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1

Energy partitioning on intermolecular interactions: ab initio Monte Carlo study of water dimer  

Directory of Open Access Journals (Sweden)

Full Text Available Ab initio Monte Carlo computations were carried out on H2O dimer system. By introducing the energy partitioning scheme that we have developed recently, ab initio calculated H2O-H2O interaction can be analyzed from the viewpoint of atom-atom interaction. The electronic polarization caused by the interaction and its temperature dependence are also discussed. To our best knowledge, this is the first report on the thermal distribution of electronic distortion energy assigned to a molecule.

T.Amano

2007-12-01

2

Hyperspherical representation of potential energy surfaces: intermolecular interactions in tetra-atomic and penta-atomic systems  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we discuss the applications of spherical and hyperspherical harmonics expansions for potential energy surfaces for intermolecular interactions, focusing on four- and five-body problems. Case studies include diatomic-molecule-diatomic-molecule systems, floppy-molecule-rare-gas-atom cases, atom-triatomic, and nonlinear-molecule-linear-molecule systems. Among these systems, the important ones regarding water interaction with atoms and diatomic molecules are presented here to illustrate the use of spherical and hyperspherical coordinates and harmonics for weakly interacting systems. The interaction potential representation involves the distance between the centers of mass of the two molecules and a set of angles that defines the mutual orientation of the molecules, whose geometries are assumed to be either 'frozen' in their equilibrium configurations or to vary according to specific large-amplitude modes. The potential energy surfaces in the given examples of water-hydrogen, nitrogen and oxygen interactions are generated at the CCSD(T)/aug-cc-pVTZ level. Comparisons to the theoretical and experimental results of recent works for these and similar systems are presented.

Barreto, Patricia R P [Instituto Nacional de Pesquisas Espaciais (INPE)/MCT, Laboratorio Associado de Plasma (LAP), Sao Jose dos Campos, SP, CEP 12247-970, CP515 (Brazil); Albernaz, Alessandra F [Instituto de Fisica, Universidade de Brasilia, CP04455, Brasilia, DF, CEP 70919-970 (Brazil); Palazzetti, Federico; Lombardi, Andrea; Grossi, Gaia; Aquilanti, Vincenzo, E-mail: patricia@plasma.inpe.br, E-mail: vincenzo.aquilanti@unipg.it [Dipartimento di Chimica, Universita di Perugia, via Elce di Sotto 8, 06123 Perugia (Italy)

2011-08-01

3

Bowl inversion state controlled by intermolecular interactions  

International Nuclear Information System (INIS)

Full text: Bowl-shaped pi-conjugated compounds are important not only as model compounds of fullerenes but also as possible hosts for different guest molecules. Recent studies regarding the storage of possible energy carriers such as hydrogen and methane in nano-structured carbon materials have further increased the interest in well defined model compounds that allow for a detailed investigation of host-guest interactions in order to optimize the storage capacity of technologically relevant carbon-based materials. Within this context we investigated the structural properties of monolayer films of sumanene (C21H12) deposited on Ag(111). Based on STM experiments we find that the fraction of molecules having a bowl-down adsorption geometry is coverage-dependent, indicating that the bowl-inversion state is determined by intermolecular interactions. The experimental findings are rationalized by density functional theory (DFT) calculations, which reveal a subtle interplay between molecule-substrate and molecule- molecule interactions that is responsible for the abrupt structural change involving inversion of a fraction of the molecules and reorientation of the molecules with respect to the surface normal. (author)

2011-06-15

4

Intermolecular Interactions of Noble-Gas-Containing Species  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The importance of intermolecular interactions to chemistry, physics, and biology is difficult to overestimate. Without intermolecular forces, condensed phase matter could not form. The simplest way to categorize different types of intermolecular interactions is to describe them using van der Waals and hydrogen bonded (H-bonded) interactions. In the H-bond, the intermolecular interaction appears between a positively charged hydrogen atom and electronegative fragments and it originates from str...

Lignell, Antti

2008-01-01

5

An energy decomposition analysis for intermolecular interactions from an absolutely localized molecular orbital reference at the coupled-cluster singles and doubles level  

International Nuclear Information System (INIS)

We propose a wave function-based method for the decomposition of intermolecular interaction energies into chemically-intuitive components, isolating both mean-field- and explicit correlation-level contributions. We begin by solving the locally-projected self-consistent field for molecular interactions equations for a molecular complex, obtaining an intramolecularly polarized reference of self-consistently optimized, absolutely-localized molecular orbitals (ALMOs), determined with the constraint that each fragment MO be composed only of atomic basis functions belonging to its own fragment. As explicit inter-electronic correlation is integral to an accurate description of weak forces underlying intermolecular interaction potentials, namely, coordinated fluctuations in weakly interacting electronic densities, we add dynamical correlation to the ALMO polarized reference at the coupled-cluster singles and doubles level, accounting for explicit dispersion and charge-transfer effects, which map naturally onto the cluster operator. We demonstrate the stability of energy components with basis set extension, follow the hydrogen bond-breaking coordinate in the Cs-symmetry water dimer, decompose the interaction energies of dispersion-bound rare gas dimers and other van der Waals complexes, and examine charge transfer-dominated donor-acceptor interactions in borane adducts. We compare our results with high-level calculations and experiment when possible.

2012-01-14

6

Energy-dispersive NEXAFS. A novel tool for the investigation of intermolecular interaction and structural phase dynamics  

Energy Technology Data Exchange (ETDEWEB)

In the context of this thesis, the novel method soft X-ray energy-dispersive NEXAFS spectroscopy was explored and utilized to investigate intermolecular coupling and post-growth processes with a temporal resolution of seconds. 1,4,5,8- naphthalene tetracarboxylic acid dianhydride (NTCDA)multilayer films were the chosen model system for these investigations. The core hole-electron correlation in coherently coupled molecules was studied by means of energy-dispersive near-edge X-ray absorption fine-structure spectroscopy. A transient phase was found which exists during the transition between a disordered condensed phase and the bulk structure. This phase is characterized by distinct changes in the spectral line shape and energetic position of the X-ray absorption signal at the C K-edge. The findings were explained with the help of theoretical models based on the coupling of transition dipole moments, which are well established for optically excited systems. In consequence, the experimental results provides evidence for a core hole-electron pair delocalized over several molecules. Furthermore, the structure formation of NTCDA multilayer films on Ag(111) surfaces was investigated. With time-resolved and energy-dispersive NEXAFS experiments the intensity evolution in s- and p-polarization showed a very characteristic behavior. By combining these findings with the results of time-dependent photoemission measurements, several sub-processes were identified in the post- growth behavior. Upon annealing, the amorphous but preferentially flat-lying molecules flip into an upright orientation. After that follows a phase characterized by strong intermolecular coupling. Finally, three-dimensional islands are established. Employing the Kolmogorov-Johnson-Mehl-Avrami model, the activation energies of the sub-processes were determined.

Scholz, Markus

2013-06-27

7

Energy-dispersive NEXAFS. A novel tool for the investigation of intermolecular interaction and structural phase dynamics  

International Nuclear Information System (INIS)

In the context of this thesis, the novel method soft X-ray energy-dispersive NEXAFS spectroscopy was explored and utilized to investigate intermolecular coupling and post-growth processes with a temporal resolution of seconds. 1,4,5,8- naphthalene tetracarboxylic acid dianhydride (NTCDA)multilayer films were the chosen model system for these investigations. The core hole-electron correlation in coherently coupled molecules was studied by means of energy-dispersive near-edge X-ray absorption fine-structure spectroscopy. A transient phase was found which exists during the transition between a disordered condensed phase and the bulk structure. This phase is characterized by distinct changes in the spectral line shape and energetic position of the X-ray absorption signal at the C K-edge. The findings were explained with the help of theoretical models based on the coupling of transition dipole moments, which are well established for optically excited systems. In consequence, the experimental results provides evidence for a core hole-electron pair delocalized over several molecules. Furthermore, the structure formation of NTCDA multilayer films on Ag(111) surfaces was investigated. With time-resolved and energy-dispersive NEXAFS experiments the intensity evolution in s- and p-polarization showed a very characteristic behavior. By combining these findings with the results of time-dependent photoemission measurements, several sub-processes were identified in the post- growth behavior. Upon annealing, the amorphous but preferentially flat-lying molecules flip into an upright orientation. After that follows a phase characterized by strong intermolecular coupling. Finally, three-dimensional islands are established. Employing the Kolmogorov-Johnson-Mehl-Avrami model, the activation energies of the sub-processes were determined.

2013-01-01

8

Electronic band structure and intermolecular interaction in substituted thiophene polymorphs  

International Nuclear Information System (INIS)

Total energy calculations based on a density-functional tight-binding scheme have been performed on polymorphic modifications of various thiophene crystals. The electronic band structures exhibit a quasi-one-dimensional interaction in the triclinic crystals, while the monoclinic modifications show no dispersion over the whole Brillouin zone. The main interaction mechanism can be described as a d-? wave function overlap between sulfur and carbon. The strong intermolecular interaction may induce an interchain excitation, responsible for the different optical properties of the polymorphs

2001-06-15

9

Effects of intermolecular interaction on the energy distribution of valance electronic states of a carbazole-based material in amorphous thin films  

Science.gov (United States)

Effects of intermolecular interactions on the occupied electronic structure of amorphous solid of a carbazole-based material were investigated under an assumption that the organic solid consists of randomly oriented assemblies of dimers. The electronic energy states were calculated on the ensemble of large number of random dimers, of which geometries are relaxed using semiempirical van der Waals density functional theory. Intermolecular interactions result in splitting of energy level, and further disorders occur by aggregation of randomly orientated molecules. As a result, frontier occupied energy states can be represented by a superposition of Gaussian distributions, including (i) a main distribution with full width at half maximum of 80-110 meV, depending on the methods of relaxation and (ii) shoulders separated from the center of the main distribution with a value as large as 150 meV. A possible origin for the appearance of these shoulders was ascribed to the presence of molecular assemblies consisting of more tightly bound dimers compared with the others.

Kwon, Soonnam; Wee, Kyung-Ryang; Kim, Jeong Won; Pac, Chyongjin; Kang, Sang Ook

2012-05-01

10

A programmable optimization environment using the GAMESS-US and MERLIN/MCL packages. Applications on intermolecular interaction energies  

Science.gov (United States)

The Merlin/MCL optimization environment and the GAMESS-US package were combined so as to offer an extended and efficient quantum chemistry optimization system, capable of implementing complex optimization strategies for generic molecular modeling problems. A communication and data exchange interface was established between the two packages exploiting all Merlin features such as multiple optimizers, box constraints, user extensions and a high level programming language. An important feature of the interface is its ability to perform dimer computations by eliminating the basis set superposition error using the counterpoise (CP) method of Boys and Bernardi. Furthermore it offers CP-corrected geometry optimizations using analytic derivatives. The unified optimization environment was applied to construct portions of the intermolecular potential energy surface of the weakly bound H-bonded complex C 6H 6-H 2O by utilizing the high level Merlin Control Language. The H-bonded dimer HF-H 2O was also studied by CP-corrected geometry optimization. The ab initio electronic structure energies were calculated using the 6-31G ** basis set at the Restricted Hartree-Fock and second-order Moller-Plesset levels, while all geometry optimizations were carried out using a quasi-Newton algorithm provided by Merlin. Program summaryTitle of program: MERGAM Catalogue identifier:ADYB_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADYB_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer for which the program is designed and others on which it has been tested: The program is designed for machines running the UNIX operating system. It has been tested on the following architectures: IA32 (Linux with gcc/g77 v.3.2.3), AMD64 (Linux with the Portland group compilers v.6.0), SUN64 (SunOS 5.8 with the Sun Workshop compilers v.5.2) and SGI64 (IRIX 6.5 with the MIPSpro compilers v.7.4) Installations: University of Ioannina, Greece Operating systems or monitors under which the program has been tested: UNIX Programming language used: ANSI C, ANSI Fortran-77 No. of lines in distributed program, including test data, etc.:11 282 No. of bytes in distributed program, including test data, etc.: 49 458 Distribution format: tar.gz Memory required to execute with typical data: Memory requirements mainly depend on the selection of a GAMESS-US basis set and the number of atoms No. of bits in a word: 32 No. of processors used: 1 Has the code been vectorized or parallelized?: no Nature of physical problem: Multidimensional geometry optimization is of great importance in any ab initio calculation since it usually is one of the most CPU-intensive tasks, especially on large molecular systems. For example, the geometric and energetic description of van der Waals and weakly bound H-bonded complexes requires the construction of related important portions of the multidimensional intermolecular potential energy surface (IPES). So the various held views about the nature of these bonds can be quantitatively tested. Method of solution: The Merlin/MCL optimization environment was interconnected with the GAMESS-US package to facilitate geometry optimization in quantum chemistry problems. The important portions of the IPES require the capability to program optimization strategies. The Merlin/MCL environment was used for the implementation of such strategies. In this work, a CP-corrected geometry optimization was performed on the HF-H 2O complex and an MCL program was developed to study portions of the potential energy surface of the C 6H 6-H 2O complex. Restrictions on the complexity of the problem: The Merlin optimization environment and the GAMESS-US package must be installed. The MERGAM interface requires GAMESS-US input files that have been constructed in Cartesian coordinates. This restriction occurs from a design-time requirement to not allow reorientation of atomic coordinates; this rule holds always true when applying the COORD = UNIQUE keyword in a GAMESS-US input file. Typical running time: It depends on the size of

Kalatzis, Fanis G.; Papageorgiou, Dimitrios G.; Demetropoulos, Ioannis N.

2006-09-01

11

Learning about Intermolecular Interactions from the Cambridge Structural Database  

Science.gov (United States)

A clear understanding and appreciation of noncovalent interactions, especially hydrogen bonding, are vitally important to students of chemistry and the life sciences, including biochemistry, molecular biology, pharmacology, and medicine. The opportunities afforded by the IsoStar knowledge base of intermolecular interactions to enhance the…

Battle, Gary M.; Allen, Frank H.

2012-01-01

12

He-, Ne-, and Ar-phosgene intermolecular potential energy surfaces  

DEFF Research Database (Denmark)

Using the CCSD(T) model, we evaluated the intermolecular potential energy surfaces of the He-, Ne-, and Ar-phosgene complexes. We considered a representative number of intermolecular geometries for which we calculated the corresponding interaction energies with the augmented (He complex) and double augmented (Ne and Ar complexes) correlation-consistent polarized valence triple-ζ basis sets extended with a set of 3s3p2d1f1g midbond functions. These basis sets were selected after systematic basis set studies carried out at geometries close to those of the surface minima. The He-, Ne-, and Ar-phosgene surfaces were found to have absolute minima of -72.1, -140.4, and -326.6 cm -1 at distances between the rare-gas atom and the phosgene center of mass of 3.184, 3.254, and 3.516 AÌ?, respectively. The potentials were further used in the evaluation of rovibrational states and the rotational constants of the complexes, providing valuable results for future experimental investigations. Comparing our results to those previously available for other phosgene complexes, we suggest that the results for Cl2-phosgene should be revised.

Munteanu, Cristian R.; Henriksen, Christian

2013-01-01

13

Interplay between molecular conformation and intermolecular interactions in conformational polymorphism: a molecular perspective from electronic calculations of tolfenamic acid.  

Science.gov (United States)

Tolfenamic acid exhibits conformational polymorphism. The molecules in its two commonly occurred crystal structures form similar hydrogen-bonded dimers but differ in conformation. The conformational variance was analyzed by electronic calculation methods with the aim to unravel intrinsic connection between the conformational flexibility and intermolecular interactions in the polymorphs. The study was conducted mainly by conceptual density functional theory (DFT) and natural bond orbital (NBO) analysis. It is found that the conformational polymorphism is resulted from the energy competition between intramolecular ?-conjugation and intermolecular hydrogen bonding. By adapting conformation that departs from being the most energetically stable, tolfenamic acid molecules can strengthen the intermolecular hydrogen-bonding interactions in the crystals. The study illustrates how the molecule's electronic properties are influenced by conformational variation and, inherently, how the intermolecular interactions become regulated. Moreover, understanding molecular interaction and crystal packing necessitates electronic structure calculation and analysis, which can be further facilitated by utilizing DFT and NBO concepts. PMID:21570454

Mattei, Alessandra; Li, Tonglei

2011-10-14

14

Intermolecular interactions in electron transfer through stretched helical peptides.  

Science.gov (United States)

The helical peptide Cys-Ala-Lys-(Glu-Ala-Ala-Ala-Lys)(2)-Ala-NH-(CH(2))(2)-SH has been organized forming a self-assembled monolayer on gold (0.602 peptides per nm(2)), its conductance behavior under stretching conditions being studied using scanning tunnelling microscopy and current sensing atomic force microscopy. The helical conformation of the peptide has been found to play a fundamental role in the conductance. Moreover, variation of the current upon molecular stretching indicates that peptides can be significantly elongated before the conductance drops to zero, the critical elongation being 1.22 ± 0.47 nm. Molecular dynamics simulations of a single peptide in the free state and of a variable number of peptides tethered to a gold surface (i.e. densities ranging from 0.026 to 1.295 peptides per nm(2)) have indicated that the helical conformation is intrinsically favored in solvated environments while in desolvated environments it is retained because of the fundamental role played by peptide-peptide intermolecular interactions. The structure obtained for the system with 24 tethered peptides, with a density of 0.634 peptides per nm(2) closest to the experimental one, is in excellent agreement with experimental observations. On the other hand, simulations in which a single molecule is submitted to different compression and stretching processes while the rest remain in the equilibrium have been used to mimic the variation of the tip-substrate distance in experimental measures. Results allowed us to identify the existence, and in some cases coexistence, of intermolecular and intramolecular ionic ladders, suggesting that peptide-mediated electron transfer occurs through the hopping mechanism. Finally, quantum mechanical calculations have been used to investigate the variation of the electronic structure upon compression and stretching deformations. PMID:22735160

López-Pérez, Daniel E; Revilla-López, Guillermo; Jacquemin, Denis; Zanuy, David; Palys, Barbara; Sek, Slawomir; Alemán, Carlos

2012-08-01

15

Intermolecular diatomic energies of a hydrogen dimer with non-Born-Oppenheimer nuclear and electron wave packets  

Science.gov (United States)

We have developed an efficient theoretical framework of a non-Born-Oppenheimer (non-BO) nuclear and electron wave packet (NWP and EWP) method and applied it to intra- and intermolecular energies of a hydrogen dimer. The energy surface functions were derived at low computational cost. In contrast with the ordinary BO nuclear quantization on a given energy surface that reduces the effective barrier, non-trivial non-BO interactions between the EWPs and NWPs resulted in increases of intermolecular rotational and translational barriers. A direct comparison demonstrated that the non-BO effect on the intermolecular energy is significant.

Hyeon-Deuk, Kim; Ando, Koji

2012-04-01

16

New bases for the evaluation of interaction energies: An ab initio study of the CO-Ne van der Waals complex intermolecular potential and ro-vibrational spectrum  

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: CO-Ne IPES. Highlights: {yields} From the LPol, MLPol, and aug-pc-2 bases we obtained new bases for the evaluation of CO-Ne interaction energies. {yields} We checked the bases on the evaluation of the rovibrational spectrum. {yields} The results were satisfactory, being the new bases more efficient than those previously available. - Abstract: Recently we have derived new efficient basis sets for the evaluation of interaction energies in the X-Y (X, Y = He, Ne, Ar) van der Waals complexes. Here we extend the study to the CO-Ne complex. For this, we start with a systematic basis set study, where the LPol, MLPol and Jensen's aug-pc-2 basis sets are considered as starting point (for the Ne atom LPol bases are developed). As reference we take interaction energy results obtained with Dunning's augmented correlation consistent polarized valence basis sets. In all cases we test extensions with different sets of midbond functions. With the selected bases we evaluate CCSD(T) interaction potentials, and to check the potentials further, we obtain the ro-vibrational spectrum of the complex. The results are compared to the available experimental data.

Bouzon Capelo, Silvia [Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials (CIQUS), University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Baranowska-Laczkowska, Angelika [Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials (CIQUS), University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain); Institute of Physics, Kazimierz Wielki University, Plac Weyssenhoffa 11, PL-85072 Bydgoszcz (Poland); Fernandez, Berta, E-mail: berta.fernandez@usc.es [Department of Physical Chemistry and Center for Research in Biological Chemistry and Molecular Materials (CIQUS), University of Santiago de Compostela, E-15782 Santiago de Compostela (Spain)

2011-07-28

17

New bases for the evaluation of interaction energies: An ab initio study of the CO-Ne van der Waals complex intermolecular potential and ro-vibrational spectrum  

International Nuclear Information System (INIS)

Graphical abstract: CO-Ne IPES. Highlights: ? From the LPol, MLPol, and aug-pc-2 bases we obtained new bases for the evaluation of CO-Ne interaction energies. ? We checked the bases on the evaluation of the rovibrational spectrum. ? The results were satisfactory, being the new bases more efficient than those previously available. - Abstract: Recently we have derived new efficient basis sets for the evaluation of interaction energies in the X-Y (X, Y = He, Ne, Ar) van der Waals complexes. Here we extend the study to the CO-Ne complex. For this, we start with a systematic basis set study, where the LPol, MLPol and Jensen's aug-pc-2 basis sets are considered as starting point (for the Ne atom LPol bases are developed). As reference we take interaction energy results obtained with Dunning's augmented correlation consistent polarized valence basis sets. In all cases we test extensions with different sets of midbond functions. With the selected bases we evaluate CCSD(T) interaction potentials, and to check the potentials further, we obtain the ro-vibrational spectrum of the complex. The results are compared to the available experimental data.

2011-07-28

18

Substituent-Induced Intermolecular Interaction in Organic Crystals Revealed by Precise Band-Dispersion Measurements  

Science.gov (United States)

We reveal quite small but different intermolecular valence band dispersions of sub-100-meV scale in crystalline films of Zn and Mn phthalocyanine (ZnPc and MnPc) and fluorinated ZnPc (F16ZnPc). The intermolecular transfer integrals are found to be reasonably dependent on the intermolecular distance with the 75±5meV/Å relation. Furthermore, the angle-resolved photoemission spectra show anomalous dispersive behaviors such as phase flips and local-dimerization-derived periodicities, which originate from the site-specific intermolecular interaction induced by substituents.

Yamane, Hiroyuki; Kosugi, Nobuhiro

2013-08-01

19

Application of charge density methods to a protein model compound: calculation of Coulombic intermolecular interaction energies from the experimental charge density.  

Science.gov (United States)

A combined experimental and theoretical charge density study of the pentapeptide Boc-Gln-d-Iva-Hyp-Ala-Phol (Boc, butoxycarbonyl; Gln, glutamine; Iva, isovaline; Hyp, hydroxyproline; Ala, ethylalanine; Phol, phenylalaninol) is described. The experimental analysis, based on synchrotron x-ray data collected at 20 K, is combined with ab initio theoretical calculations. The topologies of the experimental and theoretical densities are analyzed in terms of the atoms in molecules quantum theory. Topological parameters, including atomic charges and higher moments integrated over the atomic basins, have been evaluated with the program topxd and are used to calculate the electrostatic interactions between the molecules in the crystal. The interaction energies obtained after adding dispersive and repulsive van der Waals contributions agree quite well with those based on M-B3LYP/6-31G** dimer calculations for two of the three dimers in the crystal, whereas for the third a larger stabilization is obtained than predicted by the calculation. The agreement with theory is significantly better than that obtained with multipole moments derived directly from the aspherical atom refinement. The convergence of the interaction as a function of addition of successively higher moments up to and including hexadecapoles (l = 4) is found to be within 2-3 kJ/mol. Although shortcomings of both the theoretical and experimental procedures are pointed out, the agreement obtained supports the potential of the experimental method for the evaluation of interactions in larger biologically relevant molecules. PMID:12221293

Li, Xue; Wu, Guang; Abramov, Yuriy A; Volkov, Anatoliy V; Coppens, Philip

2002-09-17

20

Application of charge density methods to a protein model compound: Calculation of Coulombic intermolecular interaction energies from the experimental charge density  

Science.gov (United States)

A combined experimental and theoretical charge density study of the pentapeptide Boc-Gln-d-Iva-Hyp-Ala-Phol (Boc, butoxycarbonyl; Gln, glutamine; Iva, isovaline; Hyp, hydroxyproline; Ala, ethylalanine; Phol, phenylalaninol) is described. The experimental analysis, based on synchrotron x-ray data collected at 20 K, is combined with ab initio theoretical calculations. The topologies of the experimental and theoretical densities are analyzed in terms of the atoms in molecules quantum theory. Topological parameters, including atomic charges and higher moments integrated over the atomic basins, have been evaluated with the program topxd and are used to calculate the electrostatic interactions between the molecules in the crystal. The interaction energies obtained after adding dispersive and repulsive van der Waals contributions agree quite well with those based on M-B3LYP/6–31G** dimer calculations for two of the three dimers in the crystal, whereas for the third a larger stabilization is obtained than predicted by the calculation. The agreement with theory is significantly better than that obtained with multipole moments derived directly from the aspherical atom refinement. The convergence of the interaction as a function of addition of successively higher moments up to and including hexadecapoles (l = 4) is found to be within 2–3 kJ/mol. Although shortcomings of both the theoretical and experimental procedures are pointed out, the agreement obtained supports the potential of the experimental method for the evaluation of interactions in larger biologically relevant molecules.

Li, Xue; Wu, Guang; Abramov, Yuriy A.; Volkov, Anatoliy V.; Coppens, Philip

2002-01-01

 
 
 
 
21

Intermolecular interactions in poly(vinylidene fluoride) and ?-caprolactam mixtures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Mixtures of poly(vinylidene fluoride) (PVDF) and caprolactam (CPL) have been investigated as models for possible cross-interactions between vinylidene fluoride and amide structural units, that might account for the very fine phase morphology previously observed in PVDF/polyamide 6 blends. Over the entire composition range, the PVDF/CPL mixtures are monophase above the PVDF melting temperature. From the depression of the PVDF melting point, a negative interaction energy density, B, has been ca...

Liu, Zehui; Mare?chal, Philippe; Je?ro?me, Robert

1996-01-01

22

Double strand interaction is the predominant pathway for intermolecular recombination of adeno-associated viral genomes  

International Nuclear Information System (INIS)

Intermolecular recombination is the foundation for dual vector mediated larger gene transfer by recombinant adeno-associated virus (rAAV). To identify precursors for intermolecular recombination, we sequentially infected skeletal muscle with AAV LacZ trans-splicing viruses. At 1 month postinfection, nearly all inputting single-strand (ss) AAV genomes were cleared out in muscle. If ss-ss interaction is absolutely required for intermolecular recombination, LacZ expression from sequential infection will be negligible to that from coinfection. Interestingly, expression from sequential infection reached ?50% of that from coinfection at the 1-month time-point in BL6 mice. In immune deficient SCID mice, expression from sequential infection was comparable to that from coinfection at the 4- and 13-month time points. Our results suggest that ds interaction represents the predominant pathway for AAV intermolecular recombination

2003-08-15

23

The fluorobenzene-argon S(1) excited-state intermolecular potential energy surface.  

