

    2013-07-01

    Today, the understanding of the sequence and structure of biologically relevant targets is growing rapidly and researchers from many disciplines, physics and computational science in particular, are making significant contributions to modern biology and drug discovery. However, it remains challenging to rationally design small molecular ligands with desired biological characteristics based on the structural information of the drug targets, which demands more accurate calculation of ligand binding free-energy. With the rapid advances in computer power and extensive efforts in algorithm development, physics-based computational chemistry approaches have played more important roles in structure-based drug design. Here we reviewed the newly developed computational chemistry methods in structure-based drug design as well as the elegant applications, including binding-site druggability assessment, large scale virtual screening of chemical database, and lead compound optimization. Importantly, here we address the current bottlenecks and propose practical solutions.

  9. Computer-based learning for the enhancement of breastfeeding ...

    African Journals Online (AJOL)

    Computer-based learning for the enhancement of breastfeeding training. ... Methods and materials: The Indian module was adapted to suit the South African ... Results: All reviewers rated their information technology (IT) skills as suffi cient and ...

  10. Problems of Indexing Classes of News Based on the Computed ...

    African Journals Online (AJOL)

    Problems of Indexing Classes of News Based on the Computed Importance of Words. ... Interestingly most readers and patrons of newspapers adopt the rule of the thumb in choosing a suitable newspaper to read/buy. ... Article Metrics.

  11. Milestones Toward Majorana-Based Quantum Computing

    Directory of Open Access Journals (Sweden)

    David Aasen

    2016-08-01

    Full Text Available We introduce a scheme for preparation, manipulation, and read out of Majorana zero modes in semiconducting wires with mesoscopic superconducting islands. Our approach synthesizes recent advances in materials growth with tools commonly used in quantum-dot experiments, including gate control of tunnel barriers and Coulomb effects, charge sensing, and charge pumping. We outline a sequence of milestones interpolating between zero-mode detection and quantum computing that includes (1 detection of fusion rules for non-Abelian anyons using either proximal charge sensors or pumped current, (2 validation of a prototype topological qubit, and (3 demonstration of non-Abelian statistics by braiding in a branched geometry. The first two milestones require only a single wire with two islands, and additionally enable sensitive measurements of the system’s excitation gap, quasiparticle poisoning rates, residual Majorana zero-mode splittings, and topological-qubit coherence times. These pre-braiding experiments can be adapted to other manipulation and read out schemes as well.

  12. A DFT study on the effect of hydrogen in ethylene and propylene polymerization using a Ti-based heterogeneous Ziegler–Natta catalyst

    KAUST Repository

    Bahri-Laleh, Naeimeh

    2012-11-01

    Hydrogenolysis of a series of model Ziegler-Natta (Z-N) catalysts to form Ti-H bond was studied within DFT. We focused our efforts on Ti species attached to the (110) lateral cut of MgCl 2 which exist as different centres including Ti-C 2H 5, Ti-CH 2CH(CH 3) 2, and Ti-CH(CH 3)CH 2CH 3 in ethylene and propylene polymerization. In the next step, reactivity of Ti-H bond towards ethylene and propylene (1,2- and 2,1-) insertion was investigated. Results showed that insertion of ethylene and propylene into Ti-H bond has less barrier, in comparison with their insertion in Ti-C bond, however, ethylene and propylene 2,1- insertion lead to Ti-C 2H 5 and Ti-CH(CH 3) 2 centres respectively, which were stable due to strong β-agostic interactions. Finally, by considering different possible reactions of active centre, activity depression in ethylene polymerization and activity increase in propylene polymerization were explained in detail. © 2012 Elsevier B.V.

  13. Binding modes of phosphonic acid derivatives adsorbed on TiO2 surfaces: Assignments of experimental IR and NMR spectra based on DFT/PBC calculations

    Science.gov (United States)

    Geldof, D.; Tassi, M.; Carleer, R.; Adriaensens, P.; Roevens, A.; Meynen, V.; Blockhuys, F.

    2017-01-01

    A DFT study on the adsorption of a series of phosphonic acids (PAs) on the TiO2 anatase (101) and (001) surfaces was performed. The adsorption energies and geometries of the most stable binding modes were compared to literature data and the effect of the inclusion of dispersion forces in the energy calculations was gauged. As the (101) surface is the most exposed surface of TiO2 anatase, the calculated chemical shifts and vibrational frequencies of PAs adsorbed on this surface were compared to experimental 31P and 17O NMR and IR data in order to assign the two possible binding modes (mono- and bidentate) to peaks and bands in these spectra; due to the corrugated nature of anatase (101) tridentate binding is not possible on this surface. Analysis of the calculated and experimental 31P chemical shifts indicates that both monodentate and bidentate binding modes are present. For the reactive (001) surface, the results of the calculations indicate that both bi- and tridentate binding modes result in stable systems. Due to the particular sensitivity of 17O chemical shifts to hydrogen bonding and solvent effects, the model used is insufficient to assign these spectra at present. Comparison of calculated and experimental IR spectra leads to the conclusion that IR spectroscopy is not suitable for the characterization of the different binding modes of the adsorption complexes.

  14. Big data mining analysis method based on cloud computing

    Science.gov (United States)

    Cai, Qing Qiu; Cui, Hong Gang; Tang, Hao

    2017-08-01

    Information explosion era, large data super-large, discrete and non-(semi) structured features have gone far beyond the traditional data management can carry the scope of the way. With the arrival of the cloud computing era, cloud computing provides a new technical way to analyze the massive data mining, which can effectively solve the problem that the traditional data mining method cannot adapt to massive data mining. This paper introduces the meaning and characteristics of cloud computing, analyzes the advantages of using cloud computing technology to realize data mining, designs the mining algorithm of association rules based on MapReduce parallel processing architecture, and carries out the experimental verification. The algorithm of parallel association rule mining based on cloud computing platform can greatly improve the execution speed of data mining.

  15. An overview of computer-based natural language processing

    Science.gov (United States)

    Gevarter, W. B.

    1983-01-01

    Computer based Natural Language Processing (NLP) is the key to enabling humans and their computer based creations to interact with machines in natural language (like English, Japanese, German, etc., in contrast to formal computer languages). The doors that such an achievement can open have made this a major research area in Artificial Intelligence and Computational Linguistics. Commercial natural language interfaces to computers have recently entered the market and future looks bright for other applications as well. This report reviews the basic approaches to such systems, the techniques utilized, applications, the state of the art of the technology, issues and research requirements, the major participants and finally, future trends and expectations. It is anticipated that this report will prove useful to engineering and research managers, potential users, and others who will be affected by this field as it unfolds.

  16. COMPUTING

    CERN Multimedia

    M. Kasemann

    Overview During the past three months activities were focused on data operations, testing and re-enforcing shift and operational procedures for data production and transfer, MC production and on user support. Planning of the computing resources in view of the new LHC calendar in ongoing. Two new task forces were created for supporting the integration work: Site Commissioning, which develops tools helping distributed sites to monitor job and data workflows, and Analysis Support, collecting the user experience and feedback during analysis activities and developing tools to increase efficiency. The development plan for DMWM for 2009/2011 was developed at the beginning of the year, based on the requirements from the Physics, Computing and Offline groups (see Offline section). The Computing management meeting at FermiLab on February 19th and 20th was an excellent opportunity discussing the impact and for addressing issues and solutions to the main challenges facing CMS computing. The lack of manpower is particul...

  17. A novel bit-quad-based Euler number computing algorithm.

    Science.gov (United States)

    Yao, Bin; He, Lifeng; Kang, Shiying; Chao, Yuyan; Zhao, Xiao

    2015-01-01

    The Euler number of a binary image is an important topological property in computer vision and pattern recognition. This paper proposes a novel bit-quad-based Euler number computing algorithm. Based on graph theory and analysis on bit-quad patterns, our algorithm only needs to count two bit-quad patterns. Moreover, by use of the information obtained during processing the previous bit-quad, the average number of pixels to be checked for processing a bit-quad is only 1.75. Experimental results demonstrated that our method outperforms significantly conventional Euler number computing algorithms.

  18. Enhancement of DFT-calculations at petascale: Nuclear Magnetic Resonance, Hybrid Density Functional Theory and Car-Parrinello calculations

    Science.gov (United States)

    Varini, Nicola; Ceresoli, Davide; Martin-Samos, Layla; Girotto, Ivan; Cavazzoni, Carlo

    2013-08-01

    One of the most promising techniques used for studying the electronic properties of materials is based on Density Functional Theory (DFT) approach and its extensions. DFT has been widely applied in traditional solid state physics problems where periodicity and symmetry play a crucial role in reducing the computational workload. With growing compute power capability and the development of improved DFT methods, the range of potential applications is now including other scientific areas such as Chemistry and Biology. However, cross disciplinary combinations of traditional Solid-State Physics, Chemistry and Biology drastically improve the system complexity while reducing the degree of periodicity and symmetry. Large simulation cells containing of hundreds or even thousands of atoms are needed to model these kind of physical systems. The treatment of those systems still remains a computational challenge even with modern supercomputers. In this paper we describe our work to improve the scalability of Quantum ESPRESSO (Giannozzi et al., 2009 [3]) for treating very large cells and huge numbers of electrons. To this end we have introduced an extra level of parallelism, over electronic bands, in three kernels for solving computationally expensive problems: the Sternheimer equation solver (Nuclear Magnetic Resonance, package QE-GIPAW), the Fock operator builder (electronic ground-state, package PWscf) and most of the Car-Parrinello routines (Car-Parrinello dynamics, package CP). Final benchmarks show our success in computing the Nuclear Magnetic Response (NMR) chemical shift of a large biological assembly, the electronic structure of defected amorphous silica with hybrid exchange-correlation functionals and the equilibrium atomic structure of height Porphyrins anchored to a Carbon Nanotube, on many thousands of CPU cores.

  19. Domain Decomposition Based High Performance Parallel Computing

    CERN Document Server

    Raju, Mandhapati P

    2009-01-01

    The study deals with the parallelization of finite element based Navier-Stokes codes using domain decomposition and state-ofart sparse direct solvers. There has been significant improvement in the performance of sparse direct solvers. Parallel sparse direct solvers are not found to exhibit good scalability. Hence, the parallelization of sparse direct solvers is done using domain decomposition techniques. A highly efficient sparse direct solver PARDISO is used in this study. The scalability of both Newton and modified Newton algorithms are tested.

  20. Benchmarking the DFT+U method for thermochemical calculations of uranium molecular compounds and solids.

    Science.gov (United States)

    Beridze, George; Kowalski, Piotr M

    2014-12-18

    Ability to perform a feasible and reliable computation of thermochemical properties of chemically complex actinide-bearing materials would be of great importance for nuclear engineering. Unfortunately, density functional theory (DFT), which on many instances is the only affordable ab initio method, often fails for actinides. Among various shortcomings, it leads to the wrong estimate of enthalpies of reactions between actinide-bearing compounds, putting the applicability of the DFT approach to the modeling of thermochemical properties of actinide-bearing materials into question. Here we test the performance of DFT+U method--a computationally affordable extension of DFT that explicitly accounts for the correlations between f-electrons - for prediction of the thermochemical properties of simple uranium-bearing molecular compounds and solids. We demonstrate that the DFT+U approach significantly improves the description of reaction enthalpies for the uranium-bearing gas-phase molecular compounds and solids and the deviations from the experimental values are comparable to those obtained with much more computationally demanding methods. Good results are obtained with the Hubbard U parameter values derived using the linear response method of Cococcioni and de Gironcoli. We found that the value of Coulomb on-site repulsion, represented by the Hubbard U parameter, strongly depends on the oxidation state of uranium atom. Last, but not least, we demonstrate that the thermochemistry data can be successfully used to estimate the value of the Hubbard U parameter needed for DFT+U calculations.

  1. Safeguards instrumentation: a computer-based catalog

    Energy Technology Data Exchange (ETDEWEB)

    Fishbone, L.G.; Keisch, B.