Science.gov (United States)

We evaluate the first excited-state (S1) intermolecular potential energy surface for the fluorobenzene-Ar van der Waals complex using the coupled cluster method and the augmented correlation-consistent polarized valence double-zeta basis set extended with a set of 3s3p2d1f1g midbond functions. To calculate the S(1) interaction energies, we use ground-state interaction energies evaluated with the same basis set and the coupled cluster singles and doubles (CCSD) including connected triple excitations [CCSD(T)] model and interaction and excitation energies evaluated at the CCSD level. The surface minima are characterized by the Ar atom located above and below the fluorobenzene ring at a distance of 3.5060 A with respect to the fluorobenzene center of mass and at an angle of 5.89 degrees with respect to the axis perpendicular to the fluorobenzene plane. The corresponding interaction energy is -425.226 cm(-1). The surface is used in the evaluation of the intermolecular level structure of the complex, and the results are compared to the experimental data available and to those found in previous theoretical papers on ground-state potentials for similar complexes. PMID:17658771

Fajín, José Luis Cagide; Capelo, Silvia Bouzón; Fernandez, Berta; Felker, Peter M

2007-08-16

24

Comment on 'Intermolecular interaction potentials of the methane dimer from the local density approximation'  

International Nuclear Information System (INIS)

To verify the recently calculated intermolecular interaction potentials of the methane dimer within the density functional theory using the (Perdew) local density approximation (LDA) [Chen et al., Phys. Rev. A 69, 034701 (2004)], we have performed a parallel series of calculations using the LDA/6-311++G (3df, 3pd) level of theory with selected exchange functionals (B, G96, MPW, O, PBE, PW91, S, and XA). None of the above calculated intermolecular interaction potentials from the local density approximation reproduce the results reported in the commented paper. In addition, we point out the inappropriateness of using the Lennard-Jones function to model the long-range parts of the calculated intermolecular interaction potentials, as suggested positively by Chen et al

2006-01-01

25

Intermolecular interactions between natural polysaccharides and silk fibroin protein.  

Science.gov (United States)

Fabricating novel functional and structural materials from natural renewable and degradable materials has attracted much attention. Natural polysaccharides and proteins are the right natural candidates due to their unique structures and properties. The polysaccharide-protein composites or blends were widely investigated, however, there are few systematical studies on the interactions between natural polysaccharides and silk fibroin protein at the molecular level. Among various interactions, hydrogen bonding, electrostatic interactions and covalent bonding play important roles in the structure and properties of the corresponding materials. Therefore, the focus is placed on the three interactions types in this review. A future challenge is to create polysaccharide and protein composites or blends with tailored structure and properties for the wide applications. PMID:23499097

Shang, Songmin; Zhu, Lei; Fan, Jintu

2013-04-01

26

Liquid chloroform structure from computer simulation with a full ab initio intermolecular interaction potential.  

Science.gov (United States)

We have calculated the intermolecular interaction energies of the chloroform dimer in 12 orientations using the second-order Møller-Plesset perturbation theory. Single point energies of important geometries were calibrated by the coupled cluster with single and double and perturbative triple excitation method. Dunning's correlation consistent basis sets up to aug-cc-pVQZ have been employed in extrapolating the interaction energies to the complete basis set limit values. With the ab initio potential data we constructed a 5-site force field model for molecular dynamics simulations. We compared the simulation results with recent experiments and obtained quantitative agreements for the detailed atomwise radial distribution functions. Our results were also consistent with previous results using empirical force fields with polarization effects. Moreover, the calculated diffusion coefficients reproduced the experimental data over a wide range of thermodynamic conditions. To the best of our knowledge, this is the first ab initio force field which is capable of competing with existing empirical force fields for liquid chloroform. PMID:24320333

Yin, Chih-Chien; Li, Arvin Huang-Te; Chao, Sheng D

2013-11-21

27

Intermolecular interaction potentials of the methane dimer from the local density approximation  

International Nuclear Information System (INIS)

The intermolecular interaction potentials of methane (CH4) dimer are calculated within the density functional theory in the local density approximation (LDA). It is found that the calculated potentials have minima when the intermolecular distance of CH4 dimer is about 7.0 a.u., which is in good agreement with the experiment. The depth of the potential is 0.017 eV. The results obtained by our LDA calculations seem to agree well with those obtained by MP2, MP3, and CCSD from the Moeller-Plesset and coupled cluster methods by Tsuzuki et al. and with the experimental data

2004-03-01

28

Intermolecular interactions between cucurbit[7]uril and pilocarpine.  

Science.gov (United States)

The interactions between cucurbit[7]uril (CB7) macrocycles and pilocarpine (PIL) were investigated in aqueous solution by using (1)H NMR and circular dichroism (CD) spectroscopic techniques. The characterizations of the freeze-drying solid complex were conducted by electrospray ionization mass spectroscopy (ESI-MS), Fourier transform-infrared spectroscopy (FT-IR), thermogravimetry, and differential scanning calorimetry (DSC) techniques. The DSC and thermogravimetry confirmed the production of a thermally stable solid complex. The NMR, CD and ESI-MS measurements confirmed asymmetric induction during the complexation reaction, in which the ?-lactone ring of PIL (not the imidazole nucleus) has been fully encapsulated within the cavity of CB7. The stability of the drug has significantly enhanced as evidenced by the high-performance liquid chromatographic (HPLC) method. The results are discussed in the context of utilizing non-conventional supramolecular host-guest approaches to enhance the chemical stability in aqueous media of hydrophilic PIL drugs as model compounds. The non-classical stereospecific interactions between CB7 and PIL drugs are also highlighted. PMID:24239578

Saleh, Na'il; Al-Handawi, Marieh B; Al-Kaabi, Leena; Ali, Liaquat; Salman Ashraf, S; Thiemann, Thies; Al-Hindawi, Bassam; Meetani, Mohammed

2014-01-01

29

Atom depth analysis delineates mechanisms of protein intermolecular interactions  

International Nuclear Information System (INIS)

Highlights: •3D atom depth analysis is proposed to identify different layers in protein structures. •Amino acid contents for each layers have been analyzed for a large protein dataset. •Charged amino acids in the most external layer are present at very different extents. •Atom depth indexes of K residues reflect their side chains flexibility. •Mobile surface charges can be responsible for long range protein–protein recognition. -- Abstract: The systematic analysis of amino acid distribution, performed inside a large set of resolved protein structures, sheds light on possible mechanisms driving non random protein–protein approaches. Protein Data Bank entries have been selected using as filters a series of restrictions ensuring that the shape of protein surface is not modified by interactions with large or small ligands. 3D atom depth has been evaluated for all the atoms of the 2,410 selected structures. The amino acid relative population in each of the structural layers formed by grouping atoms on the basis of their calculated depths, has been evaluated. We have identified seven structural layers, the inner ones reproducing the core of proteins and the outer one incorporating their most protruding moieties. Quantitative analysis of amino acid contents of structural layers identified, as expected, different behaviors. Atoms of Q, R, K, N, D residues are increasingly more abundant in going from core to surfaces. An opposite trend is observed for V, I, L, A, C, and G. An intermediate behavior is exhibited by P, S, T, M, W, H, F and Y. The outer structural layer hosts predominantly E and K residues whose charged moieties, protruding from outer regions of the protein surface, reorient free from steric hindrances, determining specific electrodynamics maps. This feature may represent a protein signature for long distance effects, driving the formation of encounter complexes and the eventual short distance approaches that are required for protein–protein functional interactions

2013-07-12

30

Theoretical calculations: can Gibbs free energy for intermolecular complexes be predicted efficiently and accurately?  

Science.gov (United States)

The theoretical study has been performed to refine the procedure for calculations of Gibbs free energy with a relative accuracy of less than 1 kcal/mol. Three benchmark intermolecular complexes are examined via several quantum-chemical methods, including the second-order Moller-Plesset perturbation (MP2), coupled cluster (CCSD(T)), and density functional (BLYP, B3LYP) theories augmented by Dunnings correlation-consistent basis sets. The effects of electron correlation, basis set size, and anharmonicity are systematically analyzed, and the results are compared with available experimental data. The results of the calculations suggest that experimental accuracy can be reached only by extrapolation of MP2 and CCSD(T) total energies to the complete basis set. The contribution of anharmonicity to the zero point energy and TDeltaSint values is fairly small. The new, economic way to reach chemical accuracy in the calculations of the thermodynamic parameters of intermolecular interactions is proposed. In addition, interaction energy (De) and free energy change (DeltaA) for considered species have been evaluated by Carr-Parrinello molecular dynamics (CPMD) simulations and static BLYP-plane wave calculations. The free energy change along the reaction paths were determined by the thermodynamic integration/"Blue Moon Ensemble" technique. Comparison between obtained values, and available experimental and conventional ab initio results has been made. We found that the accuracy of CPMD simulations is affected by several factors, including statistical uncertainty and convergence of constrained forces (TD integration), and the nature of DFT (density functional theory) functional. The results show that CPMD technique is capable of reproducing interaction and free energy with an accuracy of 1 kcal/mol and 2-3 kcal/mol respectively. PMID:17340602

Isayev, Olexandr; Gorb, Leonid; Leszczynski, Jerzy

2007-07-15

31

Intermolecular interactions in a radiation field via the method of induced moments  

International Nuclear Information System (INIS)

Molecular quantum electrodynamics is employed to calculate a generalized formula for the energy shift between a pair of molecules that have electric polarizability of arbitrary multipole order and are in the presence of an intense electromagnetic field. In contrast to a previous calculation of the dipole-dipole contribution, which required fourth-order time-dependent perturbation theory for its evaluation, the present approach involves calculating the interaction between the multipole moments induced at each center by the incident beam and the resonant multipole-multipole coupling tensor together with the average value of the spatial correlation function of the displacement field for an N-photon state. The theory developed applies to the situation where the molecular pair is held fixed relative to the direction of propagation of the radiation field or is allowed to be completely randomly oriented. Explicit results are obtained for dipole-quadrupole and quadrupole-quadrupole polarizable molecules. For oriented systems the energy shift for linear and circular polarizations is examined for incident radiation propagating in directions parallel and perpendicular to the intermolecular join, and the asymptotic behavior is obtained at the limits of short and large separation distance. After performing a pair orientation average, the energy shift in the near zone is found to exhibit an R-1 power-law behavior with separation distance, while the far zone has a modulated R-2 dependence in all of the cases considered. None of the energy shifts obtained display discriminatory characteristics, with respect to either the handedness of the incident beam or the individual species

2006-01-01

32

Calculation of intermolecular interaction strengths in the P beta' phase in lipid bilayers. Implications for theoretical models.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The existence of the P beta' phase in certain lipid bilayers is evidence that molecular interactions between lipids are capable of producing unusual large-scale structures at or near biological conditions. The problem of identifying the specific intermolecular interactions responsible for the structures requires construction of theoretical models capable of clear predictions of the observable consequences of postulated intermolecular interactions. To this end we have carried out a twofold mod...

Scott, H. L.; Pearce, P. A.

1989-01-01

33

The Experimental Charge-Density Approach in the Evaluation of Intermolecular Interactions. Application of a New Module of the XD Programming Package to Several Solids Including a Pentapeptide  

Energy Technology Data Exchange (ETDEWEB)

A new module interfaced to the XD programming package has been used in the evaluation of intermolecular interactions and lattice energies of the crystals of p-nitroaniline, l-asparagine monohydrate and the pentapeptide Boc-Gln- d-Iva-Hyp-Ala-Phol (Boc = butoxycarbonyl, Iva = isovaline = ethylalanine, Phol = phenylalaninol).

Abramov, Yu A.; Volkov, Anatoliy; Wu, G; Coppens, P

2000-11-01

34

Theoretical studies of intermolecular interactions: He-water, dioxygen dimer, and rare-gas coronene  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present work recently developed by us in connection with the Consolider-Ingenio ASTROMOL project. First, we report quantum-mechanical calculations of cross sections and rate coefficients for the He + water system, using an accurate ab initio intermolecular potential [J. Chem. Phys. 116, 1397 (2002)]. The state-to-state cross sections do not follow an energy-gap rule but they are rather governed by propensities to certain variations of the asymmetric top quantum numbers. The results are tes...

Herna?ndez, Marta I.; Carmona-novillo, Estela; Bartolomei, Massimiliano; Campos-marti?nez, Jose?; Herna?ndez Lamoneda, Ramo?n; Pirani, Fernando

2012-01-01

35

Intermolecular interactions between imidazole derivatives intercalated in layered solids. Substituent group effect  

Science.gov (United States)

This study sheds light on the intermolecular interactions between imidazole derive molecules (2-methyl-imidazole, 2-ethyl-imidazole and benzimidazole) intercalated in T[Ni(CN)4] layers to form a solid of formula unit T(ImD)2[Ni(CN)4]. These hybrid inorganic-organic solids were prepared by soft chemical routes and their crystal structures solved and refined from X-ray powder diffraction data. The involved imidazole derivative molecules were found coordinated through the pyridinic N atom to the axial positions for the metal T in the T[Ni(CN)4] layer. In the interlayers region ligand molecules from neighboring layers remain stacked in a face-to-face configuration through dipole-dipole and quadrupole-quadrupole interactions. These intermolecular interactions show a pronounced dependence on the substituent group and are responsible for an ImD-pillaring concatenation of adjacent layers. This is supported by the structural information and the recorded magnetic data in the 2-300 K temperature range. The samples containing Co and Ni are characterized by presence of spin-orbit coupling and pronounced temperature dependence for the effective magnetic moment except for 2-ethyl-imidazole related to the local distortion for the metal coordination environment. For this last one ligand a weak ferromagnetic ordering ascribed to a super-exchange interaction between T metals from neighboring layers through the ligands ?-? interaction was detected.

González, M.; Lemus-Santana, A. A.; Rodríguez-Hernández, J.; Aguirre-Velez, C. I.; Knobel, M.; Reguera, E.

2013-08-01

36

A Model DMMP/TiO2 (110) Intermolecular Potential Energy Function Developed from ab Initio Calculations  

International Nuclear Information System (INIS)

A hierarchy of electronic structure calculations, scalings, and fittings were used to develop an analytic intermolecular potential for dimethyl methylphosphonate (DMMP) interacting with the TiO2 rutile (110) surface. The MP2/aug-cc-pVDZ (6-311+G** for Ti) level of theory, with basis set superposition error (BSSE) corrections, was used to calculate multiple intermolecular potential curves between TiO5H6 as a model for the Ti and O atoms of the TiO2 surface, and CH3OH and O=P(CH3)(OH)2 as models for different types of atoms comprising DMMP. Each intermolecular potential energy emphasized a particular atom-atom interaction, and the curves were fit simultaneously by a sum of two-body potentials between the atoms of the two interacting molecules. The resulting analytic intermolecular potential gives DMMP/TiO5H6 potential curves in excellent agreement with those calculated using MP2/aug-cc-pVDZ (6-311+G** for Ti) theory. MP2 theory with the smaller basis set, 6-31++G** (6-31G** for Ti), gives DMMP/TiO5H6 potential energy curves similar to those found using MP2/aug-cc-pVDZ (6-311+G** for Ti), suggesting the smaller basis set may be used to describe DMMP interactions with larger cluster models of the TiO2 surface. The TiO5H6 cluster does not model either the 6-fold coordinated Ti-atoms or the bridging O-atoms of the TiO2 (110) surface and to also model these atoms MP2/6-31++G** (6-31G** for Ti) theory was used to calculate potential energy curves for DMMP interacting with the larger Ti3O13H14 cluster and much large cluster Ti11O40H36 cluster. The two-body potential energy curves for DMMP/TiO5H6 were scaled to fit both the DMMP/Ti3O13H14 and DMMP/Ti11O40H36 potential energy curves. The resulting parameters for the 5- and 6-fold coordinated Ti-atoms and bridging and bulk O-atoms were used to develop an analytic intermolecular potential for DMMP interacting with rutile TiO2 (110).

2011-06-30

37

Vibrational predissociation of Van der Waals molecules and intermolecular potential energy surfaces  

International Nuclear Information System (INIS)

Spectroscopic experiments yield information about energy transfer processes in van der Waals molecules, for which we do not have reliable guides for geometries. Important properties of the molecules are included in the areas of intermolecular potential energy curves, structure, and energy transfer processes. Vibrational predissociation is more fully explored through experimental studies, a theoretical model, numerical results, momentum gap, and relaxation channels

1980-08-29

38

Structure and intermolecular interactions of glipizide from laboratory X-ray powder diffraction.  

Science.gov (United States)

The crystal structure of glipizide, used as a major treatment of type-2 diabetes, has been determined ab initio using variable-temperature laboratory X-ray powder diffraction combined with a direct-space Monte Carlo/simulated annealing methodology. The strengths of the intermolecular interactions (van der Waals, pi-pi stacking, hydrogen bonding and steric interlock) were quantitatively estimated using the thermal expansion data, which were collected in the same set of experiments as those used to determine the structure. PMID:16306678

Burley, Jonathan C

2005-12-01

39

The Molecular Oxygen Tetramer: Intermolecular Interactions and Implications for the $\\epsilon$ Solid Phase  

CERN Multimedia

Recent data have determined that the structure of the high pressure $\\epsilon$ phase of solid oxygen consists of clusters composed of four O$_2$ molecules. This finding has opened the question about the nature of the intermolecular interactions within the molecular oxygen tetramer. We use multiconfigurational ab initio calculations to obtain an adequate characterization of the ground singlet state of (O$_2$)$_4$ which is compatible with the non magnetic character of the $\\epsilon$ phase. In contrast to previous suggestions implying chemical bonding, we show that (O$_2$)$_4$ is a van der Waals like cluster where exchange interactions preferentially stabilize the singlet state. However, as the cluster shrinks, there is an extra stabilization due to many-body interactions that yields a significant softening of the repulsive wall. We show that this short range behavior is a key issue for the understanding of the structure of $\\epsilon$-oxygen.

Bartolomei, Massimiliano; Hernández, Marta I; Pérez-Ríos, Jesús; Campos-Martínez, José; Hernández-Lamoneda, Ramón

2011-01-01

40

The electronic structure and the ferromagnetic intermolecular interactions in the crystal of TEMPO radicals  

Energy Technology Data Exchange (ETDEWEB)

Based on the generalized gradient approximation, full potential linearized augmented plane wave (FP-LAPW) calculations have been performed to study the electronic band structure and the intermolecular ferromagnetic (FM) interactions for the two TEMPO radicals 4-Benzylideneamino-2,2,6,6-tetramethylpiperidin-1-oxyl (1) and 4-(2-naphtylmethyleneamino)-2,2,6,6-tetramethylpiperidin-1-oxyl (2). The total and the partial density of states and the atomic spin magnetic moments are calculated and discussed. The calculation revealed that the two TEMPO radicals have the intermolecular FM interactions, and the spontaneous magnetic moment is 1.0 {mu} {sub B} per molecule of each crystal, which is in good agreement with the experimental value. It is found that the unpaired electrons in these compounds are localized in a molecular orbital constituted primarily of {pi}* (NO) orbital, and the main contribution of the spin magnetic moment comes from the NO-free radical. The origin of FM is also studied in detail.

Zhu, L. [Department of Physics and State Key Laboratory of Laser Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)]. E-mail: wl-zl41@163.com; Yao, K.L. [Department of Physics and State Key Laboratory of Laser Technology, Huazhong University of Science and Technology, Wuhan 430074 (China) and International Center of Materials Physics, Chinese Academy of Science, Shengyang 110015 (China)]. E-mail: klyao@hust.edu.cn; Liu, Z.L. [Department of Physics and State Key Laboratory of Laser Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

2006-06-15

 
 
 
 
41

The benzene-argon ground-state intermolecular potential energy surface revisited.  

Science.gov (United States)

The benzene-Ar ground-state S(0) intermolecular potential energy surface is evaluated using the coupled cluster singles and doubles model including connected triple corrections and the augmented correlation consistent polarized valence triple-zeta basis set extended with a set of 3s3p2d1f1g midbond functions. The surface is characterized by absolute minima of -390.1 cm(-1) where the argon atom is located on the benzene C(6) axis at distances of +/-3.536 A, and has a general shape close to the available ground-state S(0) and the first singlet S(1) and triplet T(1) excited-state surfaces. Using the potential, the intermolecular level structure of the complex is evaluated. The new intermolecular potential energy surface gives very accurate results and improves those previously available. PMID:19354204

Capelo, Silvia Bouzón; Fernández, Berta; Koch, Henrik; Felker, Peter M

2009-04-30

42

Relativistic effects in the intermolecular interaction-induced nuclear magnetic resonance parameters of xenon dimer  

DEFF Research Database (Denmark)

Relativistic effects on the 129Xe nuclear magnetic resonance shielding and 131Xe nuclear quadrupole coupling (NQC) tensors are examined in the weakly bound Xe2 system at different levels of theory including the relativistic four-component Dirac-Hartree-Fock (DHF) method. The intermolecular interaction-induced binary chemical shift d, the anisotropy of the shielding tensor ?s, and the NQC constant along the internuclear axis ?ll are calculated as a function of the internuclear distance. DHF shielding calculations are carried out using gauge-including atomic orbitals. For comparison, the full leading-order one-electron Breit-Pauli perturbation theory (BPPT) is applied using a common gauge origin. Electron correlation effects are studied at the nonrelativistic (NR) coupled-cluster singles and doubles with perturbational triples [CCSD(T)] level of theory. The fully relativistic second-order Møller-Plesset many-body perturbation (DMP2) theory is used to examine the cross coupling between correlation and relativityon NQC. The same is investigated for d and ?s by BPPT with a density functional theory model. A semiquantitative agreement between the BPPT and DHF binary property curves is obtained for d and ?s in Xe2. For these properties, the currently most complete theoretical description is obtained by a piecewise approximation where the uncorrelated relativistic DHF results obtained close to the basis-set limit are corrected, on the one hand, for NR correlation effects and, on the other hand, for the BPPT-based cross coupling of relativity and correlation. For ?ll, the fully relativistic DMP2 results obtain a correction for NR correlation effects beyond MP2. The computed temperature dependence of the second virial coefficient of the 129Xe nuclear shielding is compared to experiment in Xe gas. Our best results, obtained with the piecewise approximation for the binary chemical shift combined with the previously published state of the art theoretical potential energy curve for Xe2, are in excellent agreement with the experiment for the first time. © 2007 American Institute of Physics. [DOI: 10.1063/1.2777143

Hanni, Matti; Lantto, Perttu

2007-01-01

43

INS study of intermolecular interaction at the silicone-fumed silica interface  

International Nuclear Information System (INIS)

Complete text of publication follows. The paper presents results related to the interface formed between finned silica particles and polydimethylsiloxane polymers, presented in the study by a five-member cyclic oligomer SiS. The substrate surface is terminated by either hydroxyl units or by trimethylsiloxy ones. When the interface is formed, methyl units are the main constituents providing neutron scattering. Protium/deuterium exchange has been used to distinguish the latter belonging to either adsorbate or substrate. A detailed analysis of the intermolecular interaction impact on both adsorbed molecule and substrate has been performed. The observed features are supported by the vibrational spectra calculations performed on the basis of a modem quantum-chemical approach and supplemented by the solution of the inverse spectral problem. (author)

1999-01-01

44

Manifestation of structure and intermolecular interactions of biologically active brassinosteroids in infrared spectra  

Science.gov (United States)

We have analyzed the IR spectra obtained for steroidal phytohormones 24-epibrassinolide, 24-epicastasterone, 28-homobrassinolide, and 28-homocastasterone. The characteristic frequencies of the stretching vibrations of the hydrocarbon groups CH3, CH2, and CH and also the C=O groups in the spectra of brassinolides are higher than in the spectra of castasterones, which makes it possible to identify them from the IR spectra. Study of the spectra of these brassinosteroids in different media (pressed samples in KBr, films, solutions in CHCl3 and CDCl3) allowed us to establish the presence of intermolecular interactions in which C=O and OH groups, OH-OH groups participate, and also the possible formation of intramolecular hydrogen bonds between the OH groups of the molecules.

Borisevich, N. A.; Skornyakov, I. V.; Khripach, V. A.; Tolstorozhev, G. B.; Zhabinskii, V. N.

2007-09-01

45

Intermolecular interaction between a branching ribozyme and associated homing endonuclease mRNA.  

Science.gov (United States)

RNA tertiary interactions involving docking of GNRA (N; any base; R; purine) hairpin loops into helical stem structures on other regions of the same RNA are one of the most common RNA tertiary interactions. In this study, we investigated a tertiary association between a GAAA hairpin tetraloop in a small branching ribozyme (DiGIR1) and a receptor motif (HEG P1 motif) present in a hairpin structure on a separate mRNA molecule. DiGIR1 generates a 2', 5' lariat cap at the 5' end of its downstream homing endonuclease mRNA by catalysing a self-cleavage branching reaction at an internal processing site. Upon release, the 5' end of the mRNA forms a distinct hairpin structure termed HEG P1. Our biochemical data, in concert with molecular 3D modelling, provide experimental support for an intermolecular tetraloop receptor interaction between the L9 GAAA in DiGIR1 and a GNRA tetraloop receptor-like motif (UCUAAG-CAAGA) found within the HEG P1. The biological role of this interaction appears to be linked to the homing endonuclease expression by promoting post-cleavage release of the lariat capped mRNA. These findings add to our understanding of how protein-coding genes embedded in nuclear ribosomal DNA are expressed in eukaryotes and controlled by ribozymes. PMID:21495911

Birgisdottir, Ása B; Nielsen, Henrik; Beckert, Bertrand; Masquida, Benoît; Johansen, Steinar D

2011-04-01

46

Intermolecular interaction between a branching ribozyme and associated homing endonuclease mRNA  

DEFF Research Database (Denmark)

Abstract RNA tertiary interactions involving docking of GNRA (N; any base; R; purine) hairpin loops into helical stem structures on other regions of the same RNA are one of the most common RNA tertiary interactions. In this study, we investigated a tertiary association between a GAAA hairpin tetraloop in a small branching ribozyme (DiGIR1) and a receptor motif (HEG P1 motif) present in a hairpin structure on a separate mRNA molecule. DiGIR1 generates a 2', 5' lariat cap at the 5' end of its downstream homing endonuclease mRNA by catalysing a self-cleavage branching reaction at an internal processing site. Upon release, the 5' end of the mRNA forms a distinct hairpin structure termed HEG P1. Our biochemical data, in concert with molecular 3D modelling, provide experimental support for an intermolecular tetraloop receptor interaction between the L9 GAAA in DiGIR1 and a GNRA tetraloop receptor-like motif (UCUAAG-CAAGA) found within the HEG P1. The biological role of this interaction appears to be linked to the homing endonuclease expression by promoting post-cleavage release of the lariat capped mRNA. These findings add to our understanding of how protein-coding genes embedded in nuclear ribosomal DNA are expressed in eukaryotes and controlled by ribozymes.

Birgisdottir, Asa B; Nielsen, Henrik

2011-01-01

47

Modeling intermolecular interactions of physisorbed organic molecules using pair potential calculations  

Energy Technology Data Exchange (ETDEWEB)

The understanding and control of epitaxial growth of organic thin films is of crucial importance in order to optimize the performance of future electronic devices. In particular, the start of the submonolayer growth plays an important role since it often determines the structure of the first layer and subsequently of the entire molecular film. We have investigated the structure formation of 3,4,9,10-perylene-tetracarboxylic dianhydride and copper-phthalocyanine molecules on Au(111) using pair-potential calculations based on van der Waals and electrostatic intermolecular interactions. The results are compared with the fundamental lateral structures known from experiment and an excellent agreement was found for these weakly interacting systems. Furthermore, the calculations are even suitable for chemisorptive adsorption as demonstrated for copper-phthalocyanine/Cu(111), if the influence of charge transfer between substrate and molecules is known and the corresponding charge redistribution in the molecules can be estimated. The calculations are of general applicability for molecular adsorbate systems which are dominated by electrostatic and van der Waals interaction.

Kroeger, Ingo; Stadtmueller, Benjamin; Wagner, Christian; Weiss, Christian; Temirov, Ruslan; Tautz, F. Stefan; Kumpf, Christian [Peter Gruenberg Institut (PGI-3), Forschungszentrum Juelich, 52425 Juelich (Germany); Juelich-Aachen Research Alliance (JARA) - Fundamentals of Future Information Technology, 52425 Juelich (Germany)

2011-12-21

48

Intermolecular interactions in binary mixtures of 2-Chloroethanol with 2-Dimethylaminoethanol and 2-Diethylaminoethanol at different temperatures  

Science.gov (United States)

The ultrasonic velocity (u) and density (?) of binary mixtures of 2-Chloroethanol (2-CletOH) with 2-Dimethylaminoethanol (DMAE) and 2-Diethylaminoethanol (DEAE) have been measured over the entire concentration range at temperatures 293.15, 303.15 and 313.15 K. The ultrasonic velocity and density data are used to estimate adiabatic compressibility (?S), intermolecular free length (Lf), molar sound velocity (R), molar compressibility (B) and specific acoustic impedance (Z) along with excess values of ultrasonic velocity (uE), adiabatic compressibility (?SE), intermolecular free length (LfE), acoustic impedance (ZE) and molar volume (VmE). The infrared spectra of both of the systems, 2-CletOH + DMAE and 2-CletOH + DEAE, have also been recorded at room temperature (298.15 K). The observed variations of these parameters, with concentration and temperature, are discussed in terms of the intermolecular interactions between the unlike molecules of the binary mixtures.

Pandey, Puneet Kumar; Awasthi, Anjali; Awasthi, Aashees

2013-09-01

49

Intermolecular versus intramolecular interactions of the vinculin binding site 33 of talin  

Energy Technology Data Exchange (ETDEWEB)

The cytoskeletal proteins talin and vinculin are localized at cell-matrix junctions and are key regulators of cell signaling, adhesion, and migration. Talin couples integrins via its FERM domain to F-actin and is an important regulator of integrin activation and clustering. The 220 kDa talin rod domain comprises several four- and five-helix bundles that harbor amphipathic {alpha}-helical vinculin binding sites (VBSs). In its inactive state, the hydrophobic VBS residues involved in binding to vinculin are buried within these helix bundles, and the mechanical force emanating from bound integrin receptors is thought necessary for their release and binding to vinculin. The crystal structure of a four-helix bundle of talin that harbors one of these VBSs, coined VBS33, was recently determined. Here we report the crystal structure of VBS33 in complex with vinculin at 2 {angstrom} resolution. Notably, comparison of the apo and vinculin bound structures shows that intermolecular interactions of the VBS33 {alpha}-helix with vinculin are more extensive than the intramolecular interactions of the VBS33 within the talin four-helix bundle.

Yogesha, S.D.; SHarff, A.; Bricogne, G.; Izard, .T. (Globel Phasing); (Scripps)

2012-03-13

50

Vibrational dynamics, intermolecular interactions, and compound formation in GeH4-H2 under pressure  

Science.gov (United States)

Optical microscopy, spectroscopic and x-ray diffraction studies at high-pressure are used to investigate intermolecular interactions in binary mixtures of germane (GeH4)+hydrogen (H2). The measurements reveal the formation of a new molecular compound, with the approximate stoichiometry GeH4(H2)2, when the constituents are compressed above 7.5 GPa. Raman and infrared spectroscopic measurements show multiple H2 vibrons substantially softened from bulk solid hydrogen. With increasing pressure, the frequencies of several Raman and infrared H2 vibrons decrease, indicating anomalous attractive interaction for closed-shell, nonpolar molecules. Synchrotron powder x-ray diffraction measurements show that the compound has a structure based on face-centered cubic (fcc) with GeH4 molecules occupying fcc sites and H2 molecules likely distributed between Oh and Td sites. Above ca. 17 GPa, GeH4 molecules in the compound become unstable with respect to decomposition products (Ge+H2), however, the compound can be preserved metastably to ca. 27 GPa for time-scales of the order of several hours.

Strobel, Timothy A.; Chen, Xiao-Jia; Somayazulu, Maddury; Hemley, Russell J.

2010-10-01

51

Theoretical study of intermolecular interactions in meso-tetraphenylporphyrin diacid dimer (H4TPPCl2)2.  

Science.gov (United States)

The intermolecular interactions between two meso-tetraphenylporphyrin diacid H(4)TPPCl(2) monomers are investigated by density functional theory with the PBE1PBE functional and 6-31G* basis set. Structures of five stable isomers of (H(4)TPPCl(2))(2) are determined. It is found that the interaction (IMHB-1) of Cl with ortho H atoms in two phenyl groups of H(4)TPPCl(2) is unique in that it is the strongest interaction between two H(4)TPPCl(2) monomers. Natural bond orbital analysis is carried out to explain the subtle differences of hydrogen bondings in these isomers. To understand the interactions of water molecule with H(4)TPPCl(2) and (H(4)TPPCl(2))(2), structures of H(4)TPPCl(2) x H(2)O and nine isomers of (H(4)TPPCl(2))(2) x H(2)O are also determined. The binding energy of H(4)TPPCl(2) x H(2)O is 36.47 kJ mol(-1), less than that of the most stable structure of (H(4)TPPCl(2))(2) dimers, 41.59 kJ mol(-1). The dimers containing the special IMHB-1 interactions may be the elementary building blocks for the aggregation of H(4)TPPCl(2), which is supported by the crystal structure of H(4)TPPCl(2).H(2)O x 2CH(3)CN. Thus, study of the interactions between two or a small number of gas molecules can provide important information for understanding the main interactions and stable structures in related condensed-phase systems. PMID:19325989

Ma, Yan-Ping; He, Sheng-Gui; Ding, Xun-Lei; Wang, Zhe-Chen; Xue, Wei; Shi, Qiang

2009-04-14

52

Key Inter-molecular Interactions in the E. Coli 70S Ribosome Revealed by Coarse-Grained Analysis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The ribosome is a very large complex, which consists of many RNA and protein molecules and plays a central role in protein biosynthesis in all organisms. Extensive interactions between different molecules are critical to ribosomal functional dynamics. In this work, inter-molecular interactions in the E. coli 70S ribosome are investigated by coarse-grained (CG) analysis. CG models are defined to preserve dynamic domains in RNAs and proteins, and capture functional motions in the ribosome, then...

Zhang, Zhiyong; Sanbonmatsu, Karissa Y.; Voth, Gregory A.

2011-01-01

53

Theoretical study of intermolecular magnetic interaction of chromium(V)-nitrido complex self-assembly with tetradentate Schiff base ligand  

Science.gov (United States)

A theoretical study of the intermolecular magnetic interaction of [CrN(salpn)] is discussed based on DFT calculations. The close contact between the 2p orbitals on the axial nitrogen and other 3d orbitals besides the 3d xy orbital on the adjacent chromium is effective for ferromagnetic coupling. The magnetic interaction is rationally explained by the significantly large spin polarization of the axial nitrogen.

Matsuoka, Naoki; Yoshioka, Naoki

2012-01-01

54

Intermolecular interactions and solvent diffusion in ordered nanostructures formed by self-assembly of block copolymers  

Science.gov (United States)

Hydrogels formed by Poloxamer poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) block copolymers find various pharmaceutical and biomedical applications. A variety of ordered structures can be exhibited by Poloxamer block copolymers in selective solvents such as water, for example, micellar cubic phase, hexagonal phase, lamellar phase, etc. We are interested in the thermodynamic and transport properties of water in such hydrogels that have an ordered (lyotropic liquid crystalline) structure. We have investigated the time evolution of water loss from Poloxamer gel films under a driving force of known water vapor pressure in the air in contact with the film. The experimental data on the drying process have been fitted to the diffusion equation for water in the film, under a boundary condition that includes the water concentration in the gel at infinite time; the water diffusion coefficient and other parameters have thus been obtained. The water chemical potential and osmotic pressure in the gel have been obtained from osmotic stress measurements. The osmotic pressure (force), together with data on the corresponding lyotropic liquid crystal spacing (distance) that we obtained from Small Angle X-Ray Scattering (SAXS) measurements, have been analyzed to provide information on the prevailing intermolecular (inter-assembly) forces in the gel. The forces in the gel reveal interactions that occur at two levels, that of the PEO coil and that of the PEO segment.

Gu, Zhiyong

55

A combined experimental and quantum chemical studies on molecular structure, spectral properties, intra and intermolecular interactions and first hyperpolarizability of 4-(benzyloxy)benzaldehyde thiosemicarbazone and its dimer  

Science.gov (United States)

In the present work, a detailed spectroscopic analysis of 4-(benzyloxy)benzaldehyde thiosemicarbazone (3) has been carried out using 1H NMR, 13C NMR, UV-Visible and FT-IR spectroscopic techniques. The quantum chemical calculations have been carried out using DFT level of theory, B3LYP functional and 6-31G(d,p) basis set. The calculated thermodynamic parameters show that the formation of 3 is an exothermic and spontaneous reaction at 25 °C. The vibrational analysis indicates the formation of dimer in the solid state by intermolecular hydrogen bonding (Nsbnd H⋯Sdbnd C) and the binding energy of dimer is calculated to be 11.2 kcal/mol, using DFT calculation. NBO analysis is carried out to investigate the charge transfer in various intra and intermolecular interactions involved in dimer. Topological parameters at bond critical points (BCPs) are calculated to analyze the strength and nature of various intra and intermolecular interactions in dimer by Bader's 'Atoms in molecules' AIM theory in detail. The local reactivity descriptors such as Fukui functions (fk+, fk-), local softnesses (sk+, sk-) and electrophilicity indices (?k+, ?k-) analysis are performed to determine the reactive sites within molecule. Non linear optical (NLO) behavior of title compound is investigated by the computed value of first hyperpolarizability (?0).

Kumar, Amit; Rawat, Poonam; Baboo, Vikas; Verma, Divya; Singh, R. N.; Saxena, Deepti; Gauniyal, H. M.; Pandey, Anoop Kumar; Pal, Harish

2013-02-01

56

Intermolecular Interactions in Ternary Glycerolâ??Sampleâ??H2O : Towards Understanding the Hofmeister Series (V)  

DEFF Research Database (Denmark)

We studied the intermolecular interactions in ternary glycerol (Gly)â??sample (S)â??H2O systems at 25â??°C. By measuring the excess partial molar enthalpy of Gly, HGlyEHEGly, we evaluated the Glyâ??Gly enthalpic interaction, HGly-GlyEHEGly--Gly, in the presence of various samples (S). For S, tert-butanol (TBA), 1-propanol (1P), urea (UR), NaF, NaCl, NaBr, NaI, and NaSCN were used. It was found that hydrophobes (TBA and 1P) reduce the values of HGly-GlyEHEGly--Gly considerably, but a hydrophile (UR) had very little effect on HGly-GlyEHEGly--Gly. The results with Na salts indicated that there have very little effect on HGly-GlyEHEGly--Gly. This contrasts with our earlier studies on 1Pâ??Sâ??H2O in that Na+, Fâ?? and Clâ?? are found as hydration centers from the induced changes on HIP-IPEHEIP--IP in the presence of S, while Brâ??, Iâ??, and SCNâ?? are found to act as hydrophiles. In comparison with the Hofmeister ranking of these ions, the kosmotropes are hydration centers and the more kosmotropic the higher the hydration number, consistent with the original Hofmeisterâ??s concept of â??H2O withdrawing power.â? Brâ??, Iâ?? and SCNâ??, on the other hand, acted as hydrophiles and the more chaotropic they are the more hydrophilic. These observations hint that whatever effect each individual ion has on H2O, it is sensitive only to hydrophobes (such as 1P) but not to hydrophiles (such as Gly). This may have an important bearing towards understanding the Hofmeister series, since biopolymers are amphiphilic and their surfaces are covered by hydrophobic as well as hydrophilic parts.

Westh, Peter; Rasmussen, Erik Lumby

2011-01-01

57

Structural elucidation and contribution of intermolecular interactions in O-hydroxy acyl aromatics: Insights from X-ray and Hirshfeld surface analysis  

Science.gov (United States)

An O-hydroxy acyl aromatics, namely 1,1?,1?-(2,4,6-trihydroxybenzene-1,3,5-triyl) triethanone (1) was synthesized and characterized by spectroscopic and single crystal X-ray structural studies with a detailed scrutiny of visualizing and exploring intermolecular interactions in molecular crystals through Hirshfeld surface. The crystal packing of (1) exhibits intermolecular ?–? stacking interactions to generate a one-dimensional parallel stacked ribbon propagating along (0 0 1) direction. Hirshfeld surface analysis for visually analyzing intermolecular interactions in crystal structures employing molecular surface contours and 2D fingerprint plots have been used to scrutinize molecular shapes. Crystal structure analysis supported with the Hirshfeld surface and fingerprint plots enabled the identification of the significant intermolecular interactions.

Seth, Saikat Kumar

2014-05-01

58

The effect of the intermolecular potential formulation on the state-selected energy exchange rate coefficients in N2-N2 collisions.  

Science.gov (United States)

The rate coefficients for N2-N2 collision-induced vibrational energy exchange (important for the enhancement of several modern innovative technologies) have been computed over a wide range of temperature. Potential energy surfaces based on different formulations of the intramolecular and intermolecular components of the interaction have been used to compute quasiclassically and semiclassically some vibrational to vibrational energy transfer rate coefficients. Related outcomes have been rationalized in terms of state-to-state probabilities and cross sections for quasi-resonant transitions and deexcitations from the first excited vibrational level (for which experimental information are available). On this ground, it has been possible to spot critical differences on the vibrational energy exchange mechanisms supported by the different surfaces (mainly by their intermolecular components) in the low collision energy regime, though still effective for temperatures as high as 10,000 K. It was found, in particular, that the most recently proposed intermolecular potential becomes the most effective in promoting vibrational energy exchange near threshold temperatures and has a behavior opposite to the previously proposed one when varying the coupling of vibration with the other degrees of freedom. PMID:24590423

Kurnosov, Alexander; Cacciatore, Mario; Laganà, Antonio; Pirani, Fernando; Bartolomei, Massimiliano; Garcia, Ernesto

2014-04-01

59

Studies in intermolecular energy transfer between certain aromatic bases and 2, 3-Dichloronaphthoquinone  

International Nuclear Information System (INIS)

Spectrophotometric studies of intermolecular energy transfer leading to charge transfer complexation between certain aromatic amines, such as N, N-dimethylamine, N-methylamine, p-toluidine, and diphenylamine and 2,3-dichloronaphthoquinone, have been carried out in chloroform medium. All the complexes show charge-transfer bands in the visible region, and they form 1:1 complexes of n-II type. The relevant spectral parameters for the charge-transfer complexes such as association constant, Gibb's free energy, and molar extinction coefficient are presented. A comparative study on the evaluation of association constant and molar extinction is investigated by modified B-H, Scott, and F-H-W equations. (author)

2002-01-01

60

Cooperativity of anion⋯? and ?⋯? interactions regulates the self-assembly of a series of carbene proligands: Towards quantitative analysis of intermolecular interactions with Hirshfeld surface  

Science.gov (United States)

The cooperative effect of weak non-covalent forces between anions and electron deficient aromatics by ?⋯? stacking of a series of carbene proligands (1-3) have been thoroughly explored by crystallographic studies. Structural analysis revealed that the anion⋯? and ?⋯? interactions along with intermolecular hydrogen bonding mutually cooperate to facilitate the assembling of the supramolecular framework. The ?⋯? and corresponding anion⋯? interactions have been investigated in the title carbene proligands despite their association with counter ions. The presence of the anion in the vicinity of the ?-system leads to the formation of anion⋯?/?⋯?/?⋯anion network for an inductive stabilization of the assemblies. To assess the dimensionality of the supramolecular framework consolidated by cooperative anion⋯?/?⋯? interactions and hydrogen bonding, different substituent effects in the carbene backbone have been considered to tune these interactions. These facts show that the supramolecular framework based on these cooperative weak forces may be robust enough for application in molecular recognition. The investigation of close intermolecular interactions between the molecules via Hirshfeld surface analyses is presented in order to reveal subtle differences and similarities in the crystal structures. The decomposition of the fingerprint plot area provides a percentage of each intermolecular interaction, allowing for a quantified analysis of close contacts within each crystal.

Samanta, Tapastaru; Dey, Lingaraj; Dinda, Joydev; Chattopadhyay, Shyamal Kumar; Seth, Saikat Kumar

2014-06-01

 
 
 
 
61

Lack of evidence for intermolecular epistatic interactions between adiponectin and resistin gene polymorphisms in Malaysian male subjects  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Epistasis (gene-gene interaction) is a ubiquitous component of the genetic architecture of complex traits such as susceptibility to common human diseases. Given the strong negative correlation between circulating adiponectin and resistin levels, the potential intermolecular epistatic interactions be [...] tween ADIPOQ (SNP+45T > G, SNP+276G > T, SNP+639T > C and SNP+1212A > G) and RETN (SNP-420C > G and SNP+299G > A) gene polymorphisms in the genetic risk underlying type 2 diabetes (T2DM) and metabolic syndrome (MS) were assessed. The potential mutual influence of the ADIPOQ and RETN genes on their adipokine levels was also examined. The rare homozygous genotype (risk alleles) of SNP-420C > G at the RETN locus tended to be co-inherited together with the common homozygous genotypes (protective alleles) of SNP+639T > C and SNP+1212A > G at the ADIPOQ locus. Despite the close structural relationship between the ADIPOQ and RETN genes, there was no evidence of an intermolecular epistatic interaction between these genes. There was also no reciprocal effect of the ADIPOQ and RETN genes on their adipokine levels, i.e., ADIPOQ did not affect resistin levels nor did RETN affect adiponectin levels. The possible influence of the ADIPOQ gene on RETN expression warrants further investigation.

Cia-Hin, Lau; Sekaran, Muniandy.

62

Intermolecular interactions in mixtures of poly (ethylene glycol) with methoxybenzene and ethoxybenzene: Volumetric and viscometric studies  

International Nuclear Information System (INIS)

Highlights: • Density and viscosity values of PEG400 + methoxybenzene or + ethoxybenzene were measured. • The excess molar volume and thermodynamic functions of activation were calculated. • The results were interpreted in light of polymer–solvent interactions. • The changes in activation function indicate the viscous flow process. • The thermodynamic functions were correlated with the suitable equations. -- Abstract: The density and viscosity values of the binary mixtures of {poly (ethylene glycol) (PEG400) + methoxybenzene, or + ethoxybenzene} have been measured at T = (298.15, 308.15, and 318.15) K. From these experimental values, the excess molar volume, apparent specific volume, partial specific volume of solute, partial specific volume of solvent and excess Gibbs free energy of activation have been computed over the entire range of composition at three temperatures. From the experimental data, the thermodynamic functions of activation have been estimated for each binary mixture. The obtained results have been interpreted in light of polymer–solvent interactions and packing effects. The signs of excess molar volume and deviations of excess Gibbs free energy of activation have been used to obtain some information in regard to existence of specific interactions between PEG400 and solvents molecules. The changes in entropy and enthalpy of activation from the initial state to the transition state were also calculated in order to see which one of these functions controls viscous flow process in the studied polymer solutions. The excess molar volume and excess Gibbs free energy of activation values have been adequately fitted to the Redlich–Kister polynomial. Apparent specific volume values were correlated with the suitable equation. The different models proposed for correlating the viscosity of polymer solutions or liquid mixtures (segment-based-Eyring–NRTL, segment-based-Eyring–Wilson, Grunbreg–Nissan, Frenkel, Hind et al., Katti–Chauddhri, Tamura–Kurata, Auslander and McAllister) have also been used to fit the viscosity values

2014-04-01

63

Theoretical Studies on the Intermolecular Interactions of Potentially Primordial Base-Pair Analogues  

Energy Technology Data Exchange (ETDEWEB)

Recent experimental studies on the Watson Crick type base pairing of triazine and aminopyrimidine derivatives suggest that acid/base properties of the constituent bases might be related to the duplex stabilities measured in solution. Herein we use high-level quantum chemical calculations and molecular dynamics simulations to evaluate the base pairing and stacking interactions of seven selected base pairs, which are common in that they are stabilized by two NH O hydrogen bonds separated by one NH N hydrogen bond. We show that neither the base pairing nor the base stacking interaction energies correlate with the reported pKa data of the bases and the melting points of the duplexes. This suggests that the experimentally observed correlation between the melting point data of the duplexes and the pKa values of the constituent bases is not rooted in the intrinsic base pairing and stacking properties. The physical chemistry origin of the observed experimental correlation thus remains unexplained and requires further investigations. In addition, since our calculations are carried out with extrapolation to the complete basis set of atomic orbitals and with inclusion of higher electron correlation effects, they provide reference data for stacking and base pairing energies of non-natural bases.

Leszczynski, Jerzy [Computational Center for Molecular Structure and Interactions, Jackson, MS; Sponer, Judit [Academy of Sciences of the Czech Republic; Sponer, Jiri [Academy of Sciences of the Czech Republic; Sumpter, Bobby G [ORNL; Fuentes-Cabrera, Miguel A [ORNL; Vazquez-Mayagoitia, Alvaro [ORNL

2010-01-01

64

Intermolecular Interactions Between Proteins and Individual Poly(ethylene oxide) Chains Measured via High-Resolution Force Spectroscopy  

Science.gov (United States)

The noncovalent adsorption of biofluid proteins onto biomaterial surface coatings, such as poly(ethylene oxide) (PEO), is known to be a primary determining factor of biocompatibility. The molecular mechanisms and precise details of the nanoscale forces acting between proteins and synthetic surface polymers are complex and poorly understood. We have directly measured the intermolecular interaction forces in aqueous buffer solution between individual end-grafted PEO chains and a probe tip covalently bound with human serum albumin (HSA) using high-resolution force spectroscopy. Long-range adhesion is frequently observed between the HSA probe tip and the PEO chain on retraction, which is strong enough to allow stretching of the individual PEO chains (Fadhesion=0.125nN±0.22nN, Dadhesion=246nm±148nm). Statistical analysis, comparison to a variety of control experiments, and theoretical modeling enable us to interpret these experimental results in terms of electrostatic, hydrogen, and steric interactions.

Ortiz, Christine; Rixman, Monica

2002-03-01

65

A method based on the DAOSD approach to estimate the variation of the peak position and bandwidth caused by intermolecular interactions  

Science.gov (United States)

Subtle spectral variations caused by intermolecular interactions, which are hardly observed in the original one-dimensional spectra or the second derivative spectra, can be distinctly visualized via spectral patterns in two-dimensional spectra generated by using double asynchronous orthogonal sample designed scheme (DAOSD). If intermolecular interaction only brings about band-shift on a characteristic peak, a pair of cross peaks appears in the corresponding near diagonal region. If intermolecular interaction induces variation of bandwidth only, a cluster of cross peaks forms a diamond pattern in the near diagonal region. In both cases, the variation of peak position or bandwidth can be deduced quantitatively from the pattern of cross peaks. If intermolecular interaction causes variations on both peak position and bandwidth, four cross peaks form a butterfly pattern. In this case, however, it is not straightforward to estimate the variation of peak position and bandwidth directly from the patterns of the cross peaks. In this paper, we propose an algorithm to estimate the variations of peak position and bandwidth of a characteristic peak caused by intermolecular interactions. The validity of this approach was confirmed by computer simulation on several model systems.

Bi, Quan; Chen, Jing; Li, Xiaopei; Shi, Jia-Jia; Guo, Ran; Zhai, Yanjun; Xu, Yizhuang; Noda, Isao; Wu, Jinguang

2014-07-01

66

Relação entre transferência de carga e as interações intermoleculares em complexos de hidrogênio heterocíclicos Relationship between charge transfer and intermolecular interactions in heterocyclic hydrogen-bonded complexes  

Directory of Open Access Journals (Sweden)

Full Text Available Hydrogen-bonded complexes formed by the interaction of the heterocyclic molecules C2H4O and C2H5N with HF, HCN, HNC and C2H2 have been studied using density functional theory. The hydrogen bond strength has been analyzed through electron density charge transfer from the proton acceptor to the proton donor. The density charge transfer has been estimated using different methods such as Mulliken population analysis, CHELPG, GAPT and AIM. It has been shown that AIM-estimated charge transfer correlates very well with the hydrogen bond energy and the infrared bathochromic effect of the proton donor stretching frequencies.

Boaz G. Oliveira

2007-08-01

67

Intermolecular C–H⋯O interactions in cyclopentanone: An inelastic neutron scattering study  

Science.gov (United States)

The inelastic neutron scattering (INS) spectra of cyclopentanone were obtained for pure and 50% CCl4 solution forms. Spectra are compared with infrared and Raman data, and with DFT calculated eigenvectors. This exercise aims to find spectroscopic evidence in the neutron spectra for the presence of C–H⋯O hydrogen bonds. These are weak interactions with an energy of ca. ?6 kJ mol?1 as predicted by DFT. The neutron spectra show narrow and sharp bands which allows for an assignment of the vibrational modes. The simulated neutron spectrum of C–H⋯O bonded cyclopentanone dimers matches the experimental spectrum of the pure compound, whereas the monomer simulation monomer matches the experimental spectrum of the diluted solution, meaning that such interaction can be probed by INS. Assignment of the 95 cm?1 band to the ?H⋯O anti-translational mode, being supported by DFT results and in agreement with previous literature data, is considered and discussed.

Vaz, Pedro D.; Nolasco, Mariela M.; Ribeiro-Claro, Paulo J. A.

2013-12-01

68

The experimental charge-density approach in the evaluation of intermolecular interactions. Application of a new module of the XD programming package to several solids including a pentapeptide.  

Science.gov (United States)

A new module interfaced to the XD programming package has been used in the evaluation of intermolecular interactions and lattice energies of the crystals of p-nitroaniline, L-asparagine monohydrate and the pentapeptide Boc-Gln-D-Iva-Hyp-Ala-Phol (Boc = butoxycarbonyl, Iva = isovaline = ethylalanine, Phol = phenylalaninol). The electrostatic interactions are evaluated with the atom-centered distributed multipoles from KRMM (kappa'-restricted multipole model) refinements, using the Buckingham expression for non-overlapping charge densities. Results for p-nitroaniline are compared with Hartree-Fock (HF), density functional (DFT) and Moller-Plesset (MP2) supermolecular calculations and with HF and DFT periodic calculations. The HF and DFT methods fail to predict the stability of the p-nitroaniline crystal but the results of the experimental charge-density approach (ECDA) are in good agreement with both MP2 interaction energies and the experimental lattice energy. ECDA results for L-asparagine monohydrate compare well with those from DFT supermolecular and periodic HF calculations. The disorder of the terminal group in the pentapeptide, which persists at the experimental temperature of 20 K, corresponds to an energy difference of only 0.35 kJ mol(-1), which is too small to be reproduced with current methods. PMID:11058845

Abramov, Y A; Volkov, A; Wu, G; Coppens, P

2000-11-01

69

Modest protein-crowder attractive interactions can counteract enhancement of protein association by intermolecular excluded volume interactions.  