    1981-08-01

    The information contained in this catalog is needed to provide a data base for safeguards studies and to help establish criteria and procedures for international safeguards for nuclear materials and facilities. The catalog primarily presents information on new safeguards equipment. It also describes entire safeguards systems for certain facilities, but it does not describe the inspection procedures. Because IAEA safeguards do not include physical security, devices for physical protection (as opposed to containment and surveillance) are not included. An attempt has been made to list capital costs, annual maintenance costs, replacement costs, and useful lifetime for the equipment. For equipment which is commercially available, representative sources have been listed whenever available.

  2. Axially chiral benzimidazolium based silver(I) and gold(I) bis-NHC complexes of R-BINOL scaffold: synthesis, characterization and DFT studies

    Indian Academy of Sciences (India)

    SONALI RAMGOPAL MAHULE

    2017-09-01

    The axially chiral ligand of R-BINOL scaffold was synthesized by a series of manipulations which involved different chemical reactions to obtain the desired sliver(I) and gold(I) {[L(L' -NHC) ₂]M}Cl (L = 3,3' -dimethyl-2,2' -dimethoxy-1,1' -binaphthyl, L' = i-propyl-benzo[d]imidazole) (M =Ag and Au)complexes. Enantiopure R-BINOL was employed as a basic unit to synthesize a benzimidazole based bis- NHC ligand 1g which was obtained through the formation of different intermediate 1(a-f) compounds. The newly synthesized bis-NHC ligand precursor (1g) and its corresponding {[L(L' -NHC) ₂]Ag}Cl (1h) and {[L(L' _-NHC) ₂]Au}Cl (1i) complexes were characterized by different spectroscopic techniques. The geometries of the optimized structure of the complexes 1h and 1i were computed at the B3LYP/SDD, 6-31G(d) level. Lowtemperature fluorescence spectroscopic studies did not show any evidence for the weak metal-metal interaction in these complexes.

  3. Thiazole-based nitrogen mustards: Design, synthesis, spectroscopic studies, DFT calculation, molecular docking, and antiproliferative activity against selected human cancer cell lines

    Science.gov (United States)

    Łączkowski, Krzysztof Z.; Świtalska, Marta; Baranowska-Łączkowska, Angelika; Plech, Tomasz; Paneth, Agata; Misiura, Konrad; Wietrzyk, Joanna; Czaplińska, Barbara; Mrozek-Wilczkiewicz, Anna; Malarz, Katarzyna; Musioł, Robert; Grela, Izabela

    2016-09-01

    Synthesis, characterization and investigation of antiproliferative activity of ten thiazole-based nitrogen mustard against human cancer cells lines (MV4-11, A549, MCF-7 and HCT116) and normal mouse fibroblast (BALB/3T3) is presented. The structures of novel compounds were determined using 1H and 13C NMR, FAB(+)-MS, and elemental analyses. Among the derivatives, 5b, 5c, 5e, 5f and 5i were found to exhibit high activity against human leukaemia MV4-11 cells with IC50 values of 2.17-4.26 μg/ml. The cytotoxic activity of compound 5c and 5f against BALB/3T3 cells is up to 20 times lower than against cancer cell lines. Our results also show that compounds 5e and 5i have very strong activity against MCF-7 and HCT116 with IC50 values of 3.02-4.13 μg/ml. Moreover, spectroscopic characterization and cellular localization for selected compound were performed. In order to identify potential drug targets we perform computer simulations with DNA-binding site of hTopoI and hTopoII and quantum chemical calculation of interaction and binding energies in complexes of the five most active compounds with guanine.

  4. Gas phase reaction of phosphorus trichloride and methanol: Matrix isolation infrared and DFT studies

    Science.gov (United States)

    Joshi, Prasad Ramesh; Ramanathan, N.; Sundararajan, K.; Sankaran, K.

    2015-11-01

    Gas phase reaction of phosphorus trichloride (PCl3) and methanol (CH3OH) was carried out with different ratios of PCl3:CH3OH:N2 (1:1:1000, 1:2:1000 and 1:3:1000) and the products were identified using matrix isolation infrared spectroscopy. For the 1:1 and 1:2 ratios of PCl3:CH3OH, dichloro methyl phosphite (DCMP) and methyl chloride (CH3Cl) were the products formed. Interestingly, only methyl chloride (CH3Cl) was observed for the 1:3 ratio of PCl3:CH3OH. DFT computations were carried out at B3LYP/6-311++G(d,p) level of theory to give insights into the formation of the reaction products. Based on the experimental findings and computations a reaction mechanism has been proposed through a nucleophilic substitution reaction to explain the formation of the products.

  5. Towards a fullerene-based quantum computer

    Energy Technology Data Exchange (ETDEWEB)

    Benjamin, Simon C [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Ardavan, Arzhang [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Briggs, G Andrew D [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Britz, David A [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Gunlycke, Daniel [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Jefferson, John [QinetiQ, St Andrews Road, Malvern, WR14 3PS (United Kingdom); Jones, Mark A G [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Leigh, David F [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Lovett, Brendon W [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Khlobystov, Andrei N [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Lyon, S A [Department of Electrical Engineering, Princeton University, Princeton, NJ 08544 (United States); Morton, John J L [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Porfyrakis, Kyriakos [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Sambrook, Mark R [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Tyryshkin, Alexei M [Department of Electrical Engineering, Princeton University, Princeton, NJ 08544 (United States)

    2006-05-31

    Molecular structures appear to be natural candidates for a quantum technology: individual atoms can support quantum superpositions for long periods, and such atoms can in principle be embedded in a permanent molecular scaffolding to form an array. This would be true nanotechnology, with dimensions of order of a nanometre. However, the challenges of realizing such a vision are immense. One must identify a suitable elementary unit and demonstrate its merits for qubit storage and manipulation, including input/output. These units must then be formed into large arrays corresponding to an functional quantum architecture, including a mechanism for gate operations. Here we report our efforts, both experimental and theoretical, to create such a technology based on endohedral fullerenes or 'buckyballs'. We describe our successes with respect to these criteria, along with the obstacles we are currently facing and the questions that remain to be addressed.

  6. Risk-Based Computational Prototyping (Briefing Charts)

    Science.gov (United States)

    2010-10-01

    2010) Prof Huang, Director  Dr. Beran, PM • Prof Missoum, Mr. Basudhar (UA, Tucson) and Dr. Lambe (MSSRC) – RBDO  with LCO  • Prof Dong and Mr. Gaston...periodic formulation 21 Approved for public release. Reliability‐Based Design Optimization ( RBDO ) Goal: Examine use of...amp   x = response variables d = design variables    aluminum g(x(d, E, M∞ )) > 0; side constraints on d RBDO M∞ Generally, the designed

  7. Towards a fullerene-based quantum computer

    CERN Document Server

    Benjamin, S C; Briggs, G A D; Britz, D A; Gunlycke, D; Jefferson, J; Jones, M A G; Khlobystov, A N; Leigh, D F; Lovett, B W; Lyon, S A; Morton, J J L; Porfyrakis, K; Sambrook, M R; Tyryshkin, A M; Ardavan, Arzhang; Benjamin, Simon C; Britz, David A; Gunlycke, Daniel; Jefferson, John; Jones, Mark A G; Khlobystov, Andrei N; Leigh, David F; Lovett, Brendon W; Morton, John J L; Porfyrakis, Kyriakos; Sambrook, Mark R; Tyryshkin, Alexei M

    2005-01-01

    Molecular structures appear to be natural candidates for a quantum technology: individual atoms can support quantum superpositions for long periods, and such atoms can in principle be embedded in a permanent molecular scaffolding to form an array. This would be true nanotechnology, with dimensions of order of a nanometre. However, the challenges of realising such a vision are immense. One must identify a suitable elementary unit and demonstrate its merits for qubit storage and manipulation, including input / output. These units must then be formed into large arrays corresponding to an functional quantum architecture, including a mechanism for gate operations. Here we report our efforts, both experimental and theoretical, to create such a technology based on endohedral fullerenes or 'buckyballs'. We describe our successes with respect to these criteria, along with the obstacles we are currently facing and the questions that remain to be addressed.

  8. Higher coordinate gold(I) complexes with the weak Lewis base tri(4-fluorophenyl) phosphine. Synthesis, structural, luminescence, and DFT studies

    Science.gov (United States)

    Agbeworvi, George; Assefa, Zerihun; Sykora, Richard E.; Taylor, Jared; Crawford, Carlos

    2016-03-01

    The structures and spectroscopic properties of two high coordinate gold(I) phosphine complexes with the TFFPP=tri(4-fluorophenyl)phosphine ligand are reported. Synthesis in a 1:3 metal to ligand ratio provided the compound [AuCl(TFFPP)3] (2) that crystallize in the P 1 bar space group, where the asymmetric unit consists of three independent molecules. In all three sites, two sets of bond angles display distinctly different ranges. The three P-Au-P angles have average values of 117.92°, 117.57°, and 114.78° for sites A, B, and C, with the corresponding P-Au-Cl angles of 98.31°, 99.05°, and 103.38°, respectively. The chloride ion coordinates as the fourth ligand, at the corresponding Au-Cl distance of 2.7337, 2.6825, and 2.6951 Å for the three sites. This distance is longer by 0.40-0.45 Å than the Au-Cl distance found in the mono TFFPP complex 1 (2.285 Å) indicating a weakening of the Au-Cl interaction as the coordination number increases. In compound 3, [Au(TFFPP)3]Cl·½CH2Cl2·H2O, the structure consists of three phosphine ligands bound to the gold(I) atom, but the Cl- exists as uncoordinated counter anion. The structural differences observed in the two complexes are attributable to crystal-packing effects caused by the introduction of H-bonding as well as enhanced intra and inter-molecular π-interaction in 3. The photoluminescence of the complexes compared with that of the ligand show ligand centered emission perturbed by the metal coordination. Theoretical DFT studies conducted on these complexes supports assignments of the electronic transitions observed in these systems.

  9. Synthesis, characterization, DFT calculations and biological studies of Mn(II), Fe(II), Co(II) and Cd(II) complexes based on a tetradentate ONNO donor Schiff base ligand

    Science.gov (United States)

    Abdel-Rahman, Laila H.; Ismail, Nabawia M.; Ismael, Mohamed; Abu-Dief, Ahmed M.; Ahmed, Ebtehal Abdel-Hameed

    2017-04-01

    This study highlights synthesis and characterization of a tetradentate ONNO Schiff base ligand namely (1, 1‧- (pyridine-2, 3-dimethyliminomethyl) naphthalene-2, 2‧-diol) and hereafter denotes as "HNDAP″ and selected metal complexes including Mn(II), Fe(II), Co(II) and Cd(II) as a central metal. HNDAP was synthesized from 1:2 M ratio condensation of 2, 3-diaminopyridine and 2- hydroxy-1-naphthaldhyde, respectively. The stoichiometric ratios of the prepared complexes were estimated using complementary techniques such as; elemental analyses (-C, H, N), FT-IR, magnetic measurements and molar conductivity. Furthermore, their physicochemical studies were carried out using thermal TGA, DTA and kinetic-thermodynamic studies along with DFT calculations. The results of elemental analyses showed that these complexes are present in a 1:1 metal-to- ligand molar ratio. Moreover, the magnetic susceptibilities values at room temperature revealed that Mn(II), Fe(II) and Co(II) complexes are paramagnetic in nature and have an octahedral (Oh) geometry. In contrast, Cd(II) is diamagnetic and stabilizes in square planar sites. The molar conductivity measurements indicated that all complexes are nonelectrolytes in dimethyl formamide. Spectral data suggested that the ligand is as tetradentate and coordinated with Co(II) ion through two phenolic OH and two azomethine nitrogen. However, for Mn(II), Fe(II) and Cd(II) complexes, the coordination occurred through two phenolic oxygen and two azomethine nitrogen with deprotonation of OH groups. The proposed chemical structures have been validated by quantum mechanics calculations. Antimicrobial activities of both the HNDAP Schiff base ligand and its metal complexes were tested against strains of Gram (-ve) E. coli and Gram (+ve) B. subtilis and S. aureus bacteria and C. albicans, A. flavus and T. rubrum fungi. All the prepared compounds showed good results of inhibition against the selected pathogenic microorganisms. The investigated

  10. TD-DFT Insight into Photodissociation of Co-C Bond in Coenzyme B12

    Science.gov (United States)

    Kozlowski, Pawel; Liu, Hui; Kornobis, Karina; Lodowski, Piotr; Jaworska, Maria

    2013-12-01

    Coenzyme B12 (AdoCbl) is one of the most biologically active forms of vitamin B12, and continues to be a topic of active research interest. The mechanism of Co-C bond cleavage in AdoCbl, and the corresponding enzymatic reactions are however, not well understood at the molecular level. In this work, time-dependent density functional theory (TD-DFT) has been applied to investigate the photodissociation of coenzyme B12. To reduce computational cost, while retaining the major spectroscopic features of AdoCbl, a truncated model based on ribosylcobalamin (RibCbl) was used to simulate Co-C photodissociation. Equilibrium geometries of RibCbl were obtained by optimization at the DFT/BP86/TZVP level of theory, and low-lying excited states were calculated by TD-DFT using the same functional and basis set. The calculated singlet states, and absorption spectra were simulated in both the gas phase, and water, using the polarizable continuum model (PCM). Both spectra were in reasonable agreement with experimental data, and potential energy curves based on vertical excitations were plotted to explore the nature of Co-C bond dissociation. It was found that a repulsive 3(σCo-C → σ*Co-C) triplet state became dissociative at large Co-C bond distance, similar to a previous observation for methylcobalamin (MeCbl). Furthermore, potential energy surfaces (PESs) obtained as a function of both Co-CRib and Co-NIm distances, identify the S1 state as a key intermediate generated during photoexcitation of RibCbl, attributed to a mixture of a MLCT (metal-to-ligand charge transfer) and a σ bonding-ligand charge transfer (SBLCT) states.