Science.gov (United States)

We study the effects of attractive interactions between spherical crowders and protein residues on the thermodynamics and structure of two weakly binding protein complexes: ubiquitin/UIM1 and cytochrome c/cytochrome c peroxidase. Systematic replica exchange Monte Carlo (REMC) simulations are performed over a range of attraction strengths and crowder packing fractions using a transferable coarse-grained protein binding model. We find that moderate attractive interactions (?0.2 kcal/mol) between crowders and protein residues can destabilize protein association, and therefore counteract the stabilizing effect of excluded volume interactions. The destabilization of protein binding, as measured by an increase in binding free energy, increases with increasing crowder packing fraction. For a critical attraction strength value, which is found to be approximately independent of crowder packing fraction, the destabilization due to attractions is exactly canceled by the stabilization effect of excluded volume interactions. This results in a net zero change in binding free energy with respect to a crowder-free solution. Further, we find that attractive interactions between crowders and protein residues can favor transiently bound encounter complexes over the native specific complexes in the bound state. We propose a simple theoretical model based on the scaled particle theory augmented by a mean-field attraction term that can explain our simulation results semiquantitatively. PMID:21361356

Rosen, Jonathan; Kim, Young C; Mittal, Jeetain

2011-03-24

70

Sensitivity analysis of rotational energy transfer processes to the intermolecular potential  

International Nuclear Information System (INIS)

This paper considers the sensitivity of rotational energy transfer processes to the variation of parameters within an assumed model intermolecular potential. The following cross sections are considered here: integral state to state, pressure broadening, effective diffusion and viscosity, and final state summed integral cross sections. In order to simplify the calculation of cross sections, attention is restricted to the scattering of an atom and linear rigid rotor. Furthermore, the collision dynamics are approximated by using the infinite order sudden (IOS) method. It is shown that use of the IOS method allows for the very simple generation of first order sensitivity coefficients (i.e., the partial derivative of cross sections with respect to potential parameters). Particular attention is focused upon the sensitivities of different cross sections and combinations of cross sections to the various parameters. The first order sensitivities are also used to derive new coefficients which describe how the potential parameters correlate given a limited set of cross section measurements. These coefficients are shown to be particularly important in determining the degree to which a set of measurements is able to define various parameters of the assumed potential

1980-02-15

71

Sensitivity analysis of rotational energy transfer processes to the intermolecular potential  

Energy Technology Data Exchange (ETDEWEB)

This paper considers the sensitivity of rotational energy transfer processes to the variation of parameters within an assumed model intermolecular potential. The following cross sections are considered here: integral state to state, pressure broadening, effective diffusion and viscosity, and final state summed integral cross sections. In order to simplify the calculation of cross sections, attention is restricted to the scattering of an atom and linear rigid rotor. Furthermore, the collision dynamics are approximated by using the infinite order sudden (IOS) method. It is shown that use of the IOS method allows for the very simple generation of first order sensitivity coefficients (i.e., the partial derivative of cross sections with respect to potential parameters). Particular attention is focused upon the sensitivities of different cross sections and combinations of cross sections to the various parameters. The first order sensitivities are also used to derive new coefficients which describe how the potential parameters correlate given a limited set of cross section measurements. These coefficients are shown to be particularly important in determining the degree to which a set of measurements is able to define various parameters of the assumed potential.

Eno, L.; Rabitz, H.

1980-02-15

72

Transport properties in mixtures involving carbon dioxide at low and moderate density: test of several intermolecular potential energies and comparison with experiment  

Energy Technology Data Exchange (ETDEWEB)

It is the purpose of this paper to extract unlike intermolecular potential energies of five carbon dioxide-based binary gas mixtures including CO{sub 2}-He, CO{sub 2}-Ne, CO{sub 2}-Ar, CO{sub 2}-Kr, and CO{sub 2}-Xe from viscosity data and compare the calculated potentials with other models potential energy reported in literature. Then, dilute transport properties consisting of viscosity, diffusion coefficient, thermal diffusion factor, and thermal conductivity of aforementioned mixtures are calculated from the calculated potential energies and compared with literature data. Rather accurate correlations for the viscosity coefficient of afore-cited mixtures embracing the temperature range 200 Kintermolecular potentials energy. Our estimated accuracies for the viscosity are to within {+-}2%. In addition, the calculated potential energies are used to present smooth correlations for other transport properties. The accuracies of the binary diffusion coefficients are of the order of {+-}3%. Finally, the unlike interaction energy and the calculated low density viscosity have been employed to calculate high density viscosities using Vesovic-Wakeham method. (orig.)

Moghadasi, Jalil; Yousefi, Fakhri [Shiraz University, Department of Chemistry, Shiraz (Iran); Papari, Mohammad Mehdi; Faghihi, Mohammad Ali [Shiraz University of Technology, Department of Chemistry, Shiraz (Iran); Mohsenipour, Ali Asghar [University of Waterloo, Department of Chemical Engineering, Waterloo (Canada)

2009-09-15

73

Intermolecular interactions and thermodynamic properties of 3,6-diamino-1,2,4,5-tetrazine-1,4-dioxide dimers: A density functional theoretical study  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Three fully optimized structures of 3,6-diamino-1,2,4,5-tetrazine-1,4-dioxide (LAX-112) dimers have been obtained with the density functional theory (DFT) method at the B3LYP/6-311++G level. Vibrational frequency calculations were carried out to ascertain that each structure is a minimum (no imagina [...] ry frequencies). The intermolecular interaction energy is calculated with the basis set superposition error (BSSE) correction and zero point energy (ZPE) correction. The greatest corrected binding energy among the three dimers is -42.38 kJ mol-1. The charge redistribution mainly occurs on the adjacent O(N)......H atoms between submolecules and the charge transfer between two subsystems is very small. Natural bond orbital (NBO) analysis was performed to reveal the origin of the interaction. Based on the vibrational analysis, the standard thermodynamic functions (heat capacities (cºp), entropies (S°m) and enthalpies (H°m)) and the changes of thermodynamic properties from the monomer to dimer with the temperature ranging from 200.00 K to 800.00 K have been obtained using statistical thermodynamics. The results show that the strong hydrogen bonds dominantly contribute to the dimers, while the bonding energies are not only determined by the hydrogen bonding. The dimerization process of dimer II can occur spontaneously at room temperature.

Ning Ning, Zhao; Ya Ling, Zhao; Yin, Hu; Hai Xia, Ma; Feng Qi, Zhao; Ji Rong, Song.

74

Multibody effects in intermolecular interactions and reaction pathways for catalytic processes. Part II the contributions of Sidonio Castillo  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish Aquí continuaremos la revisión del trabajo de Octavio Novaro y sus colaboradores en los importantes campos de la no aditividad de las interacciones intermoleculares y de la catálisis, enfatizando las contribuciones de Sidonio Castillo que resultaron altamente útiles en este esfuerzo conjunto, antes [...] de su prematuro fallecimiento. Sus primeros trabajos, con reconocidos científico polacos en los trímeros de metáno y amoniaco y con coautores ingleses en trimeros y tetrameros de fósforo y nitrógeno, serán presentados primero, seguidos de sus estudiós sobre la activación catalítica de moléculas de metáno, silano y germano (de alto potencial en aplicaciónes valiosas). Sus primeros trabajos en catálisis formaron parte de su tesis doctoral dirigida por O. Novaro y los últimos fueron consecuencia de las tesis doctorales que el Dr. Castillo dirigió a los otros dos coautores de esta revisión. Esta labor fue desgraciadamente interrumpida por la muerte de Sidonio. Así concluyó su corta pero brillante carrera. Abstract in english We here continue the review on the work of Octavio Novaro and collaborators in the important field of nonadditivity of intermolecular interactions and catalysis, with special interest in the work that Sidonio Castillo contributed to this effort before his demise. His early work with Polish coauthors [...] on methane and ammonia trimers and with British coauthors on N3, P3, N4 and P4 are highlighted. Then our focus will shift mainly to his work on the activation of methane, silane and germane starting with his Ph.D. thesis under O. Novaro and ending in his last papers with the present authors which marked the end of his short but brilliant career.

O., Novaro; J.H., Pacheco-Sánchez; H., Luna.

75

Weak Chemical Interaction and van der Waals Forces: A Combined Density Functional and Intermolecular Perturbation Theory - Application to Graphite and Graphitic Systems  

Science.gov (United States)

In this contribution we address the theoretical underst anding of weak chemical interactions and of the van der Waals forces, in conjunction with the last developments in this area and selected applications to nanostructures. In the first section, we highlight the importance of these interactions, in physics and chemistry and also in biology, and we recall early treatments of these issues, as those by van der Waals and London. After a brief review of the existing methods to treat such interactions, we present a model based on DFT (for each van der Waals-interacting independent system) and an intermolecular perturbation theory that uses a localized orbitals basis set. We will first detail a weak overlap expansion (LCAO-S 2) as a perturbation treatment to determine the weak chemical interaction. Then we will show how to implement the van der Waals interaction in the DFT solution, from the dipolar approximation in a perturbation theory. We apply this model to a reference system for weak interactions, i.e., the interaction between two planes of graphene. In the framework of a minimal basis set that describes each independent system and the weak chemical repulsion, we show that it is necessary to take into account atomic dipole transitions involving high excited states like 3d orbitals to properly describe the van der Waals interaction. We demonstrate how the delicate balance between chemical repulsion and van der Waals attractive interaction gives the equilibrium geometry and the binding energy of the system. Moreover, as an extension of this work, we obtain the adsorption energy of a carbon nanotube on graphene, the adsorption energy of a C60 molecule on a carbon nanotube, and the energy of a C60 molecule encapsulated in a carbon nanotube. This gives us the opportunity to discuss incommensurable systems. A complete study of C60 dimers is also presented with future perspective for the study of C60 molecular crystals. We will conclude with an overview of this work, discussing interaction and transport at metal-organics interfaces from the point of view of applications in the field of molecular electronics.

Dappe, Y. J.; Ortega, J.; Flores, F.

76

Weak carbonyl-methyl intermolecular interactions in acetone clusters explored by IR plus VUV spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer The carbonyl overtone of acetone clusters is observed by IR-VUV spectroscopy. Black-Right-Pointing-Pointer Acetone molecules in the dimer are stacked with an antiparallel way. Black-Right-Pointing-Pointer The structure of the acetone trimer and the tetramer are the cyclic structures. Black-Right-Pointing-Pointer The carbonyl groups would interact with the methyl groups in acetone clusters. Black-Right-Pointing-Pointer These weak interactions are further confirmed by H/D substitution experiment. -- Abstract: Size-selected IR-VUV spectroscopy is employed to detect vibrational characteristics in the region 2850 {approx} 3550 cm{sup -1} of neutral acetone and its clusters (CH{sub 3}COCH{sub 3}){sub n} (n = 1-4). Features around 3440 cm{sup -1} in the spectra of acetone monomer and its clusters are assigned to the carbonyl stretch (CO) overtone. These features red-shift from 3455 to 3433 cm{sup -1} as the size of the clusters increases from the monomer to the tetramer. Based on calculations, the experimental IR spectra in the C=O overtone region suggest that the dominant structures for the acetone trimer and tetramer should be cyclic in the supersonic expansion sample. This study also suggests that the carbonyl groups interact with the methyl groups in the acetone clusters. These weak interactions are further confirmed by the use of deuterium substitution.

Guan, Jiwen [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); Hu, Yongjun, E-mail: yjhu@scnu.edu.cn [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); Xie, Min [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); Bernstein, Elliot R. [Department of Chemistry, Colorado State University, Fort Collins, CO 80523-1872 (United States)

2012-09-11

77

Weak carbonyl-methyl intermolecular interactions in acetone clusters explored by IR plus VUV spectroscopy  

International Nuclear Information System (INIS)

Highlights: ? The carbonyl overtone of acetone clusters is observed by IR-VUV spectroscopy. ? Acetone molecules in the dimer are stacked with an antiparallel way. ? The structure of the acetone trimer and the tetramer are the cyclic structures. ? The carbonyl groups would interact with the methyl groups in acetone clusters. ? These weak interactions are further confirmed by H/D substitution experiment. -- Abstract: Size-selected IR–VUV spectroscopy is employed to detect vibrational characteristics in the region 2850 ? 3550 cm?1 of neutral acetone and its clusters (CH3COCH3)n (n = 1–4). Features around 3440 cm?1 in the spectra of acetone monomer and its clusters are assigned to the carbonyl stretch (CO) overtone. These features red-shift from 3455 to 3433 cm?1 as the size of the clusters increases from the monomer to the tetramer. Based on calculations, the experimental IR spectra in the C=O overtone region suggest that the dominant structures for the acetone trimer and tetramer should be cyclic in the supersonic expansion sample. This study also suggests that the carbonyl groups interact with the methyl groups in the acetone clusters. These weak interactions are further confirmed by the use of deuterium substitution.

2012-09-11

78

Modeling Intermolecular Interactions in Nanotubes, Fullerenes and Graphite using a New Long-Range Potential  

Science.gov (United States)

The cohesive energy and compressibility of strands of a single-wall nanotube rope has been computed using a new long-range potential energy function derived from accurate ab initio quantum chemistry calculations of the benzene dimer and calibrated for energetic and mechanical properties of graphite (at pressures up to 12 GPa). We also use this potential to calculate a variety of properties of carbon nanotubes (both single- and multi-wall) and fullerenes. Extensive comparisons are made with previously published potentials.

Jaffe, Richard; Halicioglu, Timur; Han, Jie; Yang, Liu; Huo, Winifred (Technical Monitor)

1998-01-01

79

Computational investigation of intermolecular interactions in polymer mixtures: Polycarbonate and poly(methyl methacrylate)  

Energy Technology Data Exchange (ETDEWEB)

Molecular modeling and semiempirical quantum mechanical calculations on model compounds can give us detailed information about specific interactions in polymer mixtures. This study examines interactions between a poly(methyl methacrylate) (PMMA) tetramer and the polycarbonate (PC) repeat unit. The results suggested that PC-PMMA mixtures are stabilizing by hydrogen bonds between a carbonyl oxygen on one polymer and a proton or protons on the other. Multiple hydrogen bonds occur; stabilized generally increases with the number of hydrogen bonds. Several configurations had a PMMA carbonyl O H-bonded to a PC ring H, and the adjacent PC carbyonyl O H-bonded to PMMA methyl and methylene H`s. This suggests that the reduced PC mobility observed in PC-PMMA mixtures arises from suppression of both ring flips and carbonate group motion.

Fitzwater, S. [Rohm and Haas Co., Spring House, PA (United States)

1993-12-31

80

Prediction of polymer mixture compatibility by Monte Carlo simulation of intermolecular binary interactions  

CERN Document Server

We have evaluated conformational and orientational averages of binary interaction integrals for pairs of chains constituting atomistic representations of short polymer molecules. By considering A-A, B-B and A-B pairs, we relate these results with the Flory-Huggins parameter for the A-B mixtures. This parameter is commonly accepted as a good indicator of compatibility. Since the method ignores the simultaneous interactions with other molecules in the mixture, the local environment is approximately described by introducing an effective medium dielectric constant whose value is conveniently parameterized. The results for four different real systems are compared with data obtained from experimental neutron scattering data. The method qualitatively predicts the sign and variation with temperature in the four different cases, also showing a reasonable quantitative agreement in some of the cases. Its performance is discussed in comparison with a standard method that evaluates the Flory-Huggins parameter by calculati...

Ahmadi, Amirhossein

2009-01-01

 
 
 
 
81

Determination of stepsize parameters for intermolecular vibrational energy transfer: Progress report, May 1, 1987-April 30, 1988  

International Nuclear Information System (INIS)

Intermolecular vibrational energy transfer for highly excited polyatomic molecules is involved in any mechanism in which excitation energy is required (pyrolysis) or in which energy must be removed from a hot source (cooling). The average energy removed per collision, , is a useful quantity to compare efficiency for energy transfer. The objectives of this work are: to determine the dependence of on excitation energy and on the molecular complexity (number of vibrational modes) of substrate and deactivator; to assess the importance of intermolecular attractions (complex formation) on vibrational energy transfer; to obtain detailed information on the energy distribution after collision and to evaluate the importance of on high-temperature unimolecular reactions. This information will be obtained by monitoring the time dependence of the infrared emission, ultraviolet absorption, refractive index and pressure. The results from these complementary techniques will be benchmarked with values from previous studies on the relaxation of chemically activated alkyl and fluoroalkyl radicals. Trajectory calculations simulating energy transfer are being performed for ''generic'' substrate/deactivator pairs to provide additional details and insight on the important parameters. Model calculations are also being performed to determine the feasibility of obtaining information from experimental data for high-temperature unimolecular reactions

1988-01-01

82

Dilution Effects in a Spin Crossover System, Modelled in Terms of Direct and Indirect Intermolecular Interactions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have studied by 57Fe Mössbauer spectroscopy and magnetic measurements the spin transition exhibited by the series: , consisting of a spin-crossover iron(II) system diluted in a high-spin cobalt(II) matrix. We performed Monte Carlo simulations of the thermal variation of the high-spin fraction, using a two-level Ising-type Hamiltonian. A good agreement with experiment is obtained by the introduction of an indirect interaction of the spin-crossover units via the non-spin crossover unit, the...

Constant-machado, H.; Linares, J.; Varret, F.; Haasnoot, J.; Martin, J.; Zarembowitch, J.; Dworkin, A.; Bousseksou, A.

1996-01-01

83

Lateral intermolecular interaction in Langmuir-Blodgett films of octa-alkyl hydrogen phthalocyanines  

Energy Technology Data Exchange (ETDEWEB)

Piezomodulated absorption spectra of Langmuir-Blodgett films of (C[sub 8]H[sub 17])[sub 8]H[sub 2]Pc and (C[sub 12]H[sub 25])[sub 8]H[sub 2]Pc were measured at 100K. The separations of four absorption bands (1.60,1.64,1.76 and 2.05eV) are increased by a uniaxial compressive stress applied along the film plane. These spectral features are explained by assuming lateral interactions among the [pi] electrons of the H[sub 2]Pc rings which are parallel to the surface. ((orig.))

Yudasaka, Masako (Faculty of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240 (Japan)); Tanaka, Masatoshi (Faculty of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240 (Japan)); Sakata, Kazumasa (Faculty of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240 (Japan)); Kurita, Susumu (Faculty of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240 (Japan)); Nakahara, Hiroo (Faculty of Science, Saitama University, Urawa, Saitama 338 (Japan)); Fukuda, Kiyoshige (Faculty of Science, Saitama University, Urawa, Saitama 338 (Japan)); Kitahara, Kiyoshi (Faculty of Engineering, Saitama University, Urawa, Saitama 338 (Japan)); Nishi, Hisao (Faculty of Engineering, Saitama University, Urawa, Saitama 338 (Japan))

1994-09-01

84

Redetermined structure of diphenylphosphonimidotriphenylphosphorane: location of the hydrogen atoms and analysis of the intermolecular interactions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The title compound, C30H25NOP2, is a bulky phosphazene derivative. Its previous crystal structure [Cameron et al. (1979). Acta Cryst. B35, 1373–1377] is confirmed and its H atoms have been located in the present study. The formal P=N double bond is about 0.05?Å shorter than the P—N single bond and the large P=N—P bond angle reflects the steric strain in the molecule. An intramolecular C—H...O interaction occurs. In the crystal, short C—H...O contacts c...

Richard Betz; Thomas Gerber; Eric Hosten; Henk Schalekamp

2011-01-01

85

Intramolecular and Intermolecular Interactions of Protein Kinase B Define Its Activation In Vivo  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Protein kinase B (PKB/Akt) is a pivotal regulator of diverse metabolic, phenotypic, and antiapoptotic cellular controls and has been shown to be a key player in cancer progression. Here, using fluorescent reporters, we shown in cells that, contrary to in vitro analyses, 3-phosphoinositide–dependent protein kinase 1 (PDK1) is complexed to its substrate, PKB. The use of Förster resonance energy transfer detected by both frequency domain and two-photon time domain fluorescence lifetime imagin...

2007-01-01

86

Carbon dioxide clathrate hydrates: selective role of intermolecular interactions and action of the SDS catalyst.  

Science.gov (United States)

The ability of a single sodium dodecyl sulfate (SDS) molecule to promote the formation of CO2 clathrate hydrates in water (as it does for methane) has been investigated at the microscopic level. For this purpose, the components of the related force field were carefully formulated and assembled following the procedure previously adopted for methane. The properties of the whole system (as well as those of its components) were analyzed by carrying out extended molecular dynamics calculations. Contrary to what happens for methane, the calculations singled out the propensity of CO2 (pure) water clusters to form clathrate hydrate-like structures and the disappearance of such propensity when a single SDS molecule is added to the clusters. This feature was found to be due to the strong interaction of carbon dioxide with the additive that makes the SDS molecule lose its shape together with its ability to drive water molecules to form a suitable cage. PMID:23635031

Albertí, M; Pirani, F; Laganà, A

2013-08-15

87

Radiative recombination of trapped excitons in Alq3 films: Importance of intermolecular interactions  

Science.gov (United States)

We investigate the light emission of optically excited tris(8-hydroxyquinolinato) aluminum (Alq3) films by temperature-dependent, time-integrated, as well as time-resolved photoluminescence (PL) at various photon densities. The Alq3 films are deposited on Si (001) substrate using organic molecular beam deposition. At high excitation densities, the PL efficiency decreases when the temperature is reduced from 170 to 15 K. At low laser intensities, the PL efficiency is nearly temperature independent. The observed PL quenching at high-excitation densities is assigned to singlet-singlet annihilation revealing a low-temperature bimolecular quenching coefficient that is more than two orders of magnitude higher than previously reported at room temperature. The observed strong bimolecular interaction at low temperature is attributed to an enhanced local (microscopic) density of captured excitons in extended traps. The reduction of the exciton annihilation with increasing temperature is assigned to a thermally activated occupation of nonquenchable localized exciton states. Above 190 K, the PL efficiency starts to decrease independently from the excitation level which is ascribed to a thermally activated detrapping of excitons and subsequent migration to nonradiative centers outside the traps. A coupled-rate equation model, including bimolecular quenching, thermally activated occupation of nonquenchable states, and detrapping of excitons at higher temperatures, supports these interpretations.

Ajward, A. M.; Wang, X.; Wickremasinghe, N.; DeSilva, L. A. A.; Wagner, H. P.

2013-07-01

88

Fabrication and Intermolecular Interactions of Silk Fibroin/Hydroxybutyl Chitosan Blended Nanofibers  

Directory of Open Access Journals (Sweden)

Full Text Available The native extracellular matrix (ECM is composed of a cross-linked porous network of multifibril collagens and glycosaminoglycans. Nanofibrous scaffolds of silk fibroin (SF and hydroxybutyl chitosan (HBC blends were fabricated using 1,1,1,3,3,3-hexa?uoro-2-propanol (HFIP and trifluoroacetic acid (TFA as solvents to biomimic the native ECM via electrospinning. Scanning electronic microscope (SEM showed that relatively uniform nanofibers could be obtained when 12% SF was blended with 6% HBC at the weight ratio of 50:50. Meanwhile, the average nano?brous diameter increased when the content of HBC in SF/HBC blends was raised from 20% to 100%. Fourier transform infrared spectra (FTIR and 13C nuclear magnetic resonance (NMR showed SF and HBC molecules existed in hydrogen bonding interactions but HBC did not induce conformation of SF transforming from random coil form to ?-sheet structure. X-ray diffraction (XRD confirmed the different structure of SF/HBC blended nanofibers from both SF and HBC. Thermogravimetry-Differential thermogravimetry (TG-DTG results demonstrated that the thermal stability of SF/HBC blend nanofibrous scaffolds was improved. The results indicated that the rearrangement of HBC and SF molecular chain formed a new structure due to stronger hydrogen bonding between SF and HBC. These electrospun SF/HBC blended nanofibers may provide an ideal tissue engineering scaffold and wound dressing.

Xiu-Mei Mo

2011-03-01

89

Exploring contribution of intermolecular interactions in supramolecular layered assembly of naphthyridine co-crystals: Insights from Hirshfeld surface analysis of their crystalline states  

Science.gov (United States)

Co-crystals of 1a and 1b have been prepared by slow evaporation of the solutions of mixtures of 2,7-dimethyl-1,8-naphthyridine (1), urea (a) and thiourea (b). The structures of the complexes are determined by the single crystal X-ray diffraction and a detailed investigation of the crystal packing and classification of intermolecular interactions is presented by means of Hirshfeld surface analysis which is of considerable current interest in crystal engineering. The X-ray study reveals that the co-crystal formers are envisioned to produce N–H⋯N hydrogen bond as well as N–H⋯O/N–H⋯S pair-wise hydrogen bonds and also the weaker aromatic ?⋯? interactions which cooperatively take part in the crystal packing. The recurring feature of the self-assembly in the compounds is the appearance of the molecular ribbon through multiple hydrogen bonding which are further stacked into molecular layers by ?⋯? stacking interactions. Hirshfeld surface analysis for visually analyzing intermolecular interactions in crystal structures employing molecular surface contours and 2D Fingerprint plots have been used to examine molecular shapes. Crystal structure analysis supported with the Hirshfeld surface and fingerprint plots enabled the identification of the significant intermolecular interactions.

Seth, Saikat Kumar; Das, Nirmal Kumar; Aich, Krishnendu; Sen, Debabrata; Fun, Hoong-Kun; Goswami, Shyamaprasad

2013-09-01

90

Clarification of isomeric structures and the effect of intermolecular interactions in blue-emitting aluminum complex Alq3 using first-principles 27Al NMR calculations  

Science.gov (United States)

We have performed structure analysis of the blue-emitting aluminum complex Alq3 using 27Al NMR and gauge-including projector-augmented wave calculations. The results clearly show that 27Al NMR spectra are insensitive to intermolecular interactions, thus providing a means of carrying out precise intramolecular structure determination. The key determinant of the blue-shifted emission of Alq3 is the facial isomerization.

Suzuki, Furitsu; Nishiyama, Yusuke; Kaji, Hironori

2014-06-01

91

A unified model for simulating liquid and gas phase, intermolecular energy transfer: N2 + C6F6 collisions  

Science.gov (United States)

Molecular dynamics simulations were used to study relaxation of a vibrationally excited C6F6* molecule in a N2 bath. Ab initio calculations were performed to develop N2-N2 and N2-C6F6 intermolecular potentials for the simulations. Energy transfer from "hot" C6F6 is studied versus the bath density (pressure) and number of bath molecules. For the large bath limit, there is no heating of the bath. As C6F6* is relaxed, the average energy of C6F6* is determined versus time, i.e., ?E(t)?, and for each bath density ?E(t)? is energy dependent and cannot be fit by a single exponential. In the long-time limit C6F6 is fully equilibrated with the bath. For a large bath and low pressures, the simulations are in the fixed temperature, independent collision regime and the simulation results may be compared with gas phase experiments of collisional energy transfer. The derivative d[?E(t)?]/dt divided by the collision frequency ? of the N2 bath gives the average energy transferred from C6F6* per collision ??Ec?, which is in excellent agreement with experiment. For the ˜100-300 ps simulations reported here, energy transfer from C6F6* is to N2 rotation and translation in accord with the equipartition model, with no energy transfer to N2 vibration. The energy transfer dynamics from C6F6* is not statistically sensitive to fine details of the N2-C6F6 intermolecular potential. Tests, with simulation ensembles of different sizes, show that a relatively modest ensemble of only 24 trajectories gives statistically meaningful results.

Paul, Amit K.; Kohale, Swapnil C.; Pratihar, Subha; Sun, Rui; North, Simon W.; Hase, William L.

2014-05-01

92

Collecting high-order interactions in an effective pairwise intermolecular potential using the hydrated ion concept: The hydration of Cf3+  

Science.gov (United States)

This work proposes a new methodology to build interaction potentials between a highly charged metal cation and water molecules. These potentials, which can be used in classical computer simulations, have been fitted to reproduce quantum mechanical interaction energies (MP2 and BP86) for a wide range of [M(H2O)n]m+(H2O)? clusters (n going from 6 to 10 and ? from 0 to 18). A flexible and polarizable water shell model (Mobile Charge Density of Harmonic Oscillator) has been coupled to the cation-water potential. The simultaneous consideration of poly-hydrated clusters and the polarizability of the interacting particles allows the inclusion of the most important many-body effects in the new polarizable potential. Applications have been centered on the californium, Cf(III) the heaviest actinoid experimentally studied in solution. Two different strategies to select a set of about 2000 structures which are used for the potential building were checked. Monte Carlo simulations of Cf(III)+500 H2O for three of the intermolecular potentials predict an aquaion structure with coordination number close to 8 and average R_{{Cf-O}} in the range 2.43-2.48 Å, whereas the fourth one is closer to 9 with R_{{Cf-O}} = 2.54 Å. Simulated EXAFS spectra derived from the structural Monte Carlo distribution compares fairly well with the available experimental spectrum for the simulations bearing 8 water molecules. An angular distribution similar to that of a square antiprism is found for the octa-coordination.

Galbis, Elsa; Hernández-Cobos, Jorge; Pappalardo, Rafael R.; Marcos, Enrique Sánchez

2014-06-01

93

Collecting high-order interactions in an effective pairwise intermolecular potential using the hydrated ion concept: The hydration of Cf(3+).  

Science.gov (United States)

This work proposes a new methodology to build interaction potentials between a highly charged metal cation and water molecules. These potentials, which can be used in classical computer simulations, have been fitted to reproduce quantum mechanical interaction energies (MP2 and BP86) for a wide range of [M(H2O)n](m+)(H2O)? clusters (n going from 6 to 10 and ? from 0 to 18). A flexible and polarizable water shell model (Mobile Charge Density of Harmonic Oscillator) has been coupled to the cation-water potential. The simultaneous consideration of poly-hydrated clusters and the polarizability of the interacting particles allows the inclusion of the most important many-body effects in the new polarizable potential. Applications have been centered on the californium, Cf(III) the heaviest actinoid experimentally studied in solution. Two different strategies to select a set of about 2000 structures which are used for the potential building were checked. Monte Carlo simulations of Cf(III)+500 H2O for three of the intermolecular potentials predict an aquaion structure with coordination number close to 8 and average [Formula: see text] in the range 2.43-2.48 Å, whereas the fourth one is closer to 9 with [Formula: see text] = 2.54 Å. Simulated EXAFS spectra derived from the structural Monte Carlo distribution compares fairly well with the available experimental spectrum for the simulations bearing 8 water molecules. An angular distribution similar to that of a square antiprism is found for the octa-coordination. PMID:24907987

Galbis, Elsa; Hernández-Cobos, Jorge; Pappalardo, Rafael R; Marcos, Enrique Sánchez

2014-06-01

94

A Theoretical Study of Intermolecular Interaction and Hydrogen Bond for Furan with HCl and CH4-nCln (n = 0-3  

Directory of Open Access Journals (Sweden)

Full Text Available Furan has both the oxygen lone pair electrons and an aromatic ?-electron. The study of the interaction between furan as a proton acceptor and a proton donor is important to understand the properties of furan and the related hydrogen bond. The geometries, intermolecular energies and vibrational properties of the furan-HCl and furan-CH4-nCln (n = 0-3 complexes have been performed using the second order Moller-Plesset perturbation theory. The NBO analysis of the optimized geometries has also been performed. The optimized geometries of furan-HCl and furan-CH4-nCln (n = 0-3 show both the C(Cl-H...O and C(Cl-H...? interactions. In all of the optimized geometries of furan-CH4-nCln (n = 0-3, C-H bond lengths are shorten and vibrational frequencies are blue-shifted, while for the furan-HCl complex, C-H bond length is lengthened and vibrational frequencies are red-shifted. The NBO analysis shows that, for the furan-CH4-nCln (n = 0-3 complexes, the charge transfer from the lone pairs of the O atom to both ?*(CH antibonding MO and lone pairs of Cl atom, which is the important feature for blue-shifted hydrogen bond. Both lone pairs and ? electrons of furan can be acted as a proton acceptor interacting with a proton donor. Cl-H...O(? is a conventional hydrogen bond , while C-H...O(? is a blue-shifted hydrogen bond.

Daiqian Xie

2003-05-01

95

Crystal habits of cubic insulin from porcine pancreas and evaluation of intermolecular interactions by macrobond and EET analyses  

Science.gov (United States)

Experimental and theoretical investigations of the crystal growth of cubic insulin from porcine pancreas were carried out. Three different crystal habits, cube, cube and dodecahedron, and rhombic dodecahedron forms, were obtained. Judging from the results of macroseeding, the most stable of these forms would be the rhombic dodecahedron surrounded by {1 1 0} faces. Molecular interactions in the crystal were evaluated by the macrobond analysis and electrostatic energy of transfer (EET) analysis. The calculated surface energy of {1 1 0} was lower than {1 0 0} by around 40%, which was consistent with the experimental results. Atomic EET supported the macrobond analysis, where the number of hydrogen bonds was primarily evaluated. At the same time, it was suggested that the parameters of the interaction energies of electrically neutral pairs would be smaller than those of charged pairs. The contribution from the bound water molecules to the crystal stabilization was discussed.

Ootaki, Masanori; Endo, Shigeru; Sugawara, Yoko; Takahashi, Takuya

2009-08-01

96

Intramolecular photo-switching and intermolecular energy transfer as primary photoevents in photoreceptive processes: The case of Euglena gracilis  

International Nuclear Information System (INIS)

In this paper we report the results of measurements performed by FLIM on the photoreceptor of Euglenagracilis. This organelle consists of optically bistable proteins, characterized by two thermally stable isomeric forms: A498, non fluorescent and B462, fluorescent. Our data indicate that the primary photoevent of Euglena photoreception upon photon absorption consists of two contemporaneous different phenomena: an intramolecular photo-switch (i.e., A498 becomes B462), and a intermolecular and unidirectional Forster-type energy transfer. During the FRET process, the fluorescent B462 form acts as donor for the non-fluorescent A498 form of the protein nearby, which acts as acceptor. We hypothesize that in nature these phenomena follow each other with a domino progression along the orderly organized and closely packed proteins in the photoreceptor layer(s), modulating the isomeric composition of the photoreceptive protein pool. This mechanism guarantees that few photons are sufficient to produce a signal detectable by the cell.

2009-07-24

97

Comparison of Cluster, Slab, and Analytic Potential Models for the Dimethyl Methylphosphonate (DMMP)/TiO2 (110) Intermolecular Interaction  

Energy Technology Data Exchange (ETDEWEB)

In a previous study (J. Phys. Chem. C 2011, 115, 12403) cluster models for the TiO2 rutile (110) surface and MP2 calculations were used to develop an analytic potential energy function for dimethyl methylphosphonate (DMMP) interacting with this surface. In the work presented here, this analytic potential and MP2 cluster models are compared with DFT "slab" calculations for DMMP interacting with the TiO2 (110) surface and with DFT cluster models for the TiO2 (110) surface. The DFT slab calculations were performed with the PW91 and PBE functionals. The analytic potential gives DMMP/ TiO2 (110) potential energy curves in excellent agreement with those obtained from the slab calculations. The cluster models for the TiO2 (110) surface, used for the MP2 calculations, were extended to DFT calculations with the B3LYP, PW91, and PBE functional. These DFT calculations do not give DMMP/TiO2 (110) interaction energies which agree with those from the DFT slab calculations. Analyses of the wave functions for these cluster models show that they do not accurately represent the HOMO and LUMO for the surface, which should be 2p and 3d orbitals, respectively, and the models also do not give an accurate band gap. The MP2 cluster models do not accurately represent the LUMO and that they give accurate DMMP/TiO2 (110) interaction energies is apparently fortuitous, arising from their highly inaccurate band gaps. Accurate cluster models, consisting of 7, 10, and 15 Ti-atoms and which have the correct HOMO and LUMO properties, are proposed. The work presented here illustrates the care that must be taken in "constructing" cluster models which accurately model surfaces.

Yang, Li; Tunega, Daniel; Xu, Lai; Govind, Niranjan; Sun, Rui; Taylor, Ramona; Lischka, Hans; De Jong, Wibe A.; Hase, William L.

2013-08-29

98

High pressure structural investigations of 2,5-di(4-pyridyl)-1,3,4-oxadiazole-importance of strain studies for the description of intermolecular interactions  

International Nuclear Information System (INIS)

Results of a high pressure x-ray study of 2,5-di(4-pyridyl)-1,3,4-oxadiazole up to 2.5 GPa are presented and discussed. Parameters for the Murnaghan equation of state are derived. The bulk modulus amounts to K0 = 4.6 ± 0.3 GPa and its pressure derivative to K0' = 7.4 ± 0.6. These values are comparable to values of other diphenyl-1,3,4-oxadiazoles. The anisotropy of the compression is analysed using the strain tensor and discussed based on the anisotropy of the intermolecular interactions

2006-06-14

99

High pressure structural investigations of 2,5-di(4-pyridyl)-1,3,4-oxadiazole-importance of strain studies for the description of intermolecular interactions  

Energy Technology Data Exchange (ETDEWEB)

Results of a high pressure x-ray study of 2,5-di(4-pyridyl)-1,3,4-oxadiazole up to 2.5 GPa are presented and discussed. Parameters for the Murnaghan equation of state are derived. The bulk modulus amounts to K{sub 0} = 4.6 {+-} 0.3 GPa and its pressure derivative to K{sub 0}{sup '} = 7.4 {+-} 0.6. These values are comparable to values of other diphenyl-1,3,4-oxadiazoles. The anisotropy of the compression is analysed using the strain tensor and discussed based on the anisotropy of the intermolecular interactions.

Orgzall, Ingo [Institut fuer Duennschichttechnologie und Mikrosensorik e. V., Kantstrasse 55, D-14513 Teltow (Germany); Franco, Olga [Universitaet Potsdam, Institut fuer Physik, Am Neuen Palais 10, D-14469 Potsdam (Germany); Schulz, Burkhard [Universitaet Potsdam, Institut fuer Physik, Am Neuen Palais 10, D-14469 Potsdam (Germany)

2006-06-14

100

Mode-specific vibrational energy relaxation of amide I' and II' modes in N-methylacetamide/water clusters: intra- and intermolecular energy transfer mechanisms.  

Science.gov (United States)

The mode-specific vibrational energy relaxation of the amide I' and amide II' modes in NMA-d(1)/(D(2)O)(n) (n = 0-3) clusters were studied using the time-dependent perturbation theory at the B3LYP/aug-cc-pvdz level. The amide modes were identified for each cluster based on the potential energy distribution of each mode. The vibrational population relaxation time constants were derived for the amide I' and II' modes. Results for the amide I' mode relaxation of NMA-d(1)/(D(2)O)(3) agree well with previous experimental results. The energy relaxation pathways were identified, and both intra- and intermolecular mechanisms were found to be important. The amide II' mode was identified in the energy transfer pathways from the excited amide I' mode of NMA-d(1)/(D(2)O)(n) (n = 1-3) clusters. The modes associated with methyl group deformation were found to play a role in the mechanism of energy transfer from both excited amide I' and II' modes. The kinetics of energy flow in the cluster were examined by solving a master equation describing the vibrational energy relaxation process from excited system mode as a multistep reaction with the third order Fermi resonance parameters as the reaction rate constants. The intramolecular energy transfer mechanism was found to dominate the short time energy flow dynamics, whereas the intermolecular mechanism was found to be dominant at longer times. PMID:19320512

Zhang, Yong; Fujisaki, Hiroshi; Straub, John E

2009-04-01

 
 
 
 
101

New solvation free energy function comprising intermolecular solvation and intramolecular self-solvation terms  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Solvation free energy is a fundamental thermodynamic quantity that should be determined to estimate various physicochemical properties of a molecule and the desolvation cost for its binding to macromolecular receptors. Here, we propose a new solvation free energy function through the improvement of the solvent-contact model, and test its applicability in estimating the solvation free energies of organic molecules with varying sizes and shapes. This new solvation free energy...

2013-01-01

102

Intermolecular interactions of liquid dichloromethane and equilibrium properties of liquid{endash}vapor and liquid{endash}liquid interfaces: A molecular dynamics study  

Energy Technology Data Exchange (ETDEWEB)

Extensive molecular dynamics simulations are carried out to study the molecular interactions, liquid states, and liquid/vapor properties of dichloromethane. The study is also extended to the equilibrium properties of the liquid/liquid interface of water-dichloromethane. The intermolecular interactions among water, dichloromethane, and water-dichloromethane are described using our polarizable potential models. The equilibrium properties of liquid dichloromethane, including the radial distribution functions, the intermolecular structural factor, the self-diffusion coefficient, and the dielectric constant, are evaluated. The dielectric constant is computed using Ewald summation techniques and the computed result compared reasonably well with the available experimental data. Properties such as surface tensions and density profiles of liquid/vapor dichloromethane are evaluated. We found that the computed surface tensions for several temperatures are in excellent agreement with experimental data. The computed density profile of the liquid/liquid interface of water-dichloromethane is averaged over 1 ns and we found the computed profile to be quite smooth and stable. The effect of polarization on the liquid/liquid interfacial equilibrium properties is evaluated by computing the dipole moments of water and dichloromethane molecules as a function of the distance normal to the interface. We found that these values deviated significantly from the simulations that are based on nonpolarizable potential models. We attribute these observations to the changes in the electric fields around the water and dichloromethane molecules near the interface. {copyright} {ital 1999 American Institute of Physics.}

Dang, L.X. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

1999-05-01

103

Characterization the effects of structure and energetics of intermolecular interactions on the oligomerization of peptides in aqueous 2, 2, 2-trifluoroethanol via circular dichroism and nuclear magnetic resonance spectroscopy.  

Science.gov (United States)

Intermolecular interactions are of fundamental importance to fully comprehend a wide range of protein behaviors such as oligomerization, folding and recognition. Two peptides, NPY([18-36]) and NPY([15-29]), segmented from human neuropeptide Y (hNPY), were synthesized in this work to study the interaction between species. Information about intermolecular interactions was extracted from their oligomerizing behaviors. The results from CD and NMR showed that the addition of 2, 2, 2-trifluoroethanol (TFE) induces a stable helix in each peptides and an extended helix in NPY([18-36]), formed between residues 30-36. Pulsed field gradient NMR data revealed that NPY([15-29]) forms a larger oligomer at lower temperatures and continuously dissociates into the monomeric form with increasing temperature. NPY([18-36]) was also found to undergo an enhanced interaction with TFE and a more favorable self-association at higher temperatures. We characterized the changes of oligomerized states with respect to temperature to infer the effects of entropy and interaction energy on the association-dissociation equilibrium. As shown by NPY([15-29]), deletion of helical secondary structure or residues from the C-terminal segment may disrupt the solvation by TFE and results in entropy increase as the oligomer dissociates. Unlike that in NPY([15-29]), the extended helix in NPY([18-36]) improves the binding of TFE, and as a result, entropy is gained via the transfer of the TFE cluster from the interface between monomeric peptides into the bulk solvent. This observation suggests that the oligomerized state may be modulated by the entropy and energetics contributed by helical segments in the oligomerization process. PMID:22311423

Lee, Chang-Shin; Tung, Wei-Cheng; Luo, Wan-Chi

2012-03-01

104

Multibody effects in intermolecular interactions and reaction pathways for catalytic processes. Part II the contributions of Sidonio Castillo  

Directory of Open Access Journals (Sweden)

Full Text Available Aquí continuaremos la revisión del trabajo de Octavio Novaro y sus colaboradores en los importantes campos de la no aditividad de las interacciones intermoleculares y de la catálisis, enfatizando las contribuciones de Sidonio Castillo que resultaron altamente útiles en este esfuerzo conjunto, antes de su prematuro fallecimiento. Sus primeros trabajos, con reconocidos científico polacos en los trímeros de metano y amoniaco y con coautores ingleses en trimeros y tetrámeros de fósforo y nitrógeno, serán presentados primero, seguidos de sus estudios sobre la activación catalítica de moléculas de metáno, silano y germano (de alto potencial en aplicaciones valiosas. Sus primeros trabajos en catálisis formaron parte de su tesis doctoral dirigida por O. Novaro y los últimos fueronconsecuencia de las tesis doctorales que el Dr. Castillo dirigió a los otros dos coautores de esta revisión. Esta labor fue desgraciadamente interrumpida por la muerte de Sidonio. Así concluyó su corta pero brillante carrera.

H. Luna

2009-01-01

105

Polyelectrolyte and non-polyelectrolyte polyacrylamide copolymer solutions: the role of salt on the intra- and intermolecular interactions  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Poli(acrilamida-co-dihexilacrilamida) (PAHM-0) e poli(acrilamida-co-acrilato de sódio-co-dihexilacrilamida) (PAHM-21) foram estudadas por espalhamento de raios-X a baixos ângulos (SAXS), espalhamento de luz (LS) e reologia. Os resultados de SAXS ressaltaram o caráter polieletrolítico da PAHM-21, com [...] uma conformação altamente estendida em solução aquosa devido às repulsões entre as cargas, enquanto a PAHM-0 tem uma conformação em novelo aleatório. As medidas de LS indicaram que a PAHM-0 forma aglomerados intermoleculares em solução, na presença e na ausência de sal, mesmo com um conteúdo hidrofóbico menor que o descrito na literatura para poliacrilamidas associativas. Contudo, os resultados reológicos mostraram que, apesar de haver associação hidrofóbica, não há um aumento da viscosidade. Os resultados de LS da PAHM-21 sugerem que esse polímero forma, predominantemente, associações intramoleculares na presença de sais. Além disso, as medidas viscosimétricas mostram que a sua viscosidade diminui com a blindagem das cargas pela adição de sais. Abstract in english Poly(acrylamide-co-dihexylacrylamide) (PAHM-0) and poly(acrylamide-co-sodium acrylate-co-dihexylacrylamide) (PAHM-21) were studied through small-angle X-ray scattering (SAXS), light scattering (LS) and rheology. SAXS results highlighted the polyelectrolyte character of PAHM-21, with highly extended [...] conformation in aqueous solution owing to charge repulsion, while the PAHM-0 has a coil conformation. LS measurements indicated that PAHM-0 makes intermolecular clusters in solution, in presence and absence of salt, even with a lower hydrophobic content than that described in the literature to the associative polyacrylamides. However, the rheological results showed that there is not an enhancement of the viscosity although hydrophobic association takes place. LS results for PAHM-21 suggest that this polymer makes intramolecular associations mainly in the presence of salts. Furthermore, the viscosity measurements show that its viscosity decreases due to screening of the charges by the addition of salts.

Maia, Ana M. S.; Villetti, Marcos A.; Borsali, Redouane; Balaban, Rosangela C..

106

Singlet-singlet intermolecular optical energy transfer from naphthalene to benzophenone in the vapor phase  

Science.gov (United States)

By using the exothermic energy transfer as a function of pressure, the rate constant for diffusion was evaluated for benzophenone/naphthalene and naphthalene/benzophenone systems. In principle the optical energy absorbed by a complex molecule raises that molecule to one of its excited states, and afterwards this excitation energy decays through the different relaxation channels. Initially, electronically excited naphthalene "S 1" state emits photons in the fluorescence band of naphthalene and these emitted photons, as a stream of particles, are absorbed by the acceptor molecule benzophenone, then excited benzophenone fluoresces. In this investigation, sensitized fluorescence decay times in different conditions were measured for naphthalene-benzophenone system in the vapor phase, and found to be 12 ± 1 ns. The ultraviolet-visible spectra of the system in the vapor phase at room temperature conditions were broad and structureless.

Bayrakçeken, Fuat

2008-11-01

107

Intramolecular photo-switching and intermolecular energy transfer as primary photoevents in photoreceptive processes: The case of Euglena gracilis  

Energy Technology Data Exchange (ETDEWEB)

In this paper we report the results of measurements performed by FLIM on the photoreceptor of Euglenagracilis. This organelle consists of optically bistable proteins, characterized by two thermally stable isomeric forms: A{sub 498,} non fluorescent and B{sub 462}, fluorescent. Our data indicate that the primary photoevent of Euglena photoreception upon photon absorption consists of two contemporaneous different phenomena: an intramolecular photo-switch (i.e., A{sub 498} becomes B{sub 462}), and a intermolecular and unidirectional Forster-type energy transfer. During the FRET process, the fluorescent B{sub 462} form acts as donor for the non-fluorescent A{sub 498} form of the protein nearby, which acts as acceptor. We hypothesize that in nature these phenomena follow each other with a domino progression along the orderly organized and closely packed proteins in the photoreceptor layer(s), modulating the isomeric composition of the photoreceptive protein pool. This mechanism guarantees that few photons are sufficient to produce a signal detectable by the cell.

Mercatelli, Raffaella; Quercioli, Franco [Istituto Sistemi Complessi, CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); Barsanti, Laura; Evangelista, Valter [Istituto di Biofisica, CNR, Via Moruzzi 1, 56124 Pisa (Italy); Coltelli, Primo [ISTI, CNR, Via Moruzzi 1, 56124 Pisa (Italy); Passarelli, Vincenzo; Frassanito, Anna Maria [Istituto di Biofisica, CNR, Via Moruzzi 1, 56124 Pisa (Italy); Gualtieri, Paolo, E-mail: paolo.gualtieri@pi.ibf.cnr.it [Istituto di Biofisica, CNR, Via Moruzzi 1, 56124 Pisa (Italy)

2009-07-24

108

Studies on tolfenamic acid-chitosan intermolecular interactions: effect of pH, polymer concentration and molecular weight.  

Science.gov (United States)

Solid-state properties of tolfenamic acid (TA) and its complexes with chitosan (CT) have been studied. Effect of medium pH, molecular weight of polymer and its different concentrations on these TA-CT complexes were studied in detail. Low and medium molecular weight CT have been used in different ratios at pH ranging from 4 to 6 and freeze-drying technique has been employed to modify the appearance of crystalline TA. Physical properties of the formed complexes have been studied by employing X-ray diffraction, differential scanning calorimetry and scanning electron microscopy; chemical structure has been studied using Fourier transform infrared spectroscopy. The results showed that both forms of the polymer exhibited complete conversion in 1:8 ratio at pH 4, 1:4 at pH 5 and 1:1 at pH 6 indicating a marked effect of pH on drug-polymer complexation. The percent crystallinity calculations indicated low molecular weight CT slightly more effective than the other form. No changes in the complexes have been observed during the 12 week storage under controlled conditions. Both forms of CT at different pH values indicated retardation of recrystallization in TA during cooling of the melt from 1:1 ratios exhibiting formation of strong intermolecular hydrogen bonding between the drug and the polymer. PMID:23620261

Ahmed, Sofia; Sheraz, Muhammad Ali; Rehman, Ihtesham Ur

2013-06-01

109

Intermolecular effects in the pulsed field ionization zero kinetic energy photoelectron spectra of molecular  

International Nuclear Information System (INIS)

Pulsed field ionization zero kinetic energy electron spectroscopy (PFI-ZEKE) involves the electric field ionization of high principal quantum number Rydberg states approximately one microsecond after optical excitation. Only recently has it been appreciated that in most cases these Rydberg states should have lifetimes much shorter than one microsecond if purely intramolecular behavior is considered (due to the autoionization and predissociation decay channels). It has been hypothesized that weak electric DC-fields and surrounding ions can stabilize these states against decay. The PFI-ZEKE spectra corresponding to highly vibrationally excited ionic cores of H2+ (v+ = 13, 15) have been observed. In this case the Rydberg states responsible for the field ionization signal require some form of stabilization against vibrational autoionization. In this talk it is reported that ion-density influence the H2 PFI-ZEKE lineshapes in a dramatic manner. This is shown to be consistent with the ion-density stabilization mechanism

1996-05-01

110

Black Hole Interaction Energy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The interaction energy between two black holes at large separation distance is calculated. The first term in the expansion corresponds to the Newtonian interaction between the masses. The second term corresponds to the spin-spin interaction. The calculation is based on the interaction energy defined on the two black holes initial data. No test particle approximation is used. The relation between this formula and cosmic censorship is discussed.

Dain, Sergio

2002-01-01

111

In-vitro anti-proliferative and anti-oxidant activity of galangin, fisetin and quercetin: role of localization and intermolecular interaction in model membrane.  

Science.gov (United States)

Flavonols are an important class of naturally occurring molecules and are known for their pharmacological activity. The activity is associated with the ability of flavonols to influence membrane-dependent processes. We have investigated the in-vitro anti-proliferative and anti-oxidant activity of galangin (GLN), fisetin (FTN) and quercetin (QTN), which possess variable number of phenolic hydroxyl groups. An attempt has been made to correlate the biological activity of these molecules with their interaction and localization in dipalmitoyl phosphatidyl choline (DPPC) bilayers, using differential dcanning calorimetry (DSC) and nuclear magnetic resonance (NMR) methods. Results indicate that GLN interacts to the alkyl chains of the lipid bilayer involving hydrophobic interactions. FTN and QTN interact with head region and sn-1-glycero region involving hydrogen bonding. Ring current induced chemical shifts of lipid protons, due to intermolecular interaction indicate that GLN acquires a parallel orientation with respect to the bilayer normal whereas FTN and QTN resume a mixed orientation. The membrane binding constants of these molecules are in the order GLN > QTN > FTN. It has been shown that the number and position of hydroxyl groups in these molecules play an important role in membrane binding and thereby in biological activity. PMID:24727463

Sinha, Ragini; Srivastava, Sudha; Joshi, Akshada; Joshi, Urmila J; Govil, Girjesh

2014-05-22

112

Morphology and the Strength of Intermolecular Contact in Protein Crystals  

Science.gov (United States)

The strengths of intermolecular contacts (macrobonds) in four lysozyme crystals were estimated based on the strengths of individual intermolecular interatomic interaction pairs. The periodic bond chain of these macrobonds accounts for the morphology of protein crystals as shown previously. Further in this paper, the surface area of contact, polar coordinate representation of contact site, Coulombic contribution on the macrobond strength, and the surface energy of the crystal have been evaluated. Comparing location of intermolecular contacts in different polymorphic crystal modifications, we show that these contacts can form a wide variety of patches on the molecular surface. The patches are located practically everywhere on this surface except for the concave active site. The contacts frequently include water molecules, with specific intermolecular hydrogen-bonds on the background of non-specific attractive interactions. The strengths of macrobonds are also compared to those of other protein complex systems. Making use of the contact strengths and taking into account bond hydration we also estimated crystal-water interfacial energies for different crystal faces.

Matsuura, Yoshiki; Chernov, Alexander A.

2002-01-01

113

Structural analysis of intermolecular interactions in the kinesin adaptor complex fasciculation and elongation protein zeta 1/ short coiled-coil protein (FEZ1/SCOCO).  

Science.gov (United States)

Cytoskeleton and protein trafficking processes, including vesicle transport to synapses, are key processes in neuronal differentiation and axon outgrowth. The human protein FEZ1 (fasciculation and elongation protein zeta 1 / UNC-76, in C. elegans), SCOCO (short coiled-coil protein / UNC-69) and kinesins (e.g. kinesin heavy chain / UNC116) are involved in these processes. Exploiting the feature of FEZ1 protein as a bivalent adapter of transport mediated by kinesins and FEZ1 protein interaction with SCOCO (proteins involved in the same path of axonal growth), we investigated the structural aspects of intermolecular interactions involved in this complex formation by NMR (Nuclear Magnetic Resonance), cross-linking coupled with mass spectrometry (MS), SAXS (Small Angle X-ray Scattering) and molecular modelling. The topology of homodimerization was accessed through NMR (Nuclear Magnetic Resonance) studies of the region involved in this process, corresponding to FEZ1 (92-194). Through studies involving the protein in its monomeric configuration (reduced) and dimeric state, we propose that homodimerization occurs with FEZ1 chains oriented in an anti-parallel topology. We demonstrate that the interaction interface of FEZ1 and SCOCO defined by MS and computational modelling is in accordance with that previously demonstrated for UNC-76 and UNC-69. SAXS and literature data support a heterotetrameric complex model. These data provide details about the interaction interfaces probably involved in the transport machinery assembly and open perspectives to understand and interfere in this assembly and its involvement in neuronal differentiation and axon outgrowth. PMID:24116125

Alborghetti, Marcos Rodrigo; Furlan, Ariane da Silva; da Silva, Júlio César; Sforça, Maurício Luís; Honorato, Rodrigo Vargas; Granato, Daniela Campos; dos Santos Migueleti, Deivid Lucas; Neves, Jorge L; de Oliveira, Paulo Sergio Lopes; Paes-Leme, Adriana Franco; Zeri, Ana Carolina de Mattos; de Torriani, Iris Concepcion Linares; Kobarg, Jörg

2013-01-01

114

Tailored donor-acceptor polymers with an A-D1-A-D2 structure: controlling intermolecular interactions to enable enhanced polymer photovoltaic devices.  