  11. Development and implementation of a DFT/MIA method

    Science.gov (United States)

    Rousseau, Bart

    2001-11-01

    In the last half of the century that has passed since the advent of the quantum chemical era the computational quantum chemistry methods have matured into valuable tools for researchers in industry and academia alike. However, for these methods to be competitive with e.g. the high-throughput experimental techniques used in the pharmaceutical industry, they must not only be accurate but at the same time must be computationally inexpensive. Most of the contemporary computational methods succeed only in fulfilling one of these criteria. Therefore the goal of this Ph.D. project was to combine the MIA approach, which allows efficient SCF calculations on large systems, and the DFT method, that takes electron correlation into account at a moderate computational cost. The new DFT method thus obtained, the DFT/MIA method, allows for efficient correlated calculations on large systems. The MIA method, an efficient combination of the Multiplicative Integral Approximation and the direct SCF procedure, is implemented in the ab-initio quantum chemical program package BRABO. In the MIA approximation the product of two basis functions is expanded in terms of an auxiliary basis set. This reduces the N4 four-center two-electron integrals to a sum of N3 three-center two-electron integrals. In addition this allows for a very fast build- up of the Fock matrix. The MIA approach has already proven its effectiveness in calculations on systems that belong to the largest that have been calculated at this level of theory, such as the calculation on the 46- peptide crambin. In addition this method was implemented using the `Parallel Virtual Machine' method, allowing parallel execution on a heterogeneous cluster of workstations. The MIA approach is applied to both the calculation of the electron density and the calculation of the exchange-correlation contribution to the Fock matrix. For both these quantities a recursive procedure is used. Test calculations on water clusters ranging in size from

  12. Thiol-thione tautomeric analysis, spectroscopic (FT-IR, Laser-Raman, NMR and UV-vis) properties and DFT computations of 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule.

    Science.gov (United States)

    Gökce, Halil; Öztürk, Nuri; Ceylan, Ümit; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

    2016-06-15

    In this study, the 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule (C7H6N4S) molecule has been characterized by using FT-IR, Laser-Raman, NMR and UV-vis spectroscopies. Quantum chemical calculations have been performed to investigate the molecular structure (thione-thiol tautomerism), vibrational wavenumbers, electronic transition absorption wavelengths in DMSO solvent and vacuum, proton and carbon-13 NMR chemical shifts and HOMOs-LUMOs energies at DFT/B3LYP/6-311++G(d,p) level for all five tautomers of the title molecule. The obtained results show that the calculated vibrational wavenumbers, NMR chemical shifts and UV-vis wavelengths are in a good agreement with experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Thiol-thione tautomeric analysis, spectroscopic (FT-IR, Laser-Raman, NMR and UV-vis) properties and DFT computations of 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule

    Science.gov (United States)

    Gökce, Halil; Öztürk, Nuri; Ceylan, Ümit; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

    2016-06-01

    In this study, the 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule (C7H6N4S) molecule has been characterized by using FT-IR, Laser-Raman, NMR and UV-vis spectroscopies. Quantum chemical calculations have been performed to investigate the molecular structure (thione-thiol tautomerism), vibrational wavenumbers, electronic transition absorption wavelengths in DMSO solvent and vacuum, proton and carbon-13 NMR chemical shifts and HOMOs-LUMOs energies at DFT/B3LYP/6-311 ++G(d,p) level for all five tautomers of the title molecule. The obtained results show that the calculated vibrational wavenumbers, NMR chemical shifts and UV-vis wavelengths are in a good agreement with experimental data.

  14. ZrOCl2.8H2O on montmorillonite K10: an efficient green catalyst for One-pot synthesis of highly substituted imidazoles under Solvent-Free Conditions: DFT Computational investigation

    Directory of Open Access Journals (Sweden)

    Ahmad Movahedpour

    2017-01-01

    Full Text Available ZrOCl2.8H2O/K10 has been found to be an extremely efficient catalyst for the preparation of synthesis of 2,4,5- trisubstituted and 1,2,4,5-tetra substituted imidazoles in excellent yields. This catalystexhibited remarkable catalytic activity with respect to the reaction time (2-3min, amount of catalyst. Present protocol using ZrOCl2.8H2O/K10 as catalyst is convincingly superior to the recently reported methodologies. Density functional theory (DFT method and B3LYP/6-31G(d,p level of theory were used to determine some parameters such as vibrational modes, dipole moment (μ, EHOMO, ELUMO and gap energy (∆E of compounds.

  15. DFT computations support the σ-complex assisted metathesis (σ-CAM) mechanism for the 1,4-Rh shift of Cp*Rh(III)-(η(1)-β-styryl) complexes.

    Science.gov (United States)

    Li, Yougui; He, Gang; Kantchev, Eric Assen B

    2014-11-28

    DFT calculations support the σ-complex assisted metathesis (σ-CAM) mechanism recently proposed for the first 1,4-Rh shift of a Rh(III) complex rather than the oxidative addition/reductive elimination pathway characteristic of Rh(i). A single, concerted TS (ΔG(‡) = 27-34 kcal mol(-1)) was found and its electronic structure characterized by Bader's AIM analysis. The 4-centered TS is characterized by a enhanced charge separation (Rh and H atoms - positive, both C atoms - negative) relative to the σ-vinyl Rh starting material and the σ-aryl-Rh product. The AIM topological analysis of the electron density reveals a network of interactions: Rh with H as well as both Rh and H with both C(vinyl) and C(aryl) in the TS and confirms the C(vinyl)-Rh agnostic interaction observed experimentally in the σ-aryl-Rh product.

  16. A community-based study of asthenopia in computer operators

    Directory of Open Access Journals (Sweden)

    Bhanderi Dinesh

    2008-01-01

    Full Text Available Context: There is growing body of evidence that use of computers can adversely affect the visual health. Considering the rising number of computer users in India, computer-related asthenopia might take an epidemic form. In view of that, this study was undertaken to find out the magnitude of asthenopia in computer operators and its relationship with various personal and workplace factors. Aims: To study the prevalence of asthenopia among computer operators and its association with various epidemiological factors. Settings and Design: Community-based cross-sectional study of 419 subjects who work on computer for varying period of time. Materials and Methods: Four hundred forty computer operators working in different institutes were selected randomly. Twenty-one did not participate in the study, making the nonresponse rate 4.8%. Rest of the subjects (n = 419 were asked to fill a pre-tested questionnaire, after obtaining their verbal consent. Other relevant information was obtained by personal interview and inspection of workstation. Statistical Analysis Used: Simple proportions and Chi-square test. Results: Among the 419 subjects studied, 194 (46.3% suffered from asthenopia during or after work on computer. Marginally higher proportion of asthenopia was noted in females compared to males. Occurrence of asthenopia was significantly associated with age of starting use of computer, presence of refractive error, viewing distance, level of top of the computer screen with respect to eyes, use of antiglare screen and adjustment of contrast and brightness of monitor screen. Conclusions: Prevalence of asthenopia was noted to be quite high among computer operators, particularly in those who started its use at an early age. Individual as well as work-related factors were found to be predictive of asthenopia.

  17. Redesigning Computer-based Learning Environments: Evaluation as Communication

    CERN Document Server

    Brust, Matthias R; Ricarte, Ivan M L

    2007-01-01

    In the field of evaluation research, computer scientists live constantly upon dilemmas and conflicting theories. As evaluation is differently perceived and modeled among educational areas, it is not difficult to become trapped in dilemmas, which reflects an epistemological weakness. Additionally, designing and developing a computer-based learning scenario is not an easy task. Advancing further, with end-users probing the system in realistic settings, is even harder. Computer science research in evaluation faces an immense challenge, having to cope with contributions from several conflicting and controversial research fields. We believe that deep changes must be made in our field if we are to advance beyond the CBT (computer-based training) learning model and to build an adequate epistemology for this challenge. The first task is to relocate our field by building upon recent results from philosophy, psychology, social sciences, and engineering. In this article we locate evaluation in respect to communication s...

  18. Micromechanics-Based Computational Simulation of Ceramic Matrix Composites

    Science.gov (United States)

    Murthy, Pappu L. N.; Mutal, Subodh K.; Duff, Dennis L. (Technical Monitor)

    2003-01-01

    Advanced high-temperature Ceramic Matrix Composites (CMC) hold an enormous potential for use in aerospace propulsion system components and certain land-based applications. However, being relatively new materials, a reliable design properties database of sufficient fidelity does not yet exist. To characterize these materials solely by testing is cost and time prohibitive. Computational simulation then becomes very useful to limit the experimental effort and reduce the design cycle time, Authors have been involved for over a decade in developing micromechanics- based computational simulation techniques (computer codes) to simulate all aspects of CMC behavior including quantification of scatter that these materials exhibit. A brief summary/capability of these computer codes with typical examples along with their use in design/analysis of certain structural components is the subject matter of this presentation.

  19. Grid Computing based on Game Optimization Theory for Networks Scheduling

    Directory of Open Access Journals (Sweden)

    Peng-fei Zhang

    2014-05-01

    Full Text Available The resource sharing mechanism is introduced into grid computing algorithm so as to solve complex computational tasks in heterogeneous network-computing problem. However, in the Grid environment, it is required for the available resource from network to reasonably schedule and coordinate, which can get a good workflow and an appropriate network performance and network response time. In order to improve the performance of resource allocation and task scheduling in grid computing method, a game model based on non-cooperation game is proposed. Setting the time and cost of user’s resource allocation can increase the performance of networks, and incentive resource of networks uses an optimization scheduling algorithm, which minimizes the time and cost of resource scheduling. Simulation experiment results show the feasibility and suitability of model. In addition, we can see from the experiment result that model-based genetic algorithm is the best resource scheduling algorithm

  20. An Introduction to the Computer-based TOEFL

    Institute of Scientific and Technical Information of China (English)

    CHEN Jing

    2001-01-01

    TOEFL,which aims to measure the English proficiency of test-takers whose first language is not English, is a familiar test to students around the world. The number of people who take the TEOFL is growing rapidly as the influence of the TOEFL is expanding. In 2002-2003, the computer-based TOEFL test will be introduced into China to replace the old paper-based test. So it is quite necessary for people who are preparing to take the computer-based TOEFL test to learn something about it.

  1. Identifying barriers for implementation of computer based nursing documentation.

    Science.gov (United States)

    Vollmer, Anna-Maria; Prokosch, Hans-Ulrich; Bürkle, Thomas

    2014-01-01

    This study was undertaken in the planning phase for the introduction of a comprehensive computer based nursing documentation system at Erlangen University Hospital. There, we expect a wide range of difficult organizational changes, because the nurses currently neither used computer based nursing documentation nor did they follow strongly the nursing process model within paper based documentation. Thus we were eager to recognize potential pitfalls early and to identify potential barriers for digital nursing documentation. In a questionnaire study we surveyed all German university hospitals for their experience with the implementation of computer based nursing documentation implementation. We received answers from 11 of the 23 hospitals. Furthermore we performed a questionnaire study about expectations and fears among the nurses of four pilot wards of our hospital. Most respondents stated a positive attitude towards the nursing process documentation, but many respondents note technical (e.g. bad performance of the software) and organizational barriers (e.g. lack of time).

  2. Randomized benchmarking in measurement-based quantum computing

    Science.gov (United States)

    Alexander, Rafael N.; Turner, Peter S.; Bartlett, Stephen D.

    2016-09-01

    Randomized benchmarking is routinely used as an efficient method for characterizing the performance of sets of elementary logic gates in small quantum devices. In the measurement-based model of quantum computation, logic gates are implemented via single-site measurements on a fixed universal resource state. Here we adapt the randomized benchmarking protocol for a single qubit to a linear cluster state computation, which provides partial, yet efficient characterization of the noise associated with the target gate set. Applying randomized benchmarking to measurement-based quantum computation exhibits an interesting interplay between the inherent randomness associated with logic gates in the measurement-based model and the random gate sequences used in benchmarking. We consider two different approaches: the first makes use of the standard single-qubit Clifford group, while the second uses recently introduced (non-Clifford) measurement-based 2-designs, which harness inherent randomness to implement gate sequences.

  3. Sensitive Data Protection Based on Intrusion Tolerance in Cloud Computing

    Directory of Open Access Journals (Sweden)

    Jingyu Wang

    2011-02-01

    Full Text Available Service integration and supply on-demand coming from cloud computing can significantly improve the utilization of computing resources and reduce power consumption of per service, and effectively avoid the error of computing resources. However, cloud computing is still facing the problem of intrusion tolerance of the cloud computing platform and sensitive data of new enterprise data center. In order to address the problem of intrusion tolerance of cloud computing platform and sensitive data in new enterprise data center, this paper constructs a virtualization intrusion tolerance system based on cloud computing by researching on the existing virtualization technology, and then presents a method of intrusion tolerance to protect sensitive data in cloud data center based on virtual adversary structure by utilizing secret sharing. This system adopts the method of hybrid fault model, active and passive replicas, state update and transfer, proactive recovery and diversity, and initially implements to tolerate F faulty replicas in N=2F+1 replicas and ensure that only F+1 active replicas to execute during the intrusion-free stage. The remaining replicas are all put into passive mode, which significantly reduces the resource consuming in cloud platform. At last we prove the reconstruction and confidentiality property of sensitive data by utilizing secret sharing.

  4. Radiation Tolerant, FPGA-Based SmallSat Computer System

    Science.gov (United States)

    LaMeres, Brock J.; Crum, Gary A.; Martinez, Andres; Petro, Andrew

    2015-01-01

    The Radiation Tolerant, FPGA-based SmallSat Computer System (RadSat) computing platform exploits a commercial off-the-shelf (COTS) Field Programmable Gate Array (FPGA) with real-time partial reconfiguration to provide increased performance, power efficiency and radiation tolerance at a fraction of the cost of existing radiation hardened computing solutions. This technology is ideal for small spacecraft that require state-of-the-art on-board processing in harsh radiation environments but where using radiation hardened processors is cost prohibitive.

  5. Agent-based computational economics using NetLogo

    CERN Document Server

    Damaceanu, Romulus-Catalin

    2013-01-01

    Agent-based Computational Economics using NetLogo explores how researchers can create, use and implement multi-agent computational models in Economics by using NetLogo software platform. Problems of economic science can be solved using multi-agent modelling (MAM). This technique uses a computer model to simulate the actions and interactions of autonomous entities in a network, in order to analyze the effects on the entire economic system. MAM combines elements of game theory, complex systems, emergence and evolutionary programming. The Monte Carlo method is also used in this e-book to introduc

  6. A Logistics Distribution Plan Based on Cloud Computing

    Directory of Open Access Journals (Sweden)

    Zhou Feng

    2013-12-01

    Full Text Available Aiming at the problems of lowing informatization level and degree of specialization, high consumption and low efficiency in logistics and distribution industry, this paper analyzes the characteristics of cloud computing and the actual needs of enterprise logistics. On this basis, depth study of the logistics and distribution needs of the cloud computing architecture, depth study of the cloud computing architecture in the logistics and distribution needs, and then propose a cloud-based modern logistics solutions, for the development of modern logistics provides a new operating mode

  7. Protecting Terminals by Security Domain Mechanism Based on Trusted Computing

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zheng; ZHANG Jun; LI Jian; LIU Yi

    2006-01-01

    Networks are composed with servers and rather larger amounts of terminals and most menace of attack and virus come from terminals. Eliminating malicious code and access or breaking the conditions only under witch attack or virus can be invoked in those terminals would be the most effective way to protect information systems. The concept of trusted computing was first introduced into terminal virus immunity. Then a model of security domain mechanism based on trusted computing to protect computers from proposed from abstracting the general information systems. The principle of attack resistant and venture limitation of the model was demonstrated by means of mathematical analysis, and the realization of the model was proposed.

  8. Nanophotonic quantum computer based on atomic quantum transistor

    Energy Technology Data Exchange (ETDEWEB)

    Andrianov, S N [Institute of Advanced Research, Academy of Sciences of the Republic of Tatarstan, Kazan (Russian Federation); Moiseev, S A [Kazan E. K. Zavoisky Physical-Technical Institute, Kazan Scientific Center, Russian Academy of Sciences, Kazan (Russian Federation)

    2015-10-31

    We propose a scheme of a quantum computer based on nanophotonic elements: two buses in the form of nanowaveguide resonators, two nanosized units of multiatom multiqubit quantum memory and a set of nanoprocessors in the form of photonic quantum transistors, each containing a pair of nanowaveguide ring resonators coupled via a quantum dot. The operation modes of nanoprocessor photonic quantum transistors are theoretically studied and the execution of main logical operations by means of them is demonstrated. We also discuss the prospects of the proposed nanophotonic quantum computer for operating in high-speed optical fibre networks. (quantum computations)

  9. Assessment of Clinical Competence: Written and Computer-Based Simulations.

    Science.gov (United States)

    Swanson, David B.; And Others

    1987-01-01

    Literature concerning the validity and reliability of both written and computer-based simulations in assessing clinical competence in the health professions is reviewed, and suggestions are given for the improvement of the psychometric qualities of simulation-based tests. (MSE)

  10. The Mediated Museum: Computer-Based Technology and Museum Infrastructure.

    Science.gov (United States)

    Sterman, Nanette T.; Allen, Brockenbrough S.

    1991-01-01

    Describes the use of computer-based tools and techniques in museums. The integration of realia with media-based advice and interpretation is described, electronic replicas of ancient Greek vases in the J. Paul Getty Museum are explained, examples of mediated exhibits are presented, and the use of hypermedia is discussed. (five references) (LRW)

  11. Pervasive Computing Location-aware Model Based on Ontology

    Institute of Scientific and Technical Information of China (English)

    PU Fang; CAI Hai-bin; CAO Qi-ying; SUN Dao-qing; LI Tong

    2008-01-01

    In order to integrate heterogeneous location-aware systems into pervasive computing environment, a novel pervasive computing location-aware model based on ontology is presented. A location-aware model ontology (LMO) is constructed. The location-aware model has the capabilities of sharing knowledge, reasoning and adjusting the usage policies of services dynamically through a unified semantic location manner. At last, the work process of our proposed location-aware model is explained by an application scenario.

  12. Data Mining Based on Cloud-Computing Technology

    Directory of Open Access Journals (Sweden)

    Ren Ying

    2016-01-01

    Full Text Available There are performance bottlenecks and scalability problems when traditional data-mining system is used in cloud computing. In this paper, we present a data-mining platform based on cloud computing. Compared with a traditional data mining system, this platform is highly scalable, has massive data processing capacities, is service-oriented, and has low hardware cost. This platform can support the design and applications of a wide range of distributed data-mining systems.

  13. Cluster-based localization and tracking in ubiquitous computing systems

    CERN Document Server

    Martínez-de Dios, José Ramiro; Torres-González, Arturo; Ollero, Anibal

    2017-01-01

    Localization and tracking are key functionalities in ubiquitous computing systems and techniques. In recent years a very high variety of approaches, sensors and techniques for indoor and GPS-denied environments have been developed. This book briefly summarizes the current state of the art in localization and tracking in ubiquitous computing systems focusing on cluster-based schemes. Additionally, existing techniques for measurement integration, node inclusion/exclusion and cluster head selection are also described in this book.

  14. Moment Matrices, Border Bases and Real Radical Computation

    OpenAIRE

    Lasserre, Jean-Bernard; Laurent, Monique; Mourrain, Bernard; Rostalski, Philipp; Trébuchet, Philippe

    2013-01-01

    International audience; In this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is finite. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and semi-definite programming. While the border basis algorithms of [17] are efficient and numerically stable for computing complex roots, algorithms based on moment matrices [12] allow the incorpora...

  15. Exchange interactions and Tc in rhenium-doped silicon: DFT, DFT + U and Monte Carlo calculations.

    Science.gov (United States)

    Wierzbowska, Małgorzata

    2012-03-28

    Interactions between rhenium impurities in silicon are investigated by means of the density functional theory (DFT) and the DFT + U scheme. All couplings between impurities are ferromagnetic except the Re-Re dimers which in the DFT method are nonmagnetic, due to the formation of the chemical bond supported by substantial relaxation of the geometry. The critical temperature is calculated by means of classical Monte Carlo (MC) simulations with the Heisenberg Hamiltonian. The uniform ferromagnetic phase is obtained with the DFT exchange interactions at room temperature for the impurities concentration of 7%. With the DFT + U exchange interactions, the ferromagnetic clusters form above room temperature in MC samples containing only 3% Re.

  16. Establishing performance requirements of computer based systems subject to uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, D.

    1997-02-01

    An organized systems design approach is dictated by the increasing complexity of computer based systems. Computer based systems are unique in many respects but share many of the same problems that have plagued design engineers for decades. The design of complex systems is difficult at best, but as a design becomes intensively dependent on the computer processing of external and internal information, the design process quickly borders chaos. This situation is exacerbated with the requirement that these systems operate with a minimal quantity of information, generally corrupted by noise, regarding the current state of the system. Establishing performance requirements for such systems is particularly difficult. This paper briefly sketches a general systems design approach with emphasis on the design of computer based decision processing systems subject to parameter and environmental variation. The approach will be demonstrated with application to an on-board diagnostic (OBD) system for automotive emissions systems now mandated by the state of California and the Federal Clean Air Act. The emphasis is on an approach for establishing probabilistically based performance requirements for computer based systems.

  17. Designing for learner engagement with computer-based testing

    Directory of Open Access Journals (Sweden)

    Richard Walker

    2016-12-01

    Full Text Available The issues influencing student engagement with high-stakes computer-based exams were investigated, drawing on feedback from two cohorts of international MA Education students encountering this assessment method for the first time. Qualitative data from surveys and focus groups on the students’ examination experience were analysed, leading to the identification of engagement issues in the delivery of high-stakes computer-based assessments.The exam combined short-answer open-response questions with multiple-choice-style items to assess knowledge and understanding of research methods. The findings suggest that engagement with computer-based testing depends, to a lesser extent, on students’ general levels of digital literacy and, to a greater extent, on their information technology (IT proficiency for assessment and their ability to adapt their test-taking strategies, including organisational and cognitive strategies, to the online assessment environment. The socialisation and preparation of students for computer-based testing therefore emerge as key responsibilities for instructors to address, with students requesting increased opportunities for practice and training to develop the IT skills and test-taking strategies necessary to succeed in computer-based examinations. These findings and their implications in terms of instructional responsibilities form the basis of a proposal for a framework for Learner Engagement with e-Assessment Practices.

  18. Molecular structure and vibrational and chemical shift assignments of 3'-chloro-4-dimethylamino azobenzene by DFT calculations.