Science.gov (United States)

Extensive efforts have been made to develop novel conjugated polymers that give improved performance in organic photovoltaic devices. The use of polymers based on alternating electron-donating and electron-accepting units not only allows the frontier molecular orbitals to be tuned to maximize the open-circuit voltage of the devices but also controls the optical band gap to increase the number of photons absorbed and thus modifies the other critical device parameter-the short circuit current. In fact, varying the nonchromophoric components of a polymer is often secondary to the efforts to adjust the intermolecular aggregates and improve the charge-carrier mobility. Here, we introduce an approach to polymer synthesis that facilitates simultaneous control over both the structural and electronic properties of the polymers. Through the use of a tailored multicomponent acceptor-donor-acceptor (A-D-A) intermediate, polymers with the unique structure A-D1-A-D2 can be prepared. This approach enables variations in the donor fragment substituents such that control over both the polymer regiochemistry and solubility is possible. This control results in improved intermolecular ?-stacking interactions and therefore enhanced charge-carrier mobility. Solar cells using the A-D1-A-D2 structural polymer show short-circuit current densities that are twice that of the simple, random analogue while still maintaining an identical open-circuit voltage. The key finding of this work is that polymers with an A-D1-A-D2 structure offer significant performance benefits over both regioregular and random A-D polymers. The chemical synthesis approach that enables the preparation of A-D1-A-D2 polymers therefore represents a promising new route to materials for high-efficiency organic photovoltaic devices. PMID:24697300

Qin, Tianshi; Zajaczkowski, Wojciech; Pisula, Wojciech; Baumgarten, Martin; Chen, Ming; Gao, Mei; Wilson, Gerry; Easton, Christopher D; Müllen, Klaus; Watkins, Scott E

2014-04-23

115

Landau-Zener tunneling in the presence of weak intermolecular interactions in a crystal of Mn4 single-molecule magnets  

CERN Document Server

A Mn4 single-molecule magnet (SMM), with a well isolated spin ground state of S = 9/2, is used as a model system to study Landau-Zener (LZ) tunneling in the presence of weak intermolecular dipolar and exchange interactions. The anisotropy constants D and B are measured with minor hysteresis loops. A transverse field is used to tune the tunnel splitting over a large range. Using the LZ and inverse LZ method, it is shown that these interactions play an important role in the tunnel rates. Three regions are identified: (i) at small transverse fields, tunneling is dominated by single tunnel transitions; (ii) at intermediate transverse fields, the measured tunnel rates are governed by reshuffling of internal fields, (iii) at larger transverse fields, the magnetization reversal starts to be influenced by the direct relaxation process, and many-body tunnel events may occur. The hole digging method is used to study the next-nearest neighbor interactions. At small external fields, it is shown that magnetic ordering occ...

Wernsdorfer, W; Vinslava, A; Christou, G

2005-01-01

116

Relationship between molecular weight of poly(ethylene)glycol and intermolecular interaction of Taka-amylase A monomers  

Science.gov (United States)

Dynamic and static light scattering investigations of Taka-amylase A (TAA) protein monomers were done using solutions containing poly(ethylene)glycol (PEG) with molecular weights of 1500, 4000, 8000, and 20 000. The anomalies observed in a previous study using a weight of 8000, in which the hydrodynamic TAA monomer radius at a zero protein concentration and the molecular weight of the monomers decreased when the PEG concentration was increased, were observed for all four weights. These anomalies became more pronounced as the PEG molecular weight was increased. The overall interaction parameter did not move further in the direction of the attractive force despite an increase in the PEG concentration from 6% to 12.5% for the PEG 8000 and 20 000 solutions. This was due to the change in the relative contributions of the static structure factor (direct interaction) and the hydrodynamic interaction factor (indirect interaction) against the overall interaction parameter. For the PEG 1500 and 4000 solutions, the change in the overall interaction parameter with an increase in the PEG concentration was controlled by changing the static structure factor. For the PEG 8000 and 20 000 solutions, a change in the hydrodynamic interaction factor with an increase in the PEG concentration offset the change in the static structure factor, unexpectedly resulting in the overall interaction parameter being independent of the PEG concentration. This suggests that the scale and density of a PEG network structure, which are thought to be the origin of the observed anomalies, change nonlinearly with the PEG molecular weight.

Onuma, Kazuo; Furubayashi, Naoki; Shibata, Fujiko; Kobayashi, Yoshiko; Kaito, Sachiko; Ohnishi, Yuki; Inaka, Koji

2010-04-01

117

A quantum-chemical validation about the formation of hydrogen bonds and secondary interactions in intermolecular heterocyclic systems  

Directory of Open Access Journals (Sweden)

Full Text Available We have performed a detailed theoretical study in order to understand the charge density topology of the C2H4O···C2H2 and C2H4S···C2H2 heterocyclic hydrogen-bonded complexes. Through the calculations derived from Quantum Theory of Atoms in Molecules (QTAIM, it was observed the formation of hydrogen bonds and secondary interactions. Such analysis was performed through the determination of optimized geometries at B3LYP/6-31G(d,p level of theory, by which is that QTAIM topological operators were computed, such as the electronic density ?(r, Laplacian Ñ2?(r, and ellipticity ?. The examination of the hydrogen bonds has been performed through the measurement of ?(r, Ñ2?(r and ? between (O···H—C and (S···H—C, whereas the secondary interaction between axial hydrogen atoms H? and carbon of acetylene. In this insight, it was verified the existence of secondary interaction only in C2H4S···C2H2 complex because its structure is propitious to form multiple interactions.

Boaz Galdino Oliveira

2009-08-01

118

Synthesis, crystal structure and intermolecular magnetic interactions of a new N-TEMPO-3,5-di- tert-butylsalicylaldimine radical  

Science.gov (United States)

A new N-TEMPO-3,5-di- tert-butylsalicylaldimine radical ( 1) has been synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR, UV-vis, and EPR spectroscopy and temperature dependent magnetic susceptibility. X-ray diffraction revealed that H-atoms of ?-CH in TEMPO and CH 3 in salicylaldimine moieties, are located in close contact with the neighboring N-O radical group in crystal 1. The temperature dependence of the magnetic susceptibility ( ?m) of 1 has been fitted by the Curie-Weiss law with ? = -0.3 K within 10-300 K, suggesting the presence of a weak intermolecular antiferromagnetic interaction between radical centers at T < 10 K. It has been demonstrated that radical 1 possesses crystal structure involving co-existence of antiferromagnetic and ferromagnetic interactions through C-H⋯O-N rad contacts of ?-CH and tBu groups hydrogen atoms, in which the former path dominates over the latter.

Kasumov, Veli T.; Uçar, Ibrahim; Bulut, Ahmet; Yerli, Yusuf

2011-10-01

119

"1"2C/"1"3C and H/D vapor pressure isotope effects of fluoroform: intermolecular interactions in liquid fluoroform  

International Nuclear Information System (INIS)

A precision cryostat of the Bigeleisen-Brooks-Ribnikar-Ishida (BBIR) type with associated vacuum systems has been constructed and the appropriate temperature/pressure measurement and control systems designed and implemented. Various improvements in the cryostat design were incorporated in order to facilitate the assembly and repair processes. A major design change involved the incorporation of a digital stand alone computer to control cryostat operations. This apparatus was used to measure the "1"2C/"1"3C and H/D Vapor Pressure Isotope Effects of Fluoroform. Analysis of the measured VPIE results, in light of existing experimental data and theories, has demonstrated the need of a temperature dependent liquid force field, specifically a temperature-dependent interaction force constant between the C-H stretching motion and translational motion in the direction of the figure axis of CHF_3. This result is consistent with the observed spectroscopic data and vibrational and configurational models of fluoroform dimers. The intermolecular interaction is believed to be a weak hydrogen-bond in nature

1981-01-01

120

STUDY OF INTERMOLECULAR FORCES AND INTERACTIONS IN BINARY LIQUID MIXTURE CHLOROFORM, ACETONE, M-XYLENE, AND CYCLOHEXANE IN DMSO  

Directory of Open Access Journals (Sweden)

Full Text Available Thermodynamic studies like density ( ? , ultrasonic speed ( u and excess molar volume ( Vm E of binary liquid mixture of Chloroform ,Acetone, m- Xylene ,Cyclohexane+ DMSO have been carried out over the different range of composition at 308.15 K. Thermodynamic parameters like isentropic compressibility Ks , interaction parameter, ?12 , Flory parameters, coefficients, Ai and standard deviations, ? (Y E have been computed from experimental findings.

Dheeraj Kumar

2014-05-01

 
 
 
 
121

Studies on the electronic structure and intermolecular interactions of diacetyl-, and methylglyoxal- bis(thiosemicarbazone)copper(II) complexes  

Science.gov (United States)

The electronic structure of the title complexes are studied by e.p.r. and electronic spectra in DMF solution (300 and 100 K) as well as in magnetically diluted powder sample. It is found that the electronic structure is determined mainly by the unit CuN 2S 2 of the complex. The interaction of the complexes with some Lewis acids is also studied. The formation of D-A complex with relatively weak acids is observed. The strong Lewis acids destroy the complexes.

Yordanov, N. D.; Batchvarova, M. T.

1984-03-01

122

Ion-built-in covalent-cyclic model in the MNDO calculations of intermolecular interactions in heterogeneous systems  

International Nuclear Information System (INIS)

The MNDO calculation scheme has been modified for the case of a cyclic cluster model for periodic infinite structure (polymers, crystals). Two methods of presetting cyclic boundary conditions are suggested. In the framework of the approximations suggested an expression for total energy of ion-built-in covalent-cyclic cluster, required for optimization of geometry of objects simulated, has been obtained. The method has been used for the calculation of boron nitride hexagonal structure. 21 refs.; 2 tabs

1995-01-01

123

Intermolecular C-H···O, Cl···Cl and ?-? interactions in the 2-dichloromethyl derivative of vitamin K3.  

Science.gov (United States)

The title 1,4-naphthoquinone, 2-dichloromethyl-3-methyl-1,4-dihydronaphthalene-1,4-dione, C12H8Cl2O2, is a chlorinated derivative of vitamin K3, which is a synthetic compound also known as menadione. Molecules of (I) are planar and lie on a crystallographic mirror plane (Z' = 0.5) in the space group Pnma. They are connected to each other by C-H···O hydrogen bonds, forming two-dimensional layers parallel to the ac plane. In addition, Cl···Cl and ?-? interactions link adjacent molecules in different layers, thus forming zigzag ribbons along the b axis, such that a three-dimensional architecture is generated. PMID:24311513

Soave, Raffaella; Colombo, Pietro

2013-12-15

124

Intermolecular interaction of voriconazole analogues with model membrane by DSC and NMR, and their antifungal activity using NMR based metabolic profiling.  

Science.gov (United States)

The development of novel antifungal agents with high susceptibility and increased potency can be achieved by increasing their overall lipophilicity. To enhance the lipophilicity of voriconazole, a second generation azole antifungal agent, we have synthesized its carboxylic acid ester analogues, namely p-methoxybenzoate (Vpmb), toluate (Vtol), benzoate (Vbz) and p-nitrobenzoate (Vpnb). The intermolecular interactions of these analogues with model membrane have been investigated using nuclear magnetic resonance (NMR) and differential scanning calorimetric (DSC) techniques. The results indicate varying degree of changes in the membrane bilayer's structural architecture and physico-chemical characteristics which possibly can be correlated with the antifungal effects via fungal membrane. Rapid metabolite profiling of chemical entities using cell preparations is one of the most important steps in drug discovery. We have evaluated the effect of synthesized analogues on Candida albicans. The method involves real time (1)H NMR measurement of intact cells monitoring NMR signals from fungal metabolites which gives Metabolic End Point (MEP). This is then compared with Minimum Inhibitory Concentration (MIC) determined using conventional methods. Results indicate that one of the synthesized analogues, Vpmb shows reasonably good activity. PMID:24012381

Kalamkar, Vaibhav; Joshi, Mamata; Borkar, Varsha; Srivastava, Sudha; Kanyalkar, Meena

2013-11-01

125

Refined ab initio intermolecular ground-state potential energy surface for the He-C2H2 van der Waals complex  

DEFF Research Database (Denmark)

A refined CCSD(T) intermolecular potential energy surface is developed for the He-C2H2 van der Waals complex. For this, 206 points on the intermolecular potential energy surface, evaluated using the CCSD(T) method and the aug-cc-pVQZ basis set extended with a set of 3s3p2d1f1g midbond functions, are fitted to a 15-parameter analytic function. The potential is characterised by minima of-24.21 cm-1 at distances between the rare gas atom and the C2H2 centre of mass of 4.3453 AÌ?, and with the complex in a linear configuration. At intermediate distances the surface is rather similar to that developed previously by Munteanu and Fernández (J. Chem. Phys., 123, 014309, 2005) but differs notably at short range. The improved potential energy surface should, therefore, be particularly useful for computations of collision line broadening. Dynamical calculations of a number of rovibrational bound state energies and wave functions are presented. Inspection of the nodal surfaces of several low lying excited states shows that the complex is close to the free rotor limit.

Fernández, Berta; Henriksen, Christian

2013-01-01

126

Dimeric interaction between the cytoplasmic domains of the Na+/H+ exchanger NHE1 revealed by symmetrical intermolecular cross-linking and selective co-immunoprecipitation.  

Science.gov (United States)

To investigate the oligomeric structure of Na(+)/H(+) exchanger 1 (NHE1), permeabilized cells and membranes from cells expressing NHE1 variants were treated with the oxidizing agent Cu(2+)/o-phenanthroline or the bifunctional sulfhydryl reagent methanethiosulfonate. These treatments resulted in symmetrical intermolecular cross-linking at intrinsic (Cys(794) and Cys(561)) or 15 exogenous cysteine residues introduced into the distal carboxyl- (C-) terminal cytoplasmic domain (after aa 600) but not at intrinsic Cys(538) because of masking by its tight association with calcineurin B-homologous protein. Cross-linking was abolished in membranes solubilized with sodium dodecyl sulfate, which dissociates oligomeric NHE1, while it was preserved in those treated with Triton X-100. In addition, treatment with cross-linkers did not produce the tetrameric forms of NHE1 mutants with two cysteine residues. Thus, cross-linking presumably occurs between adjacent C-termini of the NHE1 dimer but not by a stochastic process via random collision of NHE1 molecules. The observations suggest that at least the distal C-termini of the NHE1 dimer are flexible or mobile and are thereby capable of easily making contact with each other over the large cytoplasmic portion of the molecule. Furthermore, co-immunoprecipitation experiments showed that the proximal C-termini (aa 503-580) have a strong propensity to interact directly with each other in parallel. Deletion of aa 562-579 resulted in disruption of disulfide cross-linking between the C-termini and markedly reduced the intracellular pH sensitivity of Na(+)/H(+) exchange, suggesting that the dimeric interaction in this region may control the pH-dependent regulation of NHE1. PMID:15323573

Hisamitsu, Takashi; Pang, Tianxiang; Shigekawa, Munekazu; Wakabayashi, Shigeo

2004-08-31

127

Theoretical study of intermolecular energy transfer involving electronically excited molecules: He("1S) + H_2(B "1?/sub u/"+)  

International Nuclear Information System (INIS)

To further understanding of gas phase collision dynamics involving electronically-excited molecules, a fully quantum mechanical study of He + H_2(B "1?/sub u/"+) was undertaken. Iterative natural orbital configuration interaction (CI) calculations were performed to obtain the interaction potential between He and H_2(B "1?/sub u/"+). The potential energy surface (PES) is highly anisotropic and has a van der Waals well of about 0.03 eV for C/sub 2v/ approach. Avoided PES crossings occur with He + H_2(E,F "1?/sub g/"+) and with He + H_2(X "1?/sub g/"+) and cause a local maximum and a deep minimum in the He + H_2(B "1?/sub u/"+) PES, respectively. The crossing with He + H_2(X "1?/sub g/"+) provides a mechanism for fluorescence quenching. The computed CI energies were combined with previous multi-reference double excitation CI calculations and fit with analytic functions for convenience in scattering calculations. Accurate dipole polarizabilities and quadrupole moment of H_2(B "1?/sub u/"+) were computed for use in the multipole expansion, which is the analytic form of the long-range PES. 129 refs., 28 figs., 35 tabs

1986-01-01

128

Preparation and characterization of co-amorphous Ritonavir-Indomethacin systems by solvent evaporation technique: Improved dissolution behavior and physical stability without evidence of intermolecular interactions.  

Science.gov (United States)

The aim of this study was to stabilize the amorphous form of Ritonavir (RTV) a BCS class-II drug with known amorphous stabilizing small molecule Indomethacin (IND) by co-amorphous technology. The co-amorphous samples were prepared by solvent evaporation technique in the molar ratios RTV:IND (2:1), RTV:IND (1:1), RTV:IND (1:2) and their amorphous nature was confirmed by XRPD, DSC and FT-IR. Physical stability studies were carried out at temp 25°C and 40°C for maximum up to 90days under dry conditions. Solubility and dissolution testing were carried out to investigate the dissolution advantage of prepared co-amorphous systems. The amorphous mixtures of all tested molar ratios were found to become amorphous after solvent evaporation. The same was confirmed by detecting halo pattern in diffractograms of co-amorphous mixtures. The Tg values of all three systems were found to be more than 40°C, the highest being 51.88°C for RTV:IND (2:1) system. Theoretical Tg values were calculated by Gordon-Taylor equation. Insignificant deviation of theoretical Tg values from that of practical one, corroborated by FT-IR studies showed no evidence of intermolecular interactions between RTV and IND. Almost 3-folds increase in the solubility for both amorphous RTV and IND was found as compared to their respective crystalline counterparts. The study demonstrated significant increase in the dissolution rate as well as increase in the total amount of drug dissolved for amorphous RTV, however it failed to demonstrate any significant improvement in the dissolution behavior of IND. PMID:24878386

Dengale, Swapnil J; Ranjan, Om Prakash; Hussen, Syed Sajjad; Krishna, B S M; Musmade, Prashant B; Gautham Shenoy, G; Bhat, Krishnamurthy

2014-10-01

129

Intermolecular interactions: basis set and intramolecular correlation effects on semiempirical methods. Application to (C_2H_2)_2, (C_2H_2)_3 and (C_2H_4)_2  

International Nuclear Information System (INIS)

A detailed study of the intrinsic consistency of the semiempirical method of P. Claverie namely, the effects of the basis set and intramolecular correlation on the multipole distributions of molecular subunits and the influence of the electronic population of each atom in the molecular subunit on its van der Waals radius, is performed on some van der Waals dimers. The validity, limits of this model and the appropriate way to use it is established. In particular, the dependence of the geometry and the interaction energy on the basis set chosen and the intramolecular correlation shows that the multipole distribution involved in the calculation of the electrostatic and polarization terms must be derived from a correlated wave function within an extended basis set. Associated to non local methods for finding stationary points, the method of P. Claverie reproduce reliably the intermolecular geometrical parameters observed for the equilibrium structures and the transition states of the dimer and trimer of acetylene. In addition, a study of the equilibrium structures of the ethylene dimer is presented, the aim of being to clarify the considerable uncertainty in their number and their geometry. (orig.)

1994-07-01

130

Influence of H/D - isotope substitution on structure-thermodynamic parameters of intermolecular interaction in methanol at 278-318 K  

International Nuclear Information System (INIS)

Influence of H/D - isotope substitution in methanol molecules on their geometric parameters and energy of interparticle interactions was considered. It is shown that deuteration involves reduction of volume occupied by one molecule in methanol structural matrix. The fact of differentiating action of isotope substitution on the character of distribution of specific and Van-der-Vaals interactions, which is pronounced in enhancement of the former and weakening of the latter, when deuterium is substituted for protium in the group forming hydrogen bonds and, vice versa, when alcohol is substituted for deuterium in methyl radical, was ascertained

2000-01-01

131

Energetics of Intermolecular Hydrogen Bonds in a Hydrophobic Protein Cavity  

Science.gov (United States)

This work explores the energetics of intermolecular H-bonds inside a hydrophobic protein cavity. Kinetic measurements were performed on the gaseous deprotonated ions (at the -7 charge state) of complexes of bovine ?-lactoglobulin (Lg) and three monohydroxylated analogs of palmitic acid (PA): 3-hydroxypalmitic acid (3-OHPA), 7-hydroxypalmitic acid (7-OHPA), and 16-hydroxypalmitic acid (16-OHPA). From the increase in the activation energy for the dissociation of the (Lg + X-OHPA)7- ions, compared with that of the (Lg + PA)7- ion, it is concluded that the -OH groups of the X-OHPA ligands participate in strong (5 - 11 kcal mol-1) intermolecular H-bonds in the hydrophobic cavity of Lg. The results of molecular dynamics (MD) simulations suggest that the -OH groups of 3-OHPA and 16-OHPA act as H-bond donors and interact with backbone carbonyl oxygens, whereas the -OH group of 7-OHPA acts as both H-bond donor and acceptor with nearby side chains. The capacity for intermolecular H-bonds within the Lg cavity, as suggested by the gas-phase measurements, does not necessarily lead to enhanced binding in aqueous solution. The association constant (Ka) measured for 7-OHPA [(2.3 ± 0.2) × 105 M-1] is similar to the value for the PA [(3.8 ± 0.1) × 105 M-1]; Ka for 3-OHPA [(1.1 ± 0.3) × 106 M-1] is approximately three-times larger, whereas Ka for 16-OHPA [(2.3 ± 0.2) × 104 M-1] is an order of magnitude smaller. Taken together, the results of this study suggest that the energetic penalty to desolvating the ligand -OH groups, which is necessary for complex formation, is similar in magnitude to the energetic contribution of the intermolecular H-bonds.

Liu, Lan; Baergen, Alyson; Michelsen, Klaus; Kitova, Elena N.; Schnier, Paul D.; Klassen, John S.

2014-05-01

132

Study of intermolecular interactions in the system of equilibrium catalytic transesterification of esters. 4. Fourier IR studies of the interaction of alcohols with esters  

International Nuclear Information System (INIS)

Interaction of alcohols ROH with esters PhCOOR (R = Me, n-Bu, n-C7H15) in binary mixtures and in solutions in non-polar solvents was studies over a wide temperature range by means of Fourier IR spectroscopy. Even with alcohol taken in a great excess, two bands are observed in the region of ?CO vibrations. The low-frequency band, correspond to the ester molecules bonded by hydrogen bonds of the C=O...HO type. The high-frequence band is shifted by 3-5 cm-1 with respect to the ester ?CO band. The discreteness of the shift, indicates that an H-complex of one more type is formed between the alcohol and the ester. The analysis of data available allows one to conclude that the complex formation involves the alkoxyl oxygen atom of the ester. The formation enthalpies were determined for H-bond of n-BuOH with the esters and with transesterification catalysts B(OBu)3

1993-04-01

133

Desensitization of metastable intermolecular composites  

Energy Technology Data Exchange (ETDEWEB)

A method to substantially desensitize a metastable intermolecular composite material to electrostatic discharge and friction comprising mixing the composite material with an organic diluent and removing enough organic diluent from the mixture to form a mixture with a substantially putty-like consistency, as well as a concomitant method of recovering the metastable intermolecular composite material.

Busse, James R. (South Fork, CO); Dye, Robert C. (Los Alamos, NM); Foley, Timothy J. (Los Alamos, NM); Higa, Kelvin T. (Ridgecrest, CA); Jorgensen, Betty S. (Jemez Springs, NM); Sanders, Victor E. (White Rock, NM); Son, Steven F. (Los Alamos, NM)

2011-04-26

134

Inhomogeneous and interacting vacuum energy  

CERN Document Server

Vacuum energy is a simple model for dark energy driving an accelerated expansion of the universe. If the vacuum energy is inhomogeneous in spacetime then it must be interacting. We present the general equations for a spacetime-dependent vacuum energy in cosmology, including inhomogeneous perturbations. We show how any dark energy cosmology can be described by an interacting vacuum+matter. Different models for the interaction can lead to different behaviour (e.g., sound speed for dark energy perturbations) and hence could be distinguished by cosmological observations. As an example we present the cosmic microwave microwave background anisotropies and the matter power spectrum for two different versions of a generalised Chaplygin gas cosmology.

De-Santiago, Josue; Wang, Yuting

2012-01-01

135

Frontier orbital symmetry control of intermolecular electron transfer  

Energy Technology Data Exchange (ETDEWEB)

Research continued on the study of intermolecular electron transfer. This report discusses the following topics: fluorescence quenching by electron transfer and the modification of quenching dynamics by solvent properties and net free energy change; transient absorption measurements following selective excitation of 1:1 EDA complex isomers; selective quenching of dual fluorescence from linked EDA systems; electron-transfer sensitized cycloreversion of rubrene endoperoxide; and vibronic modification of adiabatic requirements for intermolecular electron transfer. (CBS)

Stevens, B.

1990-11-01

136

Weak interactions at high energies  

International Nuclear Information System (INIS)

Review lectures are given on the experimental status of high energy weak interactions with a special emphasis on its relation to the physics of new particles. All previously presented data are included. Limitation is made to the charged current aspect of the neutrino interactions, with the main emphasis on the experimental data. Comparisons are made with the naive and four-quark models. 47 references

1976-11-01

137

Quantum mechanical calculations on weakly interacting complexes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Symmetry-adapted perturbation theory (SAPT) has been applied to compute the intermolecular potential energy surfaces and the interaction-induced electrical properties of weakly interacting complexes. Asymptotic (large R) expressions have been derived for the contributions to the collision-induced properties up to and including second order in the intermolecular potential. The computed interaction-induced polarizability for the helium diatom has been used in quantum-dynamical calculations of t...

Heijmen, Theodorus Gerardus Albertus

1998-01-01

138

Alternating 2,6-/3,5-substituted pyridine-acetylene macrocycles: ?-stacking self-assemblies enhanced by intermolecular dipole-dipole interaction.  

Science.gov (United States)

Macrocyclic compounds consisting of three 2,6-pyridylene and three 3,5-pyridylene units linked by acetylene bonds were synthesized by a Sonogashira reaction. The X-ray structures showed ?-stacked pairs of two macrocycles, in which a 2,6-pyridylene unit of the one molecule overlaps a 3,5-pyridylene of the other molecule because of dipole-dipole interaction. Atomic force microscope (AFM) measurements revealed fibril structures indicating the stacking of the rigid planar macrocycles. Hydrogen-bonding ability of the macrocyclic inside was demonstrated by the addition of octyl ?-D-glucopyranoside. PMID:24446734

Abe, Hajime; Ohtani, Kohei; Suzuki, Daiki; Chida, Yusuke; Shimada, Yuta; Matsumoto, Shinya; Inouye, Masahiko

2014-02-01

139

Intermolecular interactions in the chiral and racemic forms of 3-hydroxy-2-(1-oxoisoindolin-2-yl)butanoic acid derived from threonine  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The title compounds, C??H??NO?, are derived from L-threonine and DL-threonine, respectively. Hydrogen bonding in the chiral derivative, (2S/3R)-3-hydroxy-2-(1-oxoisoindolin-2-yl)butanoic acid, consists of O-Hacid...Oalkyl-H...O=Cindole chains [O...O 2.659 (3) and 2.718 (3) Å], Csp³-H...O and three C-H...?arene interactions. In the (2R,3S/2S,3R) racemate, conventional carboxylic acid hydrogen bonding as cyclical (O-H...O=C)? [graph set R?²(8)] is present, with Oalkyl-H...O=Ci...

Gallagher, John F.; Brady, Fiona; Murphy, Carol

2000-01-01

140

Carbon dioxide hydrate phase equilibrium and cage occupancy calculations using ab initio intermolecular potentials.  