    Science.gov (United States)

    Toy, Mehmet; Tanak, Hasan

    2016-01-05

    In the present work, a combined experimental and theoretical study on ground state molecular structure, spectroscopic and nonlinear optical properties of azo compound 3'-chloro-4-dimethlamino azobenzene are reported. The molecular geometry, vibrational wavenumbers and the first order hyperpolarizability of the title compound were calculated with the help of density functional theory computations. The optimized geometric parameters obtained by using DFT (B3LYP/6-311++G(d,p)) show good agreement with the experimental data. The vibrational transitions were identified based on the recorded FT-IR spectra in the range of 4000-400cm(-1) for solid state. The (1)H isotropic chemical shifts with respect to TMS were also calculated using the gauge independent atomic orbital (GIAO) method and compared with the experimental data. Using the TD-DFT method, electronic absorption spectra of the title compound have been predicted, and good agreement is determined with the experimental ones. To investigate the NLO properties of the title compound, the polarizability and the first hyperpolarizability were calculated using the density functional B3LYP method with the 6-311++G(d,p) basis set. According to results, the title compound exhibits non-zero first hyperpolarizability value revealing second order NLO behavior. In addition, DFT calculations of the title compound, molecular electrostatic potential and frontier molecular orbitals were also performed at 6-311++G(d,p) level of theory.

  19. Molecular structure and vibrational and chemical shift assignments of 3‧-chloro-4-dimethylamino azobenzene by DFT calculations

    Science.gov (United States)

    Toy, Mehmet; Tanak, Hasan

    2016-01-01

    In the present work, a combined experimental and theoretical study on ground state molecular structure, spectroscopic and nonlinear optical properties of azo compound 3‧-chloro-4-dimethlamino azobenzene are reported. The molecular geometry, vibrational wavenumbers and the first order hyperpolarizability of the title compound were calculated with the help of density functional theory computations. The optimized geometric parameters obtained by using DFT (B3LYP/6-311++G(d,p)) show good agreement with the experimental data. The vibrational transitions were identified based on the recorded FT-IR spectra in the range of 4000-400 cm-1 for solid state. The 1H isotropic chemical shifts with respect to TMS were also calculated using the gauge independent atomic orbital (GIAO) method and compared with the experimental data. Using the TD-DFT method, electronic absorption spectra of the title compound have been predicted, and good agreement is determined with the experimental ones. To investigate the NLO properties of the title compound, the polarizability and the first hyperpolarizability were calculated using the density functional B3LYP method with the 6-311++G(d,p) basis set. According to results, the title compound exhibits non-zero first hyperpolarizability value revealing second order NLO behavior. In addition, DFT calculations of the title compound, molecular electrostatic potential and frontier molecular orbitals were also performed at 6-311++G(d,p) level of theory.

  20. Development of tight-binding based GW algorithm and its computational implementation for graphene

    Energy Technology Data Exchange (ETDEWEB)

    Majidi, Muhammad Aziz [Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); NUSNNI-NanoCore, Department of Physics, National University of Singapore (NUS), Singapore 117576 (Singapore); Singapore Synchrotron Light Source (SSLS), National University of Singapore (NUS), 5 Research Link, Singapore 117603 (Singapore); Naradipa, Muhammad Avicenna, E-mail: muhammad.avicenna11@ui.ac.id; Phan, Wileam Yonatan; Syahroni, Ahmad [Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Rusydi, Andrivo [NUSNNI-NanoCore, Department of Physics, National University of Singapore (NUS), Singapore 117576 (Singapore); Singapore Synchrotron Light Source (SSLS), National University of Singapore (NUS), 5 Research Link, Singapore 117603 (Singapore)

    2016-04-19

    Graphene has been a hot subject of research in the last decade as it holds a promise for various applications. One interesting issue is whether or not graphene should be classified into a strongly or weakly correlated system, as the optical properties may change upon several factors, such as the substrate, voltage bias, adatoms, etc. As the Coulomb repulsive interactions among electrons can generate the correlation effects that may modify the single-particle spectra (density of states) and the two-particle spectra (optical conductivity) of graphene, we aim to explore such interactions in this study. The understanding of such correlation effects is important because eventually they play an important role in inducing the effective attractive interactions between electrons and holes that bind them into excitons. We do this study theoretically by developing a GW method implemented on the basis of the tight-binding (TB) model Hamiltonian. Unlike the well-known GW method developed within density functional theory (DFT) framework, our TB-based GW implementation may serve as an alternative technique suitable for systems which Hamiltonian is to be constructed through a tight-binding based or similar models. This study includes theoretical formulation of the Green’s function G, the renormalized interaction function W from random phase approximation (RPA), and the corresponding self energy derived from Feynman diagrams, as well as the development of the algorithm to compute those quantities. As an evaluation of the method, we perform calculations of the density of states and the optical conductivity of graphene, and analyze the results.

  1. DFT-Based Explanation of the Effect of Simple Anionic Ligands on the Regioselectivity of the Heck Arylation of Acrolein Acetals

    DEFF Research Database (Denmark)

    Henriksen, Signe Teuber; Tanner, David Ackland; Cacchi, Sandro

    2009-01-01

    The Heck arylation of acrolein acetal has been studied computationally and compared to the corresponding reaction with allyl ethers. The reaction can be controlled to give either cinnamaldehydes or arylpropanoic esters by addition of different coordinating anions, acetate, or chloride. The comput...... reaction conditions. The difference between the two substrate classes could be rationalized in terms of relative hydride donating power of the two substrates....

  2. Moment Matrices, Border Bases and Real Radical Computation

    CERN Document Server

    Lasserre, Jean-Bernard; Mourrain, Bernard; Rostalki, Philipp; Trébuchet, Philippe

    2011-01-01

    In this paper, we describe new methods to compute the radical (resp. real radical) of an ideal, assuming it complex (resp. real) variety is finite. The aim is to combine approaches for solving a system of polynomial equations with dual methods which involve moment matrices and semi-definite programming. While the border basis algorithms of [17] are efficient and numerically stable for computing complex roots, algorithms based on moment matrices [12] allow the incorporation of additional polynomials, e.g., to re- strict the computation to real roots or to eliminate multiple solutions. The proposed algorithm can be used to compute a border basis of the input ideal and, as opposed to other approaches, it can also compute the quotient structure of the (real) radical ideal directly, i.e., without prior algebraic techniques such as Gr\\"obner bases. It thus combines the strength of existing algorithms and provides a unified treatment for the computation of border bases for the ideal, the radical ideal and the real r...

  3. Identifying systematic DFT errors in catalytic reactions

    DEFF Research Database (Denmark)

    Christensen, Rune; Hansen, Heine Anton; Vegge, Tejs

    2015-01-01

    Using CO2 reduction reactions as examples, we present a widely applicable method for identifying the main source of errors in density functional theory (DFT) calculations. The method has broad applications for error correction in DFT calculations in general, as it relies on the dependence...

  4. Structural Investigation of Methanol {6-[(2-oxidopropyliminomethyl] phenolato} dioxidomolybdenum(VI by X-Ray Crystallography and DFT Calculations

    Directory of Open Access Journals (Sweden)

    Iran SHEIKHSHOAIE

    2012-09-01

    Full Text Available This article presents the computational calculations of a cis-dioxomolybdenum(VI complex by using density functional theory (DFT with a DZP basis set (double zeta polarized basis set. The Schiff base 2-((E-(2-hydroxypropyliminomethyl-6-methoxyphenol was treated with MoO2(acac2 in dry methanol to produce the mononuclear complex methanol{2-methoxy-6-[(2-oxidopropyl iminomethyl]phenolato} dioxidomolybdenum(VI, whose structure has been solved and successfully refined in the monoclinic space group P21/c, with a = 6.755 Å, b = 15.835 Å, c = 13.119 Å, V = 1388.79 Å3, and Z = 4.

  5. Ensemble DFT Approach to Excited States of Strongly Correlated Molecular Systems.

    Science.gov (United States)

    Filatov, Michael

    2016-01-01

    Ensemble density functional theory (DFT) is a novel time-independent formalism for obtaining excitation energies of many-body fermionic systems. A considerable advantage of ensemble DFT over the more common Kohn-Sham (KS) DFT and time-dependent DFT formalisms is that it enables one to account for strong non-dynamic electron correlation in the ground and excited states of molecular systems in a transparent and accurate fashion. Despite its positive aspects, ensemble DFT has not so far found its way into the repertoire of methods of modern computational chemistry, probably because of the perceived lack of practically affordable implementations of the theory. The spin-restricted ensemble-referenced KS (REKS) method is perhaps the first computationally feasible implementation of the ideas behind ensemble DFT which enables one to describe accurately electronic transitions in a wide class of molecular systems, including strongly correlated molecules (biradicals, molecules undergoing bond breaking/formation), extended π-conjugated systems, donor-acceptor charge transfer adducts, etc.

  6. The Validation of Computer-based Models in Engineering: Some Lessons from Computing Science

    Directory of Open Access Journals (Sweden)

    D. J. Murray-Smith

    2001-01-01

    Full Text Available Questions of the quality of computer-based models and the formal processes of model testing, involving internal verification and external validation, are usually given only passing attention in engineering reports and in technical publications. However, such models frequently provide a basis for analysis methods, design calculations or real-time decision-making in complex engineering systems. This paper reviews techniques used for external validation of computer-based models and contrasts the somewhat casual approach which is usually adopted in this field with the more formal approaches to software testing and documentation recommended for large software projects. Both activities require intimate knowledge of the intended application, a systematic approach and considerable expertise and ingenuity in the design of tests. It is concluded that engineering degree courses dealing with modelling techniques and computer simulation should put more emphasis on model limitations, testing and validation.

  7. DFT Study on One-carbon Unit Transfer from 1,10-CH+-tetrahydroquinoxaline to Methylamine

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Density Funetional Theory (DFT) method was used in this paper to study one-carbon transfer from 1.10-tetrahydroquinoxalinc, an analoguc of tetrahydrofolic aeid, to methylamine.This reaetion can be completedvia two paths. From the computation result we can conclude thai a general-aeid catalysis exists in this reaction. By computation we find DFT has its limitation in deseribing a newly incorporated structure with a unit charge.

  8. An Expert Fitness Diagnosis System Based on Elastic Cloud Computing

    Directory of Open Access Journals (Sweden)

    Kevin C. Tseng

    2014-01-01

    Full Text Available This paper presents an expert diagnosis system based on cloud computing. It classifies a user’s fitness level based on supervised machine learning techniques. This system is able to learn and make customized diagnoses according to the user’s physiological data, such as age, gender, and body mass index (BMI. In addition, an elastic algorithm based on Poisson distribution is presented to allocate computation resources dynamically. It predicts the required resources in the future according to the exponential moving average of past observations. The experimental results show that Naïve Bayes is the best classifier with the highest accuracy (90.8% and that the elastic algorithm is able to capture tightly the trend of requests generated from the Internet and thus assign corresponding computation resources to ensure the quality of service.

  9. An Expert Fitness Diagnosis System Based on Elastic Cloud Computing

    Science.gov (United States)

    Tseng, Kevin C.; Wu, Chia-Chuan

    2014-01-01

    This paper presents an expert diagnosis system based on cloud computing. It classifies a user's fitness level based on supervised machine learning techniques. This system is able to learn and make customized diagnoses according to the user's physiological data, such as age, gender, and body mass index (BMI). In addition, an elastic algorithm based on Poisson distribution is presented to allocate computation resources dynamically. It predicts the required resources in the future according to the exponential moving average of past observations. The experimental results show that Naïve Bayes is the best classifier with the highest accuracy (90.8%) and that the elastic algorithm is able to capture tightly the trend of requests generated from the Internet and thus assign corresponding computation resources to ensure the quality of service. PMID:24723842

  10. Computer-aided design–computer-aided engineering associative feature-based heterogeneous object modeling

    Directory of Open Access Journals (Sweden)

    Jikai Liu

    2015-12-01

    Full Text Available Conventionally, heterogeneous object modeling methods paid limited attention to the concurrent modeling of geometry design and material composition distribution. Procedural method was normally employed to generate the geometry first and then determine the heterogeneous material distribution, which ignores the mutual influence. Additionally, limited capability has been established about irregular material composition distribution modeling with strong local discontinuities. This article overcomes these limitations by developing the computer-aided design–computer-aided engineering associative feature-based heterogeneous object modeling method. Level set functions are applied to model the geometry within computer-aided design module, which enables complex geometry modeling. Finite element mesh is applied to store the local material compositions within computer-aided engineering module, which allows any local discontinuities. Then, the associative feature concept builds the correspondence relationship between these modules. Additionally, the level set geometry and material optimization method are developed to concurrently generate the geometry and material information which fills the contents of the computer-aided design–computer-aided engineering associative feature model. Micro-geometry is investigated as well, instead of only the local material composition. A few cases are studied to prove the effectiveness of this new heterogeneous object modeling method.

  11. Computer Literacy and the Construct Validity of a High-Stakes Computer-Based Writing Assessment

    Science.gov (United States)

    Jin, Yan; Yan, Ming

    2017-01-01

    One major threat to validity in high-stakes testing is construct-irrelevant variance. In this study we explored whether the transition from a paper-and-pencil to a computer-based test mode in a high-stakes test in China, the College English Test, has brought about variance irrelevant to the construct being assessed in this test. Analyses of the…

  12. A novel bit-quad-based Euler number computing algorithm

    OpenAIRE

    Yao, Bin; He, Lifeng; Kang, Shiying; Chao, Yuyan; Xiao ZHAO

    2015-01-01

    The Euler number of a binary image is an important topological property in computer vision and pattern recognition. This paper proposes a novel bit-quad-based Euler number computing algorithm. Based on graph theory and analysis on bit-quad patterns, our algorithm only needs to count two bit-quad patterns. Moreover, by use of the information obtained during processing the previous bit-quad, the average number of pixels to be checked for processing a bit-quad is only 1.75. Experimental results ...

  13. A Separated Domain-Based Kernel Model for Trusted Computing

    Institute of Scientific and Technical Information of China (English)

    FANG Yanxiang; SHEN Changxiang; XU Jingdong; WU Gongyi

    2006-01-01

    This paper fist gives an investigation on trusted computing on mainstream operation system (OS). Based on the observations, it is pointed out that Trusted Computing cannot be achieved due to the lack of separation mechanism of the components in mainstream OS. In order to provide a kind of separation mechanism, this paper proposes a separated domain-based kernel model (SDBKM), and this model is verified by non-interference theory. By monitoring and simplifying the trust dependence between domains, this model can solve problems in trust measurement such as deny of service (DoS) attack, Host security, and reduce the overhead of measurement.

  14. Machine learning based Intelligent cognitive network using fog computing

    Science.gov (United States)

    Lu, Jingyang; Li, Lun; Chen, Genshe; Shen, Dan; Pham, Khanh; Blasch, Erik

    2017-05-01

    In this paper, a Cognitive Radio Network (CRN) based on artificial intelligence is proposed to distribute the limited radio spectrum resources more efficiently. The CRN framework can analyze the time-sensitive signal data close to the signal source using fog computing with different types of machine learning techniques. Depending on the computational capabilities of the fog nodes, different features and machine learning techniques are chosen to optimize spectrum allocation. Also, the computing nodes send the periodic signal summary which is much smaller than the original signal to the cloud so that the overall system spectrum source allocation strategies are dynamically updated. Applying fog computing, the system is more adaptive to the local environment and robust to spectrum changes. As most of the signal data is processed at the fog level, it further strengthens the system security by reducing the communication burden of the communications network.

  15. Remote Sensing Image Deblurring Based on Grid Computation

    Institute of Scientific and Technical Information of China (English)

    LI Sheng-yang; ZHU Chong-guang; GE Ping-ju

    2006-01-01

    In general, there is a demand for real-time processing of mass quantity remote sensing images. However, the task is not only data-intensive but also computating-intensive. Distributed processing is a hot topic in remote sensing processing and image deblurring is also one of the most important needs. In order to satisfy the demand for quick processing and deblurring of mass quantity satellite images, we developed a distributed, grid computation-based platform as well as a corresponding middleware for grid computation. Both a constrained power spectrum equalization algorithm and effective block processing measures, which can avoid boundary effect, were applied during the processing. The result is satisfactory since computation efficiency and visual effect were greatly improved. It can be concluded that the technology of spatial information grids is effective for mass quantity remote sensing image processing.

  16. GPU-based high-performance computing for radiation therapy.

    Science.gov (United States)

    Jia, Xun; Ziegenhein, Peter; Jiang, Steve B

    2014-02-21

    Recent developments in radiotherapy therapy demand high computation powers to solve challenging problems in a timely fashion in a clinical environment. The graphics processing unit (GPU), as an emerging high-performance computing platform, has been introduced to radiotherapy. It is particularly attractive due to its high computational power, small size, and low cost for facility deployment and maintenance. Over the past few years, GPU-based high-performance computing in radiotherapy has experienced rapid developments. A tremendous amount of study has been conducted, in which large acceleration factors compared with the conventional CPU platform have been observed. In this paper, we will first give a brief introduction to the GPU hardware structure and programming model. We will then review the current applications of GPU in major imaging-related and therapy-related problems encountered in radiotherapy. A comparison of GPU with other platforms will also be presented.

  17. Entanglement-based machine learning on a quantum computer.

    Science.gov (United States)

    Cai, X-D; Wu, D; Su, Z-E; Chen, M-C; Wang, X-L; Li, Li; Liu, N-L; Lu, C-Y; Pan, J-W

    2015-03-20

    Machine learning, a branch of artificial intelligence, learns from previous experience to optimize performance, which is ubiquitous in various fields such as computer sciences, financial analysis, robotics, and bioinformatics. A challenge is that machine learning with the rapidly growing "big data" could become intractable for classical computers. Recently, quantum machine learning algorithms [Lloyd, Mohseni, and Rebentrost, arXiv.1307.0411] were proposed which could offer an exponential speedup over classical algorithms. Here, we report the first experimental entanglement-based classification of two-, four-, and eight-dimensional vectors to different clusters using a small-scale photonic quantum computer, which are then used to implement supervised and unsupervised machine learning. The results demonstrate the working principle of using quantum computers to manipulate and classify high-dimensional vectors, the core mathematical routine in machine learning. The method can, in principle, be scaled to larger numbers of qubits, and may provide a new route to accelerate machine learning.

  18. Using DFT methodology for more reliable predictive models: Design of inhibitors of Golgi α-Mannosidase II.

    Science.gov (United States)

    Bobovská, Adela; Tvaroška, Igor; Kóňa, Juraj

    2016-05-01

    Human Golgi α-mannosidase II (GMII), a zinc ion co-factor dependent glycoside hydrolase (E.C.3.2.1.114), is a pharmaceutical target for the design of inhibitors with anti-cancer activity. The discovery of an effective inhibitor is complicated by the fact that all known potent inhibitors of GMII are involved in unwanted co-inhibition with lysosomal α-mannosidase (LMan, E.C.3.2.1.24), a relative to GMII. Routine empirical QSAR models for both GMII and LMan did not work with a required accuracy. Therefore, we have developed a fast computational protocol to build predictive models combining interaction energy descriptors from an empirical docking scoring function (Glide-Schrödinger), Linear Interaction Energy (LIE) method, and quantum mechanical density functional theory (QM-DFT) calculations. The QSAR models were built and validated with a library of structurally diverse GMII and LMan inhibitors and non-active compounds. A critical role of QM-DFT descriptors for the more accurate prediction abilities of the models is demonstrated. The predictive ability of the models was significantly improved when going from the empirical docking scoring function to mixed empirical-QM-DFT QSAR models (Q(2)=0.78-0.86 when cross-validation procedures were carried out; and R(2)=0.81-0.83 for a testing set). The average error for the predicted ΔGbind decreased to 0.8-1.1kcalmol(-1). Also, 76-80% of non-active compounds were successfully filtered out from GMII and LMan inhibitors. The QSAR models with the fragmented QM-DFT descriptors may find a useful application in structure-based drug design where pure empirical and force field methods reached their limits and where quantum mechanics effects are critical for ligand-receptor interactions. The optimized models will apply in lead optimization processes for GMII drug developments.

  19. Internet messenger based smart virtual class learning using ubiquitous computing

    Science.gov (United States)

    Umam, K.; Mardi, S. N. S.; Hariadi, M.

    2017-06-01

    Internet messenger (IM) has become an important educational technology component in college education, IM makes it possible for students to engage in learning and collaborating at smart virtual class learning (SVCL) using ubiquitous computing. However, the model of IM-based smart virtual class learning using ubiquitous computing and empirical evidence that would favor a broad application to improve engagement and behavior are still limited. In addition, the expectation that IM based SVCL using ubiquitous computing could improve engagement and behavior on smart class cannot be confirmed because the majority of the reviewed studies followed instructions paradigms. This article aims to present the model of IM-based SVCL using ubiquitous computing and showing learners’ experiences in improved engagement and behavior for learner-learner and learner-lecturer interactions. The method applied in this paper includes design process and quantitative analysis techniques, with the purpose of identifying scenarios of ubiquitous computing and realize the impressions of learners and lecturers about engagement and behavior aspect and its contribution to learning

  20. A Research Roadmap for Computation-Based Human Reliability Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Boring, Ronald [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Joe, Jeffrey [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Groth, Katrina [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    The United States (U.S.) Department of Energy (DOE) is sponsoring research through the Light Water Reactor Sustainability (LWRS) program to extend the life of the currently operating fleet of commercial nuclear power plants. The Risk Informed Safety Margin Characterization (RISMC) research pathway within LWRS looks at ways to maintain and improve the safety margins of these plants. The RISMC pathway includes significant developments in the area of thermalhydraulics code modeling and the development of tools to facilitate dynamic probabilistic risk assessment (PRA). PRA is primarily concerned with the risk of hardware systems at the plant; yet, hardware reliability is often secondary in overall risk significance to human errors that can trigger or compound undesirable events at the plant. This report highlights ongoing efforts to develop a computation-based approach to human reliability analysis (HRA). This computation-based approach differs from existing static and dynamic HRA approaches in that it: (i) interfaces with a dynamic computation engine that includes a full scope plant model, and (ii) interfaces with a PRA software toolset. The computation-based HRA approach presented in this report is called the Human Unimodels for Nuclear Technology to Enhance Reliability (HUNTER) and incorporates in a hybrid fashion elements of existing HRA methods to interface with new computational tools developed under the RISMC pathway. The goal of this research effort is to model human performance more accurately than existing approaches, thereby minimizing modeling uncertainty found in current plant risk models.

  1. Linearized Aeroelastic Computations in the Frequency Domain Based on Computational Fluid Dynamics

    CERN Document Server

    Amsallem, David; Choi, Youngsoo; Farhat, Charbel

    2015-01-01

    An iterative, CFD-based approach for aeroelastic computations in the frequency domain is presented. The method relies on a linearized formulation of the aeroelastic problem and a fixed-point iteration approach and enables the computation of the eigenproperties of each of the wet aeroelastic eigenmodes. Numerical experiments on the aeroelastic analysis and design optimization of two wing configurations illustrate the capability of the method for the fast and accurate aeroelastic analysis of aircraft configurations and its advantage over classical time-domain approaches.

  2. Evaluation of Computer Based Testing in lieu of Regular Examinations in Computer Literacy

    Science.gov (United States)

    Murayama, Koichi

    Because computer based testing (CBT) has many advantages compared with the conventional paper and pencil testing (PPT) examination method, CBT has begun to be used in various situations in Japan, such as in qualifying examinations and in the TOEFL. This paper describes the usefulness and the problems of CBT applied to a regular college examination. The regular computer literacy examinations for first year students were held using CBT, and the results were analyzed. Responses to a questionnaire indicated many students accepted CBT with no unpleasantness and considered CBT a positive factor, improving their motivation to study. CBT also decreased the work of faculty in terms of marking tests and reducing data.

  3. Parallel FFT Algorithm on Computer Clusters

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    DFT is widely applied in the field of signal process and others. Most present rapid ways of calculation are either based on paralleled computers connected by such particular systems like butterfly network, hypercube etc;or based on the assumption of instant transportation, non-conflict communication, complete connection of paralleled processors and unlimited usable processors. However, the delay of communication in the system of information transmission cannot be ignored. This paper works on the following aspects: instant transmission, dispatching missions, and the path of information through the communication link in the computer cluster systems;layout of the dynamic FFT algorithm under the different structures of computer clusters.