Science.gov (United States)

Gas hydrate deposits are receiving increased attention as potential locations for CO2 sequestration, with CO2 replacing the methane that is recovered as an energy source. In this scenario, it is very important to correctly characterize the cage occupancies of CO2 to correctly assess the sequestration potential as well as the methane recoverability. In order to predict accurate cage occupancies, the guest–host interaction potential must be represented properly. Earlier, these potential parameters were obtained by fitting to experimental equilibrium data and these fitted parameters do not match with those obtained by second virial coefficient or gas viscosity data. Ab initio quantum mechanical calculations provide an independent means to directly obtain accurate intermolecular potentials. A potential energy surface (PES) between H2O and CO2 was computed at the MP2/aug-cc-pVTZ level and corrected for basis set superposition error (BSSE), an error caused due to the lower basis set, by using the half counterpoise method. Intermolecular potentials were obtained by fitting Exponential-6 and Lennard-Jones 6-12 models to the ab initio PES, correcting for many-body interactions. We denoted this model as the “VAS” model. Reference parameters for structure I carbon dioxide hydrate were calculated using the VAS model (site–site ab initio intermolecular potentials) as ??(w)(0) = 1206 ± 2 J/mol and ?H(w)(0) = 1260 ± 12 J/mol. With these reference parameters and the VAS model, pure CO2 hydrate equilibrium pressure was predicted with an average absolute deviation of less than 3.2% from the experimental data. Predictions of the small cage occupancy ranged from 32 to 51%, and the large cage is more than 98% occupied. The intermolecular potentials were also tested by calculating the pure CO2 density and diffusion of CO2 in water using molecular dynamics simulations. PMID:24328234

Velaga, Srinath C; Anderson, Brian J

2014-01-16

 
 
 
 
141

The retinitis pigmentosa 28 protein FAM161A is a novel ciliary protein involved in intermolecular protein interaction and microtubule association.  

Science.gov (United States)

Loss-of-function mutations in the gene encoding FAM161A were recently discovered as the cause for RP28, an autosomal recessive form of retinitis pigmentosa. To initiate the characterization of the cellular role of FAM161A in the retina, we focused on its subcellular localization and conducted in vitro studies to identify FAM161A-interacting proteins and associated cellular structures. Immunohistochemistry revealed the presence of mouse FAM161A in the photoreceptor inner segments, the synaptic regions of the outer and inner plexiform layers and the ganglion cells. In mouse and human retinal sections from unfixed eyes, FAM161A localized to the ciliary region linking photoreceptor outer and inner segments. High-resolution immunofluorescence and immunoelectron microscopy mapped FAM161A to the connecting cilium, the basal body region and the adjacent centriole. Ectopic FAM161A was found in the centrosome and concentrated at the base of primary cilia in cultured cells. In addition, overexpressed FAM161A was clearly associated with microtubules during interphase and mitosis. The presence of FAM161A increased microtubule acetylation and stabilization. We further show that the evolutionarily conserved UPF0564 domain of FAM161A is crucial for its binding to microtubules and mediates homo- and heterotypic FAM161A and FAM161B interaction. In conclusion, our study shows that FAM161A is a microtubule-associated ciliary protein presumably involved in microtubule stabilization to maintain the microtubule tracks and/or in transport processes along microtubules in photoreceptors and other retinal cell types. PMID:22791751

Zach, Frank; Grassmann, Felix; Langmann, Thomas; Sorusch, Nasrin; Wolfrum, Uwe; Stöhr, Heidi

2012-11-01

142

Molecular near-field antenna effect in resonance hyper-Raman scattering: Intermolecular vibronic intensity borrowing of solvent from solute through dipole-dipole and dipole-quadrupole interactions.  

Science.gov (United States)

We quantitatively interpret the recently discovered intriguing phenomenon related to resonance Hyper-Raman (HR) scattering. In resonance HR spectra of all-trans-?-carotene (?-carotene) in solution, vibrations of proximate solvent molecules are observed concomitantly with the solute ?-carotene HR bands. It has been shown that these solvent bands are subject to marked intensity enhancements by more than 5 orders of magnitude under the presence of ?-carotene. We have called this phenomenon the molecular-near field effect. Resonance HR spectra of ?-carotene in benzene, deuterated benzene, cyclohexane, and deuterated cyclohexane have been measured precisely for a quantitative analysis of this effect. The assignments of the observed peaks are made by referring to the infrared, Raman, and HR spectra of neat solvents. It has been revealed that infrared active and some Raman active vibrations are active in the HR molecular near-field effect. The observed spectra in the form of difference spectra (between benzene/deuterated benzene and cyclohexane/deuterated cyclohexane) are quantitatively analyzed on the basis of the extended vibronic theory of resonance HR scattering. The theory incorporates the coupling of excited electronic states of ?-carotene with the vibrations of a proximate solvent molecule through solute-solvent dipole-dipole and dipole-quadrupole interactions. It is shown that the infrared active modes arise from the dipole-dipole interaction, whereas Raman active modes from the dipole-quadrupole interaction. It is also shown that vibrations that give strongly polarized Raman bands are weak in the HR molecular near-field effect. The observed solvent HR spectra are simulated with the help of quantum chemical calculations for various orientations and distances of a solvent molecule with respect to the solute. The observed spectra are best simulated with random orientations of the solvent molecule at an intermolecular distance of 10 Å. PMID:24880300

Shimada, Rintaro; Hamaguchi, Hiro-O

2014-05-28

143

Molecular near-field antenna effect in resonance hyper-Raman scattering: Intermolecular vibronic intensity borrowing of solvent from solute through dipole-dipole and dipole-quadrupole interactions  

Science.gov (United States)

We quantitatively interpret the recently discovered intriguing phenomenon related to resonance Hyper-Raman (HR) scattering. In resonance HR spectra of all-trans-?-carotene (?-carotene) in solution, vibrations of proximate solvent molecules are observed concomitantly with the solute ?-carotene HR bands. It has been shown that these solvent bands are subject to marked intensity enhancements by more than 5 orders of magnitude under the presence of ?-carotene. We have called this phenomenon the molecular-near field effect. Resonance HR spectra of ?-carotene in benzene, deuterated benzene, cyclohexane, and deuterated cyclohexane have been measured precisely for a quantitative analysis of this effect. The assignments of the observed peaks are made by referring to the infrared, Raman, and HR spectra of neat solvents. It has been revealed that infrared active and some Raman active vibrations are active in the HR molecular near-field effect. The observed spectra in the form of difference spectra (between benzene/deuterated benzene and cyclohexane/deuterated cyclohexane) are quantitatively analyzed on the basis of the extended vibronic theory of resonance HR scattering. The theory incorporates the coupling of excited electronic states of ?-carotene with the vibrations of a proximate solvent molecule through solute-solvent dipole-dipole and dipole-quadrupole interactions. It is shown that the infrared active modes arise from the dipole-dipole interaction, whereas Raman active modes from the dipole-quadrupole interaction. It is also shown that vibrations that give strongly polarized Raman bands are weak in the HR molecular near-field effect. The observed solvent HR spectra are simulated with the help of quantum chemical calculations for various orientations and distances of a solvent molecule with respect to the solute. The observed spectra are best simulated with random orientations of the solvent molecule at an intermolecular distance of 10 Å.

Shimada, Rintaro; Hamaguchi, Hiro-o.

2014-05-01

144

Liquid Crystal Modeling:. Electrostatic and Van Der Waals Interaction Energies for Molecular Building Blocks from Benzene to Cholesterol  

Science.gov (United States)

Intermolecular interaction energies for molecular dimers of benzene, indene, naphthalene, phenanthrene, cholesterol and glycyrrhetinic acid have been calculated according to the CVFF empirical force field of the DISCOVER program. The parallel orientations (side by-side) turned out to be the energetically most favourable ones, in agreement with the parametrization of Gay-Berne potentials. The energies of the T-shape and in-plane (end-to-end) orientations of the entirely asymmetric molecules cholesterol and glycyrrhetinic acid depend strongly on the actual atomic positions. This shows the extent to which the shape and charges of molecules determine all possible orientations and interaction energies in molecular ensembles.

Braun, Belinda; Hohla, Manfred; Köhler, Jutta

145

Metal-Arene Complexes with Indolo[3,2-c]-quinolines: Effects of Ruthenium vs Osmium and Modifications of the Lactam Unit on Intermolecular Interactions, Anticancer Activity, Cell Cycle, and Cellular Accumulation.  

Science.gov (United States)

Six novel ruthenium(II)- and osmium(II)-arene complexes with three modified indolo[3,2-c]quinolines have been synthesized in situ starting from 2-aminoindoloquinolines and 2-pyridinecarboxaldehyde in the presence of [M(p-cymene)Cl(2)](2) (M = Ru, Os) in ethanol. All complexes have been characterized by elemental analysis, spectroscopic techniques ((1)H, (13)C NMR, IR, UV-vis), and ESI mass spectrometry, while four complexes were investigated by X-ray diffraction. The complexes have been tested for antiproliferative activity in vitro in A549 (non-small cell lung), SW480 (colon), and CH1 (ovarian) human cancer cell lines and showed IC(50) values between 1.3 and >80 ?M. The effects of Ru vs Os and modifications of the lactam unit on intermolecular interactions, antiproliferative activity, and cell cycle are reported. One ruthenium complex and its osmium analogue have been studied for anticancer activity in vivo applied both intraperitoneally and orally against the murine colon carcinoma model CT-26. Interestingly, the osmium(II) complex displayed significant growth-inhibitory activity in contrast to its ruthenium counterpart, providing stimuli for further investigation of this class of compounds as potential antitumor drugs. PMID:23431223

Filak, Lukas K; Göschl, Simone; Heffeter, Petra; Ghannadzadeh Samper, Katia; Egger, Alexander E; Jakupec, Michael A; Keppler, Bernhard K; Berger, Walter; Arion, Vladimir B

2013-02-11

146

Structural modeling and intermolecular correlation of liquid chlorine dioxide  

International Nuclear Information System (INIS)

Chlorine dioxide (ClO2) is water-soluble yellow gas at room temperature. It has long been used as a disinfectant of tap water and various commodities owing to its strong oxidizing activity against various microbial proteins. The oxidizing activity is believed to be due to the presence of unpaired electron in its molecular orbital. Despite wealth of physicochemical studies of gaseous ClO2, little is known about liquid ClO2, especially about fine molecular structure and intermolecular interactions of liquid ClO2. The purpose of this study is to elucidate the fine structure and intermolecular orientations of ClO2 molecules in its liquid state using a high-energy X-ray diffraction technique. The measurements of liquid ClO2 were carried out at -50 to 0 degree Celsius using a two-axis diffractometer installed at the BL04B2 beamline in the third-generation synchrotron radiation facility SPring-8 (Hyogo, Japan). The incident X-ray beamline was 113.4 keV in energy and 0.1093 Armstrong in wavelength from a Si(111) monochromator with the third harmonic reflection. Liquid ClO2 held in a quartz capillary tube was placed in a temperature-controlled vacuum chamber. We obtained a structure factor S(Q) to a range of Q = 0.3-30 Amstrong-1 and a pair distribution function g(r) upon Fourier transform of the S(Q). The total g(r) showed peaks at 1.46, 2.08, 2.48, 3.16 and 4.24 Armstrong. From intramolecular bond lengths of 1.46 Armstrong for Cl-O and 2.48 Armstrong for O-O, O-Cl-O bond angle was estimated to be 116.1 degrees. Peaks at 3.16 and 4.24 Armstrong in the total g(r) strongly indicate presence of specific intermolecular orientations of ClO2 molecules that are distinct from those observed as a dimer in the solid phase ClO2. This view was further supported by molecular simulation using a reverse Monte Carlo method (RMC). (author)

2009-07-01

147

Neutral CH3Cl and CH3Br clusters studied by X-ray photoelectron spectroscopy and modeling: Insight to intermolecular interactions and structure  

International Nuclear Information System (INIS)

Single-component clusters of methyl chloride and methyl bromide have been produced by adiabatic expansion and their C 1s, Cl 2p and Br 3d photoelectron spectra recorded using synchrotron radiation and a high-resolution electron analyzer. The experimentally observed cluster-to-monomer shifts in core-level ionization energies are interpreted in terms of theoretical models based on molecular dynamics (MD) in conjunction with polarizable force fields developed and validated in the course of this work. MD simulations have also been used to explore the global and local structure of the clusters, providing evidence for a predominance of anti-parallel, head-to-tail arrangement of neighboring molecules. Whereas the cluster-to-monomer shifts are strongly dominated by polarization effects, the polarization contribution is very similar for ionization of carbon and the halogen, respectively. The difference in cluster shifts between the two ionization sites within the same molecule, C vs. Cl or C vs. Br, is thus determined by permanent electrostatic moments, i.e. the magnitude and direction of the permanent dipole moment and the local alignment of dipoles

2008-11-01

148

Energy of interaction between solid surfaces and liquids  

CERN Multimedia

We consider the wetting transition on a planar surface in contact with a semi-infinite fluid. In the classical approach, the surface is assumed to be solid, and when interaction between solid and fluid is sufficiently short-range, the contribution of the fluid can be represented by a surface free energy with a density of the form Phi(rho_s), where rho_s is the limiting density of the fluid at the surface. In the present paper we propose a more precise representation of the surface energy that takes into account not only the value of rho_s but also the contribution from the whole density profile rho(z) of the fluid, where z is the coordinate normal to the surface. The specific value of the functional of rho_s at the surface is expressed in mean-field approximation through the potentials of intermolecular interaction and some other parameters of the fluid and the solid wall. An extension to the case of fluid mixtures in contact with a solid surface is proposed.

Gouin, Henri

2008-01-01

149

Weak interactions at high energies  

International Nuclear Information System (INIS)

Review lectures are presented on the phenomenological implications of the modern spontaneously broken gauge theories of the weak and electromagnetic interactions, and some observations are made about which high energy experiments probe what aspects of gauge theories. Basic quantum chromodynamics phenomenology is covered including momentum dependent effective quark distributions, the transverse momentum cutoff, search for gluons as sources of hadron jets, the status and prospects for the spectroscopy of fundamental fermions and how fermions may be used to probe aspects of the weak and electromagnetic gauge theory, studies of intermediate vector bosons, and miscellaneous possibilities suggested by gauge theories from the Higgs bosons to speculations about proton decay. 187 references

1978-01-01

150

Topological characterisation of intermolecular lithium bonding  

International Nuclear Information System (INIS)

Bader's atoms in molecules topological theory was employed to analyse the B3LYP/6-311++G(3d2f,3p2d) electron distributions of several adducts that contain LiF. The results indicate significant differences between lithium bonding (LB) and hydrogen bonding (HB): (i) in spite of their larger stability, the charge density at the intermolecular critical points of LB complexes is about half of its value in the corresponding HB complexes, suggesting a dominant role of electrostatic interactions in the former; (ii) the Li atom in LB compounds is more shared between the base atom and the attached fluorine than hydrogen in HB complexes; and (iii) the Li atom gains electron charge from the hydrogens in all the complexes here studied, undergoing energetic stabilisation

2006-08-01

151

Topological characterisation of intermolecular lithium bonding  

Energy Technology Data Exchange (ETDEWEB)

Bader's atoms in molecules topological theory was employed to analyse the B3LYP/6-311++G(3d2f,3p2d) electron distributions of several adducts that contain LiF. The results indicate significant differences between lithium bonding (LB) and hydrogen bonding (HB): (i) in spite of their larger stability, the charge density at the intermolecular critical points of LB complexes is about half of its value in the corresponding HB complexes, suggesting a dominant role of electrostatic interactions in the former; (ii) the Li atom in LB compounds is more shared between the base atom and the attached fluorine than hydrogen in HB complexes; and (iii) the Li atom gains electron charge from the hydrogens in all the complexes here studied, undergoing energetic stabilisation.

Vila, Antonio [Departamento de Quimica Fisica, Universidade de Vigo, Lagoas-Marcosende, 36310-Vigo, Galicia (Spain); Vila, Esther [Departamento de Quimica Fisica, Universidade de Vigo, Lagoas-Marcosende, 36310-Vigo, Galicia (Spain); Mosquera, Ricardo A. [Departamento de Quimica Fisica, Universidade de Vigo, Lagoas-Marcosende, 36310-Vigo, Galicia (Spain)], E-mail: mosquera@uvigo.es

2006-08-01

152

High-Energy Neutrino Interactions  

CERN Multimedia

This experiment studies neutrino interactions in iron at the highest available energies using the narrow-band neutrino beam N3 and the wide-band neutrino beam N1. The basis of the detector is a massive target-calorimeter in which the energy deposited by a neutrino (or antineutrino) is measured by electronic techniques and the momentum of outgoing muons is determined by magnetic deflection. The detector is constructed in the form of a 20 m long iron-cored toroidal magnet, composed of modules of length 70~cm and 90~cm, and of 3.75~m diameter. Drift chambers placed in between each module measure the trajectory of muons from the neutrino interactions. The modules are of three types. The first ten modules are constructed of 2.5~cm iron plates with 20~scintillator planes inserted between the plates. The next five modules are constructed of 5~cm plates with 15~planes of scintillator and the last six modules are constructed of 15~cm plates with 5~planes of scintillators. The total mass of the detector is @=~1400 tons...

2002-01-01

153

Intermolecular interactions: basis set and intramolecular correlation effects on semiempirical methods. Application to (C[sub 2]H[sub 2])[sub 2], (C[sub 2]H[sub 2])[sub 3] and (C[sub 2]H[sub 4])[sub 2  

Energy Technology Data Exchange (ETDEWEB)

A detailed study of the intrinsic consistency of the semiempirical method of P. Claverie namely, the effects of the basis set and intramolecular correlation on the multipole distributions of molecular subunits and the influence of the electronic population of each atom in the molecular subunit on its van der Waals radius, is performed on some van der Waals dimers. The validity, limits of this model and the appropriate way to use it is established. In particular, the dependence of the geometry and the interaction energy on the basis set chosen and the intramolecular correlation shows that the multipole distribution involved in the calculation of the electrostatic and polarization terms must be derived from a correlated wave function within an extended basis set. Associated to non local methods for finding stationary points, the method of P. Claverie reproduce reliably the intermolecular geometrical parameters observed for the equilibrium structures and the transition states of the dimer and trimer of acetylene. In addition, a study of the equilibrium structures of the ethylene dimer is presented, the aim of being to clarify the considerable uncertainty in their number and their geometry. (orig.)

Brenner, V. (CEA-CE Saclay, DSM/DRECAM/SPAM, 91 Gif sur Yvette (France)); Millie, P. (CEA-CE Saclay, DSM/DRECAM/SPAM, 91 Gif sur Yvette (France))

1994-07-01

154

Spin radical enhanced magnetocapacitance effect in intermolecular excited states.  

Science.gov (United States)

This article reports the magnetocapacitance effect (MFC) based on both pristine polymer MEH-PPV and its composite system doped with spin radicals (6R-BDTSCSB). We observed that a photoexcitation leads to a significant positive MFC in the pristine MEH-PPV. Moreover, we found that a low doping of spin radicals in polymer MEH-PPV causes a significant change on the MFC signal: an amplitude increase and a line-shape narrowing under light illumination at room temperature. However, no MFC signal was observed under dark conditions in either the pristine MEH-PPV or the radical-doped MEH-PPV. Furthermore, the magnitude increase and line-shape narrowing caused by the doped spin radicals are very similar to the phenomena induced by increasing the photoexcitation intensity. Our studies suggest that the MFC is essentially originated from the intermolecular excited states, namely, intermolecular electron-hole pairs, generated by a photoexcitation in the MEH-PPV. More importantly, by comparing the effects of spin radicals and electrically polar molecules on the MFC magnitude and line shape, we concluded that the doped spin radicals can have the spin interaction with intermolecular excited states and consequently affect the internal spin-exchange interaction within intermolecular excited states in the development of MFC. Clearly, our experimental results indicate that dispersing spin radicals forms a convenient method to enhance the magnetocapacitance effect in organic semiconducting materials. PMID:24144347

Zang, Huidong; Wang, Jianguo; Li, Mingxing; He, Lei; Liu, Zitong; Zhang, Deqing; Hu, Bin

2013-11-14

155

Free energy decomposition analysis of bonding and nonbonding interactions in solution  

Science.gov (United States)

A free energy decomposition analysis algorithm for bonding and nonbonding interactions in various solvated environments, named energy decomposition analysis-polarizable continuum model (EDA-PCM), is implemented based on the localized molecular orbital-energy decomposition analysis (LMO-EDA) method, which is recently developed for interaction analysis in gas phase [P. F. Su and H. Li, J. Chem. Phys. 130, 074109 (2009)]. For single determinant wave functions, the EDA-PCM method divides the interaction energy into electrostatic, exchange, repulsion, polarization, desolvation, and dispersion terms. In the EDA-PCM scheme, the homogeneous solvated environment can be treated by the integral equation formulation of PCM (IEFPCM) or conductor-like polarizable continuum model (CPCM) method, while the heterogeneous solvated environment is handled by the Het-CPCM method. The EDA-PCM is able to obtain physically meaningful interaction analysis in different dielectric environments along the whole potential energy surfaces. Test calculations by MP2 and DFT functionals with homogeneous and heterogeneous solvation, involving hydrogen bonding, vdW interaction, metal-ligand binding, cation-?, and ionic interaction, show the robustness and adaptability of the EDA-PCM method. The computational results stress the importance of solvation effects to the intermolecular interactions in solvated environments.

Su, Peifeng; Liu, Hui; Wu, Wei

2012-07-01

156

A unified treatment of high energy interactions  

Energy Technology Data Exchange (ETDEWEB)

It is well known that high energy interactions as different as electron-positron annihilation, deep inelastic lepton-nucleon scattering, proton-proton interactions, and nucleus-nucleus collisions have many features in common. Based upon this observation, a model for all these interactions is constructed which relies on the fundamental hypothesis that the behavior of high energy interactions is universal. (author) 19 refs.

Drescher, H.J.; Werner, K. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees; Hladik, M. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees]|[SAP AG, Berlin (Germany); Ostapchenko, S. [Moscow State Univ. (Russian Federation). Inst. of Nuclear Physics]|[Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Physique Subatomique et des Technologies Associees

1999-11-01

157

Desensitization and recovery of metastable intermolecular composites  

Energy Technology Data Exchange (ETDEWEB)

A method to substantially desensitize a metastable intermolecular composite material to electrostatic discharge and friction comprising mixing the composite material with an organic diluent and removing enough organic diluent from the mixture to form a mixture with a substantially putty-like consistency, as well as a concomitant method of recovering the metastable intermolecular composite material.

Busse, James R. (South Fork, CO); Dye, Robert C. (Los Alamos, NM); Foley, Timothy J. (Los Alamos, NM); Higa, Kelvin T. (Ridgecrest, CA); Jorgensen, Betty S. (Jemez Springs, NM); Sanders, Victor E. (White Rock, NM); Son, Steven F. (Los Alamos, NM)

2010-09-07

158

Predicting lattice energy and structure of molecular crystals by first-principles method: Role of dispersive interactions  

Science.gov (United States)

The accurate calculation of lattice energy and structure of molecular crystals represent a test of the ability of first-principles periodic density functional method to model the relatively weak intermolecular interactions found in molecular crystals. The weak intermolecular dispersion interactions need to be considered for the accurate prediction of crystal structure and lattice energy of molecular crystals. In this paper, we report the calculation of lattice energies and structure of a set of eight molecular crystals at the ab initio level of theory. Hartree-Fock and density functional theory with and without dispersion correction potential were employed. Our results clearly show with application of triple zeta polarization (TZP) basis set, the lattice parameters obtained using B3LYP functional with dispersion interactions give better agreement with the experimental results. On the other hand, the lattice energies obtained using B3LYP-D/TZP method is severely underestimated. The lattice energies calculated at B3LYP-D/6-31G(d,p) level of theory are in close agreement with the corresponding experimental results because of smaller size of basis sets provide large basis set superposition errors which compensate the missing dispersion energies.

Singh, M. K.

2014-06-01

159

Study of Coulomb interactions at VECC energies  

CERN Document Server

we study the effect of Coulomb interactions on balance energy for various colliding nuclei in terms of mass asymmetry. This study shows that the balance energy is affected by the Coulomb interactions as well as different nuclear equations of state. The preliminary results calculated theoretically will be of great use for scientists at VECC. This study is further in progress.

Kaur, Varinderjit; Puri, Rajeev K; Bhattacharya, S

2011-01-01

160

Propagation studies of metastable intermolecular composites (MIC).  

Energy Technology Data Exchange (ETDEWEB)

Thermite materials are attractive energetic materials because the reactions are highly exothermic, have high energy densities, and high temperatures of combustion. However, the application of thermite materials has been limited because of the relative slow release of energy compared to other energetic materials. Engineered nano-scale composite energetic materials, such as Al/MoO{sub 3}, show promise for additional energetic material applications because they can react very rapidly. The composite material studied in this work consists of tailored, ultra-fine grain (30-200 nm diameter) aluminum particles that dramatically increase energy release rates of these thermite materials. These reactant clusters of fuel and oxidizer particles are in nearly atomic scale proximity to each other but are constrained from reaction until triggered. Despite the growing importance of nano-scale energetic materials, even the most basic combustion characteristics of these materials have not been thoroughly studied. This paper reports initial studies of the ignition and combustion of metastable intermolecular composites (MIC) materials. The goals were lo obtain an improved understanding of flame propagation mechanisms and combustion behaviors associated with nano-structured energetic materials. Information on issues such as reaction rate and behavior as a function of composition (mixture ratio), initial static charge, and particle size are essential and will allow scientists to design applications incorporating the benefits of these compounds. The materials have been characterized, specifically focusing on particle size, shape, distribution and morphology.

Son, S. F. (Steven F.); Busse, J. R. (James R.); Asay, B. W. (Blaine W.); Peterson, P. D. (Paul D.); Mang, J. T. (Joseph T.); Bockmon, B. (Bryan); Pantoya, M. (Michelle)

2002-01-01

 
 
 
 
161

Simple non-empirical procedure for spin-component-scaled MP2 methods applied to the calculation of dissociation energy curve of noncovalently-interacting systems  

CERN Document Server

We present a simple and non-empirical method to determine optimal scaling coefficients, within the (spin-component)-scaled MP2 approach, for calculating intermolecular potential energies of noncovalently-interacting systems. The method is based on an observed proportionality between (spin-component) MP2 and CCSD(T) energies for a wide range of intermolecular distances and allows to compute with high accuracy a large portion of the dissociation curve at the cost of a single CCSD(T) calculation. The accuracy of the present procedure is assessed for a series of noncovalently-interacting test systems: the obtained results reproduce CCSD(T) quality in all cases and definitely outperform conventional MP2, CCSD and SCS-MP2 results. The difficult case of the Beryllium dimer is also considered.

Grabowski, I; Della Sala, F

2013-01-01

162

A simple non-empirical procedure for spin-component-scaled MP2 methods applied to the calculation of the dissociation energy curve of noncovalently-interacting systems.  

Science.gov (United States)

We present a simple and non-empirical method to determine optimal scaling coefficients, within the (spin-component)-scaled MP2 approach, for calculating intermolecular potential energies of noncovalently-interacting systems. The method is based on an observed proportionality between (spin-component) MP2 and CCSD(T) energies for a wide range of intermolecular distances and allows us to compute with high accuracy a large portion of the dissociation curve at the cost of a single CCSD(T) calculation. The accuracy of the present procedure is assessed for a series of noncovalently-interacting test systems: the obtained results reproduce CCSD(T) quality in all cases and definitely outperform conventional MP2, CCSD and SCS-MP2 results. The difficult case of the beryllium dimer is also considered. PMID:23942763

Grabowski, Ireneusz; Fabiano, Eduardo; Della Sala, Fabio

2013-10-01

163

Ferroelastic and ferroelectric phase transition in a molecular crystal : tanane - 3. — From ab initio computation of the intermolecular forces to statistical mechanics of the transition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

On the basis of structural data of the disordered tetragonal phase of tanane, the Van der Waals intermolecular forces are computed for the 16 nearest neighbours of a given molecule. Considering first the molecular ordering in a « rigid » tetragonal lattice, the pair energies between neighbouring molecules are analysed within a pseudo-spin formalism which shows that the main ordering interactions define linear chains of molecules along the ferroelectric Z-axis. As there is no exact procedure...