  4. An E-learning System based on Affective Computing

    Science.gov (United States)

    Duo, Sun; Song, Lu Xue

    In recent years, e-learning as a learning system is very popular. But the current e-learning systems cannot instruct students effectively since they do not consider the emotional state in the context of instruction. The emergence of the theory about "Affective computing" can solve this question. It can make the computer's intelligence no longer be a pure cognitive one. In this paper, we construct an emotional intelligent e-learning system based on "Affective computing". A dimensional model is put forward to recognize and analyze the student's emotion state and a virtual teacher's avatar is offered to regulate student's learning psychology with consideration of teaching style based on his personality trait. A "man-to-man" learning environment is built to simulate the traditional classroom's pedagogy in the system.

  5. A Computationally Based Approach to Homogenizing Advanced Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jablonski, P D; Cowen, C J

    2011-02-27

    We have developed a computationally based approach to optimizing the homogenization heat treatment of complex alloys. The Scheil module within the Thermo-Calc software is used to predict the as-cast segregation present within alloys, and DICTRA (Diffusion Controlled TRAnsformations) is used to model the homogenization kinetics as a function of time, temperature and microstructural scale. We will discuss this approach as it is applied to both Ni based superalloys as well as the more complex (computationally) case of alloys that solidify with more than one matrix phase as a result of segregation. Such is the case typically observed in martensitic steels. With these alloys it is doubly important to homogenize them correctly, especially at the laboratory scale, since they are austenitic at high temperature and thus constituent elements will diffuse slowly. The computationally designed heat treatment and the subsequent verification real castings are presented.

  6. Formalization for Granular Computing Based on Logical Formulas

    Institute of Scientific and Technical Information of China (English)

    Lin Yan; Qing Liu

    2006-01-01

    In order to make formalization for granular computing, some kinds of formulas are constructed on a universe by a logical method. Every formula expresses a property, and can separate a semantic set which consists of all of the objects satisfying the formula. Therefore a granular space on the universe is produced based on the formulas,and the semantic sets separated by the formulas are taken as a formal definition for granules ,and are called abstract granules. Furthermore, it is proved that any specific granule from an extended mathematical system can be formalized into an abstract granule ,the conclusions is obtained that specific granules from approximate spaces and information systems can also be formalized into abstract granules. Based on a granular space and abstract granules, granular computing is defined, which finally realizes the goal of formalization for granular computing.

  7. A Security Kernel Architecture Based Trusted Computing Platform

    Institute of Scientific and Technical Information of China (English)

    CHEN You-lei; SHEN Chang-xiang

    2005-01-01

    A security kernel architecture built on trusted computing platform in the light of thinking about trusted computing is presented. According to this architecture, a new security module TCB (Trusted Computing Base) is added to the operation system kernel and two operation interface modes are provided for the sake of self-protection. The security kernel is divided into two parts and trusted mechanism is separated from security functionality. The TCB module implements the trusted mechanism such as measurement and attestation,while the other components of security kernel provide security functionality based on these mechanisms. This architecture takes full advantage of functions provided by trusted platform and clearly defines the security perimeter of TCB so as to assure self-security from architectural vision. We also present function description of TCB and discuss the strengths and limitations comparing with other related researches.

  8. Improved Computational Model of Grid Cells Based on Column Structure

    Institute of Scientific and Technical Information of China (English)

    Yang Zhou; Dewei Wu; Weilong Li; Jia Du

    2016-01-01

    To simulate the firing pattern of biological grid cells, this paper presents an improved computational model of grid cells based on column structure. In this model, the displacement along different directions is processed by modulus operation, and the obtained remainder is associated with firing rate of grid cell. Compared with the original model, the improved parts include that: the base of modulus operation is changed, and the firing rate in firing field is encoded by Gaussian⁃like function. Simulation validates that the firing pattern generated by the improved computational model is more consistent with biological characteristic than original model. Besides, the firing pattern is badly influenced by the cumulative positioning error, but the computational model can also generate the regularly hexagonal firing pattern when the real⁃time positioning results are modified.

  9. PHOTOREALISTIC COMPUTER GRAPHICS FORENSICS BASED ON LEADING DIGIT LAW

    Institute of Scientific and Technical Information of China (English)

    Xu Bo; Wang Junwen; Liu Guangjie; Dai Yuewei

    2011-01-01

    As the advent and growing popularity of image rendering software,photorealistic computer graphics are becoming more and more perceptually indistinguishable from photographic images.If the faked images are abused,it may lead to potential social,legal or private consequences.To this end,it is very necessary and also challenging to find effective methods to differentiate between them.In this paper,a novel leading digit law,also called Benford's law,based method to identify computer graphics is proposed.More specifically,statistics of the most significant digits are extracted from image's Discrete Cosine Transform (DCT) coefficients and magnitudes of image's gradient,and then the Support Vector Machine (SVM) based classifiers are built.Results of experiments on the image datasets indicate that the proposed method is comparable to prior works.Besides,it possesses low dimensional features and low computational complexity.

  10. Vibrational spectroscopy [FTIR and FTRaman] investigation, computed vibrational frequency analysis and IR intensity and Raman activity peak resemblance analysis on 4-chloro 2-methylaniline using HF and DFT [LSDA, B3LYP and B3PW91] calculations.

    Science.gov (United States)

    Ramalingam, S; Periandy, S

    2011-03-01

    In the present study, the FT-IR and FT-Raman spectra of 4-chloro-2-methylaniline (4CH2MA) have been recorded in the range of 4000-100 cm(-1). The fundamental modes of vibrational frequencies of 4CH2MA are assigned. All the geometrical parameters have been calculated by HF and DFT (LSDA, B3LYP and B3PW91) methods with 6-31G (d, p) and 6-311G (d, p) basis sets. Optimized geometries of the molecule have been interpreted and compared with the reported experimental values for aniline and some substituted aniline. The harmonic and anharmonic vibrational wavenumbers, IR intensities and Raman activities are calculated at the same theory levels used in geometry optimization. The calculated frequencies are scaled and compared with experimental values. The scaled vibrational frequencies at LSDA/B3LYP/6-311G (d, p) seem to coincide with the experimentally observed values with acceptable deviations. The impact of substitutions on the benzene structure is investigated. The molecular interactions between the substitutions (Cl, CH(3) and NH(2)) are also analyzed.

  11. Molecular structure and computational studies on 2-((2-(4-(3-(2,5-dimethylphenyl)-3-methylcyclobutyl)thiazol-2-yl)hydrazono)methyl)phenol monomer and dimer by DFT calculations

    Science.gov (United States)

    Karakurt, Tuncay; Cukurovali, Alaaddin; Subasi, Nuriye Tuna; Kani, Ibrahim

    2016-12-01

    The title compound, 2-((2-(4-(3-(2,5-Dimethylphenyl)-3-methylcyclobutyl)thiazol-2-yl)hydrazono)methyl)phenol, was characterized by single-crystal X-ray diffraction. In order to calculate molecular geometry along with the infrared, Atoms in Molecules (AIM) analysis and 1H and 13C NMR chemical shift values, the density functional theory (DFT) method with 6-311G++(d,p) basis set was utilized. Experimental data were then used for comparison. While the title crystal structure is photochromic, the molecule is nonplanar. It takes on an enol form including a forceful intramolecular Osbnd H⋯N hydrogen bond as well as a forceful intermolecular Nsbnd H⋯N hydrogen bond. The 6-311G++(d,p) basis function was used to examine the intramolecular tautomerism single proton transfer reaction of the hydrogen-bonded enol-imine and keto-amine monomer in the title crystal structure at the B3LYP theory level. Further, the frontier molecular orbitals (FMO), molecular docking and NLO properties were studied by using theoretical calculations. The calculated NLO properties of title compound are much greater than urea. The title compound generates a stable complex with CDK2 as is distinct from the binding energy values. These results proposed that the compound might exhibit inhibitory effect against CDK2. These are important in development of new antitumor agent.

  12. Computational challenges of structure-based approaches applied to HIV.

    Science.gov (United States)

    Forli, Stefano; Olson, Arthur J

    2015-01-01

    Here, we review some of the opportunities and challenges that we face in computational modeling of HIV therapeutic targets and structural biology, both in terms of methodology development and structure-based drug design (SBDD). Computational methods have provided fundamental support to HIV research since the initial structural studies, helping to unravel details of HIV biology. Computational models have proved to be a powerful tool to analyze and understand the impact of mutations and to overcome their structural and functional influence in drug resistance. With the availability of structural data, in silico experiments have been instrumental in exploiting and improving interactions between drugs and viral targets, such as HIV protease, reverse transcriptase, and integrase. Issues such as viral target dynamics and mutational variability, as well as the role of water and estimates of binding free energy in characterizing ligand interactions, are areas of active computational research. Ever-increasing computational resources and theoretical and algorithmic advances have played a significant role in progress to date, and we envision a continually expanding role for computational methods in our understanding of HIV biology and SBDD in the future.

  13. Cluster based parallel database management system for data intensive computing

    Institute of Scientific and Technical Information of China (English)

    Jianzhong LI; Wei ZHANG

    2009-01-01

    This paper describes a computer-cluster based parallel database management system (DBMS), InfiniteDB, developed by the authors. InfiniteDB aims at efficiently sup-port data intensive computing in response to the rapid grow-ing in database size and the need of high performance ana-lyzing of massive databases. It can be efficiently executed in the computing system composed by thousands of computers such as cloud computing system. It supports the parallelisms of intra-query, inter-query, intra-operation, inter-operation and pipelining. It provides effective strategies for managing massive databases including the multiple data declustering methods, the declustering-aware algorithms for relational operations and other database operations, and the adaptive query optimization method. It also provides the functions of parallel data warehousing and data mining, the coordinator-wrapper mechanism to support the integration of heteroge-neous information resources on the Internet, and the fault tol-erant and resilient infrastructures. It has been used in many applications and has proved quite effective for data intensive computing.

  14. Understanding the spurious DFT fractional charge in the electrochemical double layer

    Science.gov (United States)

    Chen, Leanne; Bajdich, Michal; Luntz, Alan; Chan, Karen; Norskov, Jens

    An ongoing challenge in computational electrochemistry is the accurate determination of electrochemical barriers at constant electrode potential. Recently, our group developed an efficient scheme to determine the barriers using a simple extrapolation based on the interfacial charge. However, semilocal DFT calculations have shown that the magnitude of the charge of solvated species (H3O+, OH-, Li+, Na+) in the outer Helmholtz plane is not 1e, but always near 0.6e, which suggests a charge delocalization error in DFT. Furthermore, we frequently observe inaccurate alignment of the metal Fermi and solvent energy levels. Using an increasing amount of exact exchange, we first analyze the charge delocalization error in the dissociation of NaCl molecule, where a large amount of exchange is need to reproduce the step-like transition of charge from +1 to 0 on the dissociated Na and Cl. Next, we apply the same method to the metal-water interface with solvated ions at varying distances from the surface. The performance of hybrid and other fractional charge-corrected functionals will be discussed together with the possibility of a simple correction scheme.

  15. Synthesis, FTIR, FT-Raman, UV-visible, ab initio and DFT studies on benzohydrazide.

    Science.gov (United States)

    Arjunan, V; Rani, T; Mythili, C V; Mohan, S

    2011-08-01

    A systematic vibrational spectroscopic assignment and analysis of benzohydrazide (BH) has been carried out by using FTIR and FT-Raman spectral data. The vibrational analysis were aided by electronic structure calculations--ab initio (RHF) and hybrid density functional methods (B3LYP and B3PW91) performed with 6-31G(d,p) and 6-311++G(d,p) basis sets. Molecular equilibrium geometries, electronic energies, IR intensities, harmonic vibrational frequencies, depolarization ratios and Raman activities have been computed. Potential energy distribution (PED) and normal mode analysis have also been performed. The assignments proposed based on the experimental IR and Raman spectra have been reviewed and complete assignment of the observed spectra have been proposed. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and λ(max) were determined by time-dependent DFT (TD-DFT) method. The geometrical, thermodynamical parameters and absorption wavelengths were compared with the experimental data. The interactions of carbonyl and hydrazide groups on the benzene ring skeletal modes were investigated. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Simulation of quantum computation : A deterministic event-based approach

    NARCIS (Netherlands)

    Michielsen, K; De Raedt, K; De Raedt, H

    2005-01-01

    We demonstrate that locally connected networks of machines that have primitive learning capabilities can be used to perform a deterministic, event-based simulation of quantum computation. We present simulation results for basic quantum operations such as the Hadamard and the controlled-NOT gate, and

  17. Evaluating Computer-Based Test Accommodations for English Learners

    Science.gov (United States)

    Roohr, Katrina Crotts; Sireci, Stephen G.