Legrand, J. F.; Lajzerowicz, J.; Lajzerowicz-bonneteau, J.; Capiomont, A.

1982-01-01

164

The inclusion of electron correlation in intermolecular potentials: Applications to the formamide dimer and liquid formamide  

DEFF Research Database (Denmark)

A test of the quality of the electrostatic properties and polarizabilities used in the nonempirical molecular orbital (NEMO) potential is carried out for formamide by calculating the molecular dipole moment and polarizability at the second-order Moller-Plesset (MP2) level of theory. The molecular dipole moment is 11% lower at the MP2 level than at the Hartree-Fock (HF) level, whereas the isotropic part of the polarizability is increased by 36% by adding electron correlation and using a considerably larger basis set. The atomic charges, dipole moments and polarizabilities obtained at the HF level are rescaled to get the correct molecular properties at the MP2 level. The potential minimum for the cyclic dimer of formamide is -17.50 kcal/mol with the MP2-scaled properties and is significantly lower than other potentials give. Two intermolecular potentials are constructed and used in subsequent molecular dynamics simulations: one with the regular NEMO potential and the other with the rescaled MP2 properties. A damping of the electrostatic field at short intermolecular distances is included in the present NEMO model. The average energies for liquid formamide are lower for the MP2-scaled model and are in good agreement with experimental results. The lowering of the simulation energy for the MP2-scaled potential indicates the strong dispersive interactions in liquid formamide.

Brdarski, S.; Ã?strand, P.-O.

2000-01-01

165

Low energy K N interactions  

International Nuclear Information System (INIS)

Chiral SU(3) effective field theory in combination with a relativistic coupled-channels approach is used to perform a novel analysis of the strong interaction shift and width in kaonic hydrogen in view of the new accurate DEAR measurements. Questions of consistency with previous K-p data are examined. Coulomb and isospin breaking effects are shown to be important. (author)

2005-01-01

166

Pion nucleon interaction at low energy  

International Nuclear Information System (INIS)

A theory of the ?N interaction at low energy is described. An analogy is made with an unusual approach to potential scattering theory. Phase shifts, cross sections, and scattering amplitudes and lengths are calculated. 28 references

1979-03-09

167

Interacting Ricci-like holographic dark energy  

Science.gov (United States)

In a flat Friedmann-Lemaitre-Robertson-Walker background, a scheme of dark matter-dark energy interaction is studied considering a holographic Ricci-like model for the dark energy. Without giving a priori some specific model for the interaction function, we show that this function can experience a change of sign during the cosmic evolution. The parameters involved in the holographic model are adjusted with Supernova data and we obtained results compatible with the observable universe.

Arévalo, F.; Cifuentes, P.; Lepe, Samuel; Peña, Francisco

2014-05-01

168

Vacuum energies and multipole interactions  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In this paper, we present a quantum-field-theoretical description of the interaction between stationary and localized external sources linearly coupled to bosonic fields (specifically, we study models with a scalar and the Maxwell field). We consider external sources that simulate not only point cha [...] rges but also higher-multipole distributions along D-dimensional branes. Our results complement the ones previously obtained in reference [1].

Barone, F.A.; Flores-Hidalgo, G..

169

Model-free nuclear magnetic resonance study of intermolecular free energy landscapes in liquids with paramagnetic Ln3+ spotlights: Theory and application to Arg-Gly-Asp  

Science.gov (United States)

We propose an easily applicable method for investigating the pair distribution function of a lanthanide Ln3+ complex LnL (L = ligand) with respect to any solvent or solute molecule A carrying observable nuclear spins. Let r be the distance of Ln3+ to the observed nuclear spin I. We derive a simple expression of the experimental value of the configurational average of 1/r6 in terms of longitudinal paramagnetic relaxation (rate) enhancements (PREs) of the spin I measured on a standard high-resolution NMR spectrometer and due to well-chosen concentrations of LnL complexes in which Ln3+ is a fast-relaxing paramagnetic lanthanide or the slowly-relaxing gadolinium Gd3+. The derivation is justified in the general case of a molecule A which is by turns in a bound state where it follows the complex and a free state where it moves independently. It rests on the expression of the underlying PRE theory in terms of the angle-dependent pair distribution function of LnL and A. The simplifications of this theory in the high-field regime and under the condition of fast exchange between bound and free states are carefully discussed. We also show that original information on the angle dependence of the molecular pair distribution function can be gained from the measured paramagnetic dipolar shifts induced by complexed fast-relaxing Ln3+ ions. The method is illustrated by the case study of the anionic Lnttha3- = [Ln3+(ttha)]3- (ttha6- = triethylene tetraamine hexacetate) complex interacting with the biologically important tripeptide Arg-Gly-Asp (RGD) which carries peripheral ionic groups. The usefulness of an auxiliary reference outer sphere probe solute is emphasized.

Fries, Pascal H.

2012-01-01

170

Expectations for ultra-high energy interactions  

International Nuclear Information System (INIS)

Strong interactions at ultra-high energies are discussed with emphasis on the hadrons produced in high energy collisions. Evidence is considered that quantum chromodynamics might be the right theory, and also some estimates are given of quantum chromodynamics asymptotic-freedom phenomena, the work under discussion being very preliminary. 6 references

1978-03-31

171

Inclusive ?++ in pp interactions at ISR energies  

International Nuclear Information System (INIS)

Inclusive cross sections for ?++ production in pp interactions at different ISR energies are presented. The differential cross section dsigma/dx for ?++ production is found to be approximately independent of Feynman x. No strong energy dependence is seen over the ISR energy range. The topological cross sections of ?++ at ?s=62 GeV show an appreciable contribution from non-diffractive production mechanisms. An upper limit for the ?0 production cross section is determined. (orig.)

1984-01-01

172

Tachyon Reconstruction of Interacting Ghost Dark Energy  

CERN Document Server

Recently it has been argued that a possible source for the dark energy may arise due to the contribution to the vacuum energy of the QCD ghost in a time-dependent background. In this paper we establish a connection between interacting ghost dark energy and tachyon field. It is demonstrated that the evolution of the ghost dark energy dominated universe can be described completely by a single tachyon scalar field. The potential and the dynamics of the tachyon field are reconstructed according to the evolutionary behavior of ghost energy density.

Sheykhi, A; Ebrahimi, E

2011-01-01

173

Determination of intermolecular transfer integrals from DFT calculations  

Energy Technology Data Exchange (ETDEWEB)

Theoretical studies of charge transport in organic conducting systems pose a unique challenge since they require multiscale schemes that combine quantum-chemical, molecular dynamics and kinetic Monte-Carlo calculations. The description of the mobility of electrons and holes in the hopping regime relies on the determination of intermolecular hopping rates in large scale morphologies. Using Marcus theory these rates can be calculated from intermolecular transfer integrals and on-site energies. Here we present a detailed computational study on the accuracy and efficiency of density-functional theory based approaches to the determination of intermolecular transfer integrals. First, it is demonstrated how these can be obtained from quantum-chemistry calculations by forming the expectation value of a dimer Fock operator with frontier orbitals of two neighboring monomers based on a projective approach. We then consider the prototypical example of one pair out of a larger morphology of Tris(8-hydroxyquinolinato)aluminium (Alq3) and study the influence of computational parameters, e.g. the choice of basis sets, exchange-correlation functional, and convergence criteria, on the calculated transfer integrals. The respective accuracies and efficiencies are compared in order to derive an optimal strategy for future simulations based on the full morphology.

Baumeier, Bjoern; Andrienko, Denis [Max-Planck Institute for Polymer Research, Mainz (Germany)

2010-07-01

174

The water/graphitic-carbon interaction energy  

Science.gov (United States)

The water/graphitic-carbon interaction energy was obtained for a sample having a water surface site adsorption density of 13.3 ?mol m -2. The interaction energy was determined from the spreading pressure of water, its surface tension and the water contact angle and using a formula obtained by the combination of the Young equation with a general equation of pair interaction. The values obtained for contact angles 42° and 86° are 7.63 and 7.18 kJ mol -1 of water are similar to the water binding energies obtained from molecular dynamic simulations of water droplets on a graphite surface: 6.7-8.33 kJ mol -1.

Helmy, Ahmed K.; Ferreiro, Eladio A.; de Bussetti, Silvia G.

2007-03-01

175

Catalytic intermolecular alkene oxyamination with nitrenes.  

Science.gov (United States)

The Rh(II) -catalyzed intermolecular addition of nitrenes to aromatic and aliphatic alkenes provides vicinal amino alcohols with yields of up to 95?% and complete regioselectivity. This 1,2-oxyamination reaction involves the formation of an aziridine intermediate that undergoes in situ ring opening. The latter is induced by the Rh-bound nitrene that behaves as a Lewis acid. PMID:24939636

Dequirez, Geoffroy; Ciesielski, Jennifer; Retailleau, Pascal; Dauban, Philippe

2014-07-14

176

A new ab initio interaction energy surface and high-resolution spectra of the H2-CO van der Waals complex  

Science.gov (United States)

A new four-dimensional intermolecular potential-energy surface for the H2-CO complex is presented. The ab initio points have been computed on a five-dimensional grid including the dependence on the H-H separation (the C-O separation was fixed). The surface has then been obtained by averaging over the intramolecular vibration of H2. The coupled-cluster supermolecular method with single, double, and noniterative triple excitations has been used to calculate the interaction energy. The correlation part of the interaction energy has been obtained from extrapolations based on calculations in a series of basis sets. An analytical fit of the ab initio potential-energy surface has the global minimum of -93.049 cm-1 at the intermolecular separation of 7.92 bohr for the linear geometry with the C atom pointing toward the H2 molecule. For the other linear geometry, with the O atom pointing toward H2, the local minimum of -72.741 cm-1 has been found for the intermolecular separation of 7.17 bohr. The potential has been used to calculate the rovibrational energy levels of the para-H2-CO complex. The results agree very well with those observed by McKellar [A. R. W. McKellar J. Chem. Phys. 108, 1811 (1998)]: the discrepancies are smaller than 0.1 cm-1. The calculated dissociation energy is equal to 19.527 cm-1 and significantly smaller than the value of 22 cm-1 estimated from the experiment. Predictions of rovibrational energy levels for ortho-H2-CO have also been done and can serve as a guidance to assign recorded experimental spectra. The interaction second virial coefficient has been calculated and compared with the experimental data.

Jankowski, Piotr; Szalewicz, Krzysztof

2005-09-01

177

Electroweak interactions and high-energy limit  

CERN Document Server

A pedagogical introduction to the equivalence theorem for longitudinal vector bosons in electroweak theories is given and the problem of tree-level unitarity at high energies in models of electroweak interactions is briefly reviewed. To make the treatment self-containded, the basic of the Standard Model are summarized in an appendix.

Horejsi, J

1996-01-01

178

Interacting vacuum energy in the dark sector  

CERN Document Server

We analyse three cosmological scenarios with interaction in the dark sector, which are particular cases of a general expression for the energy flux from vacuum to matter. In the first case the interaction leads to a transition from an unstable de Sitter phase to a radiation dominated universe, avoiding in this way the initial singularity. In the second case the interaction gives rise to an inflationary expansion without inflaton, with desired features of standard inflation. Finally, the third scenario is a concordance model for the late-time universe, with the vacuum term decaying into cold dark matter. We identify the physics behind these forms of interaction, and we show that they can be described as particular types of the modified Chaplygin gas.

Chimento, L P

2014-01-01

179

Binding energies of hypernuclei and hypernuclear interactions  

International Nuclear Information System (INIS)

In part 1 the effect of nuclear core dynamics on the binding energies of ? hypernuclei is discussed in the framework of variational correlated wave functions. In particular, the authors discuss a new rearrangement energy contribution and its effect on the core polarization. In part 2 they consider the interpretation of the ? single-particle energy in terms of basic ?-nuclear interactions using a local density approximation based on a Fermi hypernetted chain calculation of the A binding to nuclear matter. To account for the data strongly repulsive 3-body ?NN forces are required. Also in this framework they discuss core polarization for medium and heavier hypernuclei

1996-05-26

180

Constraining dark energy interacting models with WMAP  

CERN Document Server

We determine the range of parameter space of an interacting quintessence (IQ) model that best fits the luminosity distance of type Ia supernovae data and the recent WMAP measurements of Cosmic Microwave Background temperature anisotropies. Models in which quintessence decays into dark matter provide a clean explanation for the coincidence problem. We focus on cosmological models of zero spatial curvature. We show that if the dark energy (DE) decays into cold dark matter (CDM) at a rate that brings the ratio of matter to dark energy constant at late times, the supernovae data are not sufficient to constrain the interaction parameter. On the contrary, WMAP data constrain it to be smaller than $c^2 < 10^{-2}$ at the $3\\sigma$ level. Accurate measurements of the Hubble constant and the dark energy density, independent of the CMB data, would support/disprove this set of models.

Olivares, G; Pavón, D; Olivares, German; Atrio-Barandela, Fernando; Pavon, Diego

2006-01-01

 
 
 
 
181

Interactive Joint Transfer of Energy and Information  

DEFF Research Database (Denmark)

In some communication networks, such as passive RFID systems, the energy used to transfer information between a sender and a recipient can be reused for successive communication tasks. In fact, from known results in physics, any system that exchanges information via the transfer of given physical resources, such as radio waves, particles and qubits, can conceivably reuse, at least part, of the received resources. This paper aims at illustrating some of the new challenges that arise in the design of communication networks in which the signals exchanged by the nodes carry both information and energy. To this end, a baseline two-way communication system is considered in which two nodes communicate in an interactive fashion. In the system, a node can either send an â??onâ? symbol (or â??1â?), which costs one unit of energy, or an â??offâ? signal (or â??0â?), which does not require any energy expenditure. Upon reception of a â??1â? signal, the recipient node â??harvestsâ?, with some probability, the energy contained in the signal and stores it for future communication tasks. Inner and outer bounds on the achievable rates are derived. Numerical results demonstrate the effectiveness of the proposed strategies and illustrate some key design insights. Index Termsâ?? Two-way channel, interactive communication, energy transfer, energy harvesting.

Popovski, Petar; Fouladgar, A. M.

2013-01-01

182

Interacting boson model with energy density functionals  

International Nuclear Information System (INIS)

A brief overview of the recent advancement in the microscopic study of the interacting boson model (IBM) is given. A new nucleon-boson mapping method has been proposed recently, that derives the IBM Hamiltonian based on the self-consistent mean-field model with the microscopic energy density functional (EDF). The mean-field total energy surface computed with a given EDF is mapped onto the analogous energy expectation value in the boson condensate, thereby the energy spectrum and the transition rates are generated. Since the EDF framework allows an accurate global description of nuclear intrinsic properties, the IBM is derived in a unified way, basically for any situation of low-energy quadrupole collective states of nuclei. The basic notion of the new mapping technique is sketched

2013-07-03

183

Dilute Fermi gas: kinetic and interaction energies  

CERN Document Server

A dilute homogeneous 3D Fermi gas in the ground state is considered for the case of a repulsive pairwise interaction. The low-density (dilution) expansions for the kinetic and interaction energies of the system in question are calculated up to the third order in the dilution parameter. Similar to the recent results for a Bose gas, the calculated quantities turn out to depend on a pairwise interaction through the two characteristic lengths: the former, $a$, is the well-known s-wave scattering length, and the latter, $b$, is related to $a$ by $b=a-m (\\partial a/\\partial m)$, where $m$ stands for the fermion mass. To take control of the results, calculations are fulfilled in two independent ways. The first involves the Hellmann-Feynman theorem, taken in conjunction with a helpful variational theorem for the scattering length. This way is used to derive the kinetic and interaction energies from the familiar low-density expansion of the total system energy first found by Huang and Yang. The second way operates wit...

Shanenko, A A

2004-01-01

184

Polaron interaction energies in reduced tungsten trioxide  

International Nuclear Information System (INIS)

Consideration of the properties of reduced tungsten trioxide suggest that the mobile charge carriers are polarons. As it is uncertain how the presence of polarons will influence the microstructures of the crystallographic shear (CS) planes present in reduced tungsten trioxide we have calculated both the polaron-CS plane and polaron-polaron interaction energy for a variety of circumstances. Three CS plane geometries were considered, (102), (103), and (001) CS plane arrays, and the nominal compositions of the crystals ranged from WO270 to WO30. The polarons were assumed to have radii from 0.6 to 1.0 nm and the polaron-CS plane electrostatic interaction was assumed to be screened. The results suggest that for the most part the total interaction energy is small and is unlikely to be of major importance in controlling the microstructures found in CS planes. However, at very high polaron densities the interaction energy could be appreciable and may have some influence on the existence range of CS phases

1981-07-15

185

Spectroscopic studies on the intermolecular charge transfer interaction of Fe(II)- and Fe(III)-phthalocyanines with 2,3,5,6-tetrachloro-1,4-benzoquinone and its application in colorimetric sensing of amino acids and amines  

Science.gov (United States)

The interactions of Fe IIPc and Fe IIIPc with ?-acceptor 2,3,5,6-tetrachloro-1,4-benzoquinone ( p-chloranil, p-CHL) have been investigated spectroscopically (UV/vis and FT-IR) and spectrofluorimetrically at three different temperatures. The stoichiometry of the complexes was found to be 1:1. The results of electronic spectral studies indicated that the formation constant for Fe IIPc- p-CHL system is found to be higher than that for Fe IIIPc- p-CHL system. This observation is well supported by the results of fluorescence quenching studies and the association constants calculated for Fe IIPc- p-CHL system is 4.2 × 10 3 mol L -1 and that for Fe IIIPc- p-CHL system is 2.2 × 10 3 mol L -1. The data are discussed in terms of physico-chemical parameters viz. molar extinction coefficient, oscillator strength, dipole moment, ionization potential, dissociation energy and thermodynamic parameters. The results indicated that the formation of ?-? CT complex is spontaneous and endothermic. Preliminary studies indicated that the CT complex can effectively be used as a colorimetric agent for sensing amino acids and amines.

Balraj, Chellamuthu; Elango, Kuppanagounder P.

2012-02-01

186

Interactions between dark energy and dark matter  

Energy Technology Data Exchange (ETDEWEB)

We have investigated interacting dark energy cosmologies both concerning their impact on the background evolution of the Universe and their effects on cosmological structure growth. For the former aspect, we have developed a cosmological model featuring a matter species consisting of particles with a mass that increases with time. In such model the appearance of a Growing Matter component, which is negligible in early cosmology, dramatically slows down the evolution of the dark energy scalar field at a redshift around six, and triggers the onset of the accelerated expansion of the Universe, therefore addressing the Coincidence Problem. We propose to identify this Growing Matter component with cosmic neutrinos, in which case the present dark energy density can be related to the measured average mass of neutrinos. For the latter aspect, we have implemented the new physical features of interacting dark energy models into the cosmological N-body code GADGET-2, and we present the results of a series of high-resolution simulations for a simple realization of dark energy interaction. As a consequence of the new physics, cold dark matter and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of cold dark matter halos are less concentrated in coupled dark energy cosmologies compared with {lambda}{sub CDM}. Also, the baryon fraction in halos in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the {lambda}{sub CDM} model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter space of such scenarios. (orig.)

Baldi, Marco

2009-03-20

187

Interactions between dark energy and dark matter  

International Nuclear Information System (INIS)

We have investigated interacting dark energy cosmologies both concerning their impact on the background evolution of the Universe and their effects on cosmological structure growth. For the former aspect, we have developed a cosmological model featuring a matter species consisting of particles with a mass that increases with time. In such model the appearance of a Growing Matter component, which is negligible in early cosmology, dramatically slows down the evolution of the dark energy scalar field at a redshift around six, and triggers the onset of the accelerated expansion of the Universe, therefore addressing the Coincidence Problem. We propose to identify this Growing Matter component with cosmic neutrinos, in which case the present dark energy density can be related to the measured average mass of neutrinos. For the latter aspect, we have implemented the new physical features of interacting dark energy models into the cosmological N-body code GADGET-2, and we present the results of a series of high-resolution simulations for a simple realization of dark energy interaction. As a consequence of the new physics, cold dark matter and baryon distributions evolve differently both in the linear and in the non-linear regime of structure formation. Already on large scales, a linear bias develops between these two components, which is further enhanced by the non-linear evolution. We also find, in contrast with previous work, that the density profiles of cold dark matter halos are less concentrated in coupled dark energy cosmologies compared with ?CDM. Also, the baryon fraction in halos in the coupled models is significantly reduced below the universal baryon fraction. These features alleviate tensions between observations and the ?CDM model on small scales. Our methodology is ideally suited to explore the predictions of coupled dark energy models in the fully non-linear regime, which can provide powerful constraints for the viable parameter space of such scenarios. (orig.)

2009-01-01

188

Energy security and climate policy. Assessing interactions  

Energy Technology Data Exchange (ETDEWEB)

World energy demand is surging. Oil, coal and natural gas still meet most global energy needs, creating serious implications for the environment. One result is that CO2 emissions, the principal cause of global warming, are rising. This new study underlines the close link between efforts to ensure energy security and those to mitigate climate change. Decisions on one side affect the other. To optimise the efficiency of their energy policy, OECD countries must consider energy security and climate change mitigation priorities jointly. The book presents a framework to assess interactions between energy security and climate change policies, combining qualitative and quantitative analyses. The quantitative analysis is based on the development of energy security indicators, tracking the evolution of policy concerns linked to energy resource concentration. The 'indicators' are applied to a reference scenario and CO2 policy cases for five case-study countries: The Czech Republic, France, Italy, the Netherlands, and the United Kingdom. Simultaneously resolving energy security and environmental concerns is a key challenge for policy makers today. This study helps chart the course.

NONE

2007-03-28

189

Iron-catalyzed intermolecular hydroamination of styrenes.  

Science.gov (United States)

An iron-catalyzed formal hydroamination of alkenes has been developed. It features O-benzoyl-N,N-dialkylhydroxylamines as the electrophilic nitrogen source and cyclopentylmagnesium bromide as the reducing agent for intermolecular hydroamination of styrene and derivatives with good yield and excellent Markovnikov regioselectivity. The reaction presumably proceeds through the iron-catalyzed hydrometalation of styrene followed by electrophilic amination with the electrophilic O-benzoylhydroxylamine. PMID:24983840

Huehls, C Bryan; Lin, Aijun; Yang, Jiong

2014-07-18

190

Holographic dark energy interacting with dark matter  

CERN Document Server

We investigate a spatially flat Friedmann-Robertson-Walker (FRW) cosmological model with cold dark matter coupled to a dark energy which is given by the modified holographic Ricci cutoff. The interaction used is linear in both dark energy densities, the total energy density and its derivative. Using the statistical method of $\\chi^2$-function for the Hubble data, we obtain $H_0=73.6km/sMpc$, $\\omega_s=\\gamma_s -1=-0.842$ for the asymptotic equation of state and $ z_{acc}= 0.89 $. The estimated values of $\\Omega_{c0}$ which fulfill the current observational bounds corresponds to a dark energy density varying in the range $0.25R < \\ro_x < 0.27R$.

Forte, Mónica I

2012-01-01

191

Proton-nucleus interaction at high energy  

International Nuclear Information System (INIS)

The interaction of high energy protons (between 100 MeV and 20 GeV incident energy) with nuclei is studied in the frame of an intranuclear cascade (INC) model. Particular attention is paid to the energy loss of the projectile and on the emission patterns. It is shown that, in general, the incident proton has left the nucleus before the emission process starts. The latter proceeds first on a rather short time scale and involves fast particles. Progressively the emission rate slows down and the ejected particles are less rapid. The target mass, energy and impact parameter dependences of the energy loss is displayed. As a by-product, we calculate the nuclear stopping power. We investigate the fluctuations in the number of primary collisions, i.e. those suffered by the incoming nucleon, and in the energy loss. Fluctuations in the number of ejectiles are also studied as well as the relationship between primary collisions and the number of fast (grey) particles. The latter number is tentatively related with the number of site vacancies in percolation models. The entropy created inside the target is also calculated. It is shown that the representative point of the system in the (internal energy, entropy) plane spends a relatively long time in the coexistence zone and even in the instability zone corresponding to gas-liquid transition. Implications for these two models of fragmentation are discussed. A preliminary comparison with energy loss measurements in the 3-4 GeV/c range is performed. (orig.)

1987-02-09

192

Low energy weak interactions and decays  

International Nuclear Information System (INIS)

Results presented during sessions B5 to 7 at the XXth International Conference on High Energy Physics (University of Wisconsin, Madison, July 17 to 23, 1980) are discussed. Essentially all the material presented is summarized. The sessions covered various aspects of low-energy weak interactions. The following topics are addressed: CP-invariance violation, high-statistics study of ? beta decay, parity violation in proton-nucleus scattering at 6 GeV/c, new results on the tau, charm particle decays (direct lifetime determinations, semileptonic branching ratios, comparison of semileptonic rate with theoretical expectations, further study of charm meson decays, F decays), and neutrino oscillations. 6 figures, 9 tables

1980-07-23

193

Energy derivatives for configuration interaction wave functions  

International Nuclear Information System (INIS)

Equations providing the first and second derivatives of a configuration interaction (CI) energy with respect to an external parameter are provided. We assume no restriction on the form of the CI expansion built from molecular orbitals obtained in a multiconfiguration Hartree--Fock (MCHF) calculation. Also, the coupled perturbed multiconfiguration Hartree-Fock formalism is presented for a general MCHF wave function and provides the first order and second order changes of the molecular orbital expansion coefficients with respect to an external parameter

1981-05-15

194

Interactions of ultrahigh-energy neutrinos  

International Nuclear Information System (INIS)

Cross sections for the charged-current interactions of ultrahigh-energy neutrinos with nucleons are evaluated in light of recent improvements in our knowledge of nucleon structure functions. For 10/sup 19/-eV neutrinos, the cross section is an order of magnitude larger than the values traditionally used in astrophysical calculations. Some consequences for event rates from generic astrophysical neutrino sources are noted

1986-08-11

195

Interactions of quarkonium at low energies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present two examples of the short-distance QCD calculations for the quarkonium (\\Phi) interactions; 1) \\pi \\Phi elastic and \\pi \\Phi -> \\pi \\Phi' cross sections, and 2) the potential between two \\Phi's. The former is relevant for the \\Phi suppression in heavy ion collisions; we find that the corresponding cross sections are very small. For the latter we derive the sum rule which relates the strength of the potential to the energy density of the QCD vacuum. The key startin...

Fujii, H.; Kharzeev, D.

1999-01-01

196

Intermolecular electron transfer promoted by directional donor-acceptor attractions in self-assembled diketopyrrolopyrrole-thiophene films.  

Science.gov (United States)

The photophysics of a symmetric triad consisting of two bithiophene (BT) units covalently linked to a central diketopyrrolopyrrole unit (DPP) has been investigated both in dichloromethane and in the thin film. The DPP-BT film exhibits a red-shifted low-energy absorption band compared to its solution, which is indicative of efficient ?-? interactions in the solid-state phase. The steady-state and time-resolved fluorescence results revealed that the photoluminescence was subjected to severe emission quenching when DPP-BT changes from its solution phase to its film form. Further femtosecond transient absorption studies clarified that rapid intermolecular electron transfer accounts for the considerable fluorescence quenching event. The structural characterization of DPP-BT nanobelts, based on GIXRD