    2017-01-01

    Test accommodations for English learners (ELs) are intended to reduce the language barrier and level the playing field, allowing ELs to better demonstrate their true proficiencies. Computer-based accommodations for ELs show promising results for leveling that field while also providing us with additional data to more closely investigate the…

  18. Impact of Computer Based Online Entrepreneurship Distance Education in India

    Science.gov (United States)

    Shree Ram, Bhagwan; Selvaraj, M.

    2012-01-01

    The success of Indian enterprises and professionals in the computer and information technology (CIT) domain during the twenty year has been spectacular. Entrepreneurs, bureaucrats and technocrats are now advancing views about how India can ride CIT bandwagon and leapfrog into a knowledge-based economy in the area of entrepreneurship distance…

  19. The Health of the Computer-Based Patient Record.

    Science.gov (United States)

    Frisse, Mark E.

    1992-01-01

    The newly incorporated Computer-Based Patient Record Institute (CPRI) is discussed in the context of the history of medical records, the need for change (mainly because of health care reimbursement and regulation), and the need for involvement by all medical professionals in the development of standards of data collection which reflect public…

  20. A computer-based registration system for geological collections

    NARCIS (Netherlands)

    Germeraad, J.H.; Freudenthal, M.; Boogaard, van den M.; Arps, C.E.S.

    1972-01-01

    The new computer-based registration system, a project of the National Museum of Geology and Mineralogy in the Netherlands, will considerably increase the accessibility of the Museum collection. This greater access is realized by computerisation of the data in great detail, so that an almost unlimite

  1. Students' Motivation toward Computer-Based Language Learning

    Science.gov (United States)

    Genc, Gulten; Aydin, Selami

    2011-01-01

    The present article examined some factors affecting the motivation level of the preparatory school students in using a web-based computer-assisted language-learning course. The sample group of the study consisted of 126 English-as-a-foreign-language learners at a preparatory school of a state university. After performing statistical analyses…

  2. Interface Design in Computer-Based Language Testing.

    Science.gov (United States)

    Fulcher, Glenn

    2003-01-01

    Describes a three-phase process model for interface design, drawing on practices developed in the software industry and adapting them for computer-based languages tests. Describes good practice in initial design, emphasizes the importance of usability testing, and argues that only through following a principled approach to interface design can the…

  3. pyro: Python-based tutorial for computational methods for hydrodynamics

    Science.gov (United States)

    Zingale, Michael

    2015-07-01

    pyro is a simple python-based tutorial on computational methods for hydrodynamics. It includes 2-d solvers for advection, compressible, incompressible, and low Mach number hydrodynamics, diffusion, and multigrid. It is written with ease of understanding in mind. An extensive set of notes that is part of the Open Astrophysics Bookshelf project provides details of the algorithms.

  4. Status Report on the NBME's Computer-Based Testing.

    Science.gov (United States)

    Clyman, Stephen G.; Orr, Nancy A.

    1990-01-01

    The process proposed for the development and use of computer-based testing, including simulation and multiple-choice questions, as part of the National Board of Medical Examiners' certification sequence is outlined. Summary reports of first-phase pilot testing in six medical schools are appended. (MSE)

  5. Computer-Based Dynamic Assessment of Multidigit Multiplication.

    Science.gov (United States)

    Gerber, Michael M.; And Others

    1994-01-01

    Design details, operation, and initial field test results are reported for DynaMath, a computer-based dynamic assessment system that provides individually tailored, instructionally useful assessment of students with disabilities. DynaMath organizes and outputs student performance data, graphically shows the "zone of proximal…

  6. A Micro-Computer Based Tutor for Teaching Arithmetic Skills.

    Science.gov (United States)

    Attisha, M.; Yazdani, M.

    1983-01-01

    Describes a knowledge-based tutoring system which provides pupil interaction with the microcomputer to diagnose pupils' errors in subtraction operations. Current subtraction methods; nature and origin of subtraction errors; and the structure, achievements, and future developments of the computer system are included. Thirteen references and a…

  7. Computed tomography of the human developing anterior skull base

    NARCIS (Netherlands)

    J. van Loosen (J.); A.I.J. Klooswijk (A. I J); D. van Velzen (D.); C.D.A. Verwoerd (Carel)

    1990-01-01

    markdownabstractAbstract The ossification of the anterior skull base, especially the lamina cribrosa, has been studied by computed tomography and histopathology. Sixteen human fetuses, (referred to our laboratory for pathological examination after spontaneous abortion between 18 and 32 weeks of ge

  8. Marking Strategies in Metacognition-Evaluated Computer-Based Testing

    Science.gov (United States)

    Chen, Li-Ju; Ho, Rong-Guey; Yen, Yung-Chin

    2010-01-01

    This study aimed to explore the effects of marking and metacognition-evaluated feedback (MEF) in computer-based testing (CBT) on student performance and review behavior. Marking is a strategy, in which students place a question mark next to a test item to indicate an uncertain answer. The MEF provided students with feedback on test results…

  9. Secure data structures based on multi-party computation

    DEFF Research Database (Denmark)

    Toft, Tomas

    2011-01-01

    This work considers data structures based on multi-party computation (MPC) primitives: structuring secret (e.g. secret shared and potentially unknown) data such that it can both be queried and updated efficiently. Implementing an oblivious RAM (ORAM) using MPC allows any existing data structure...

  10. Replica-Based High-Performance Tuple Space Computing

    DEFF Research Database (Denmark)

    Andric, Marina; De Nicola, Rocco; Lluch Lafuente, Alberto

    2015-01-01

    We present the tuple-based coordination language RepliKlaim, which enriches Klaim with primitives for replica-aware coordination. Our overall goal is to offer suitable solutions to the challenging problems of data distribution and locality in large-scale high performance computing. In particular,...

  11. Computer-Based Information Services in Medicine: A Feasibility Study.

    Science.gov (United States)

    Cox, P. H.; And Others

    The objectives of this study were to examine the need and potential demand for computer-based information services in the University of Otago medical libraries, to evaluate the various databases of interest, and to recommend the best means of access to such services. Data were collected through user and library surveys, an extensive literature…

  12. THE STRATEGY OF RESOURCE MANAGEMENT BASED ON GRID COMPUTING

    Institute of Scientific and Technical Information of China (English)

    Wang Ruchuan; Han Guangfa; Wang Haiyan

    2006-01-01

    This paper analyzes the defaults of traditional method according to the resource management method of grid computing based on virtual organization. It supports the concept to ameliorate the resource management with mobile agent and gives the ameliorated resource management model. Also pointed out is the methodology of ameliorating resource management and the way to realize in reality.

  13. Improving Computer Based Speech Therapy Using a Fuzzy Expert System

    OpenAIRE

    Ovidiu Andrei Schipor; Stefan Gheorghe Pentiuc; Maria Doina Schipor

    2012-01-01

    In this paper we present our work about Computer Based Speech Therapy systems optimization. We focus especially on using a fuzzy expert system in order to determine specific parameters of personalized therapy, i.e. the number, length and content of training sessions. The efficiency of this new approach was tested during an experiment performed with our CBST, named LOGOMON.

  14. An Intelligent Computer-Based System for Sign Language Tutoring

    Science.gov (United States)

    Ritchings, Tim; Khadragi, Ahmed; Saeb, Magdy

    2012-01-01

    A computer-based system for sign language tutoring has been developed using a low-cost data glove and a software application that processes the movement signals for signs in real-time and uses Pattern Matching techniques to decide if a trainee has closely replicated a teacher's recorded movements. The data glove provides 17 movement signals from…

  15. Content Analysis of a Computer-Based Faculty Activity Repository

    Science.gov (United States)

    Baker-Eveleth, Lori; Stone, Robert W.

    2013-01-01

    The research presents an analysis of faculty opinions regarding the introduction of a new computer-based faculty activity repository (FAR) in a university setting. The qualitative study employs content analysis to better understand the phenomenon underlying these faculty opinions and to augment the findings from a quantitative study. A web-based…

  16. Replication-based Inference Algorithms for Hard Computational Problems

    OpenAIRE

    Alamino, Roberto C.; Neirotti, Juan P.; Saad, David

    2013-01-01

    Inference algorithms based on evolving interactions between replicated solutions are introduced and analyzed on a prototypical NP-hard problem - the capacity of the binary Ising perceptron. The efficiency of the algorithm is examined numerically against that of the parallel tempering algorithm, showing improved performance in terms of the results obtained, computing requirements and simplicity of implementation.

  17. Tree Decomposition based Steiner Tree Computation over Large Graphs

    OpenAIRE

    2013-01-01

    In this paper, we present an exact algorithm for the Steiner tree problem. The algorithm is based on certain pre-computed index structures. Our algorithm offers a practical solution for the Steiner tree problems on graphs of large size and bounded number of terminals.

  18. A self-consistent DFT + DMFT scheme in the projector augmented wave method: applications to cerium, Ce2O3 and Pu2O3 with the Hubbard I solver and comparison to DFT + U.

    Science.gov (United States)

    Amadon, B

    2012-02-22

    An implementation of full self-consistency over the electronic density in the DFT + DMFT framework on the basis of a plane wave–projector augmented wave (PAW) DFT code is presented. It allows for an accurate calculation of the total energy in DFT + DMFT within a plane wave approach. In contrast to frameworks based on the maximally localized Wannier function, the method is easily applied to f electron systems, such as cerium, cerium oxide (Ce2O3) and plutonium oxide (Pu2O3). In order to have a correct and physical calculation of the energy terms, we find that the calculation of the self-consistent density is mandatory. The formalism is general and does not depend on the method used to solve the impurity model. Calculations are carried out within the Hubbard I approximation, which is fast to solve, and gives a good description of strongly correlated insulators. We compare the DFT + DMFT and DFT + U solutions, and underline the qualitative differences of their converged densities. We emphasize that in contrast to DFT + U, DFT + DMFT does not break the spin and orbital symmetry. As a consequence, DFT + DMFT implies, on top of a better physical description of correlated metals and insulators, a reduced occurrence of unphysical metastable solutions in correlated insulators in comparison to DFT + U.

  19. Computer-Based Technologies in Dentistry: Types and Applications

    Directory of Open Access Journals (Sweden)

    Rajaa Mahdi Musawi

    2016-10-01

    Full Text Available During dental education, dental students learn how to examine patients, make diagnosis, plan treatment and perform dental procedures perfectly and efficiently. However, progresses in computer-based technologies including virtual reality (VR simulators, augmented reality (AR and computer aided design/computer aided manufacturing (CAD/CAM systems have resulted in new modalities for instruction and practice of dentistry. Virtual reality dental simulators enable repeated, objective and assessable practice in various controlled situations. Superimposition of three-dimensional (3D virtual images on actual images in AR allows surgeons to simultaneously visualize the surgical site and superimpose informative 3D images of invisible regions on the surgical site to serve as a guide. The use of CAD/CAM systems for designing and manufacturing of dental appliances and prostheses has been well established.This article reviews computer-based technologies, their application in dentistry and their potentials and limitations in promoting dental education, training and practice. Practitioners will be able to choose from a broader spectrum of options in their field of practice by becoming familiar with new modalities of training and practice.Keywords: Virtual Reality Exposure Therapy; Immersion; Computer-Aided Design; Dentistry; Education

  20. Robot Animals Based on Brain-Computer Interface

    Institute of Scientific and Technical Information of China (English)

    Yang Xia; Lei Lei; Tie-Jun Liu; De-Zhong Yao

    2009-01-01

    The study of robot animals based on brain-computer interface (BCI) technology is an important field in robots and neuroscience at present.In this paper,the development status at home and abroad of the motion control of robot based on BCI and principle of robot animals are introduced,then a new animals' behavior control method by photostimulation is presented.At last,the application prospect is provided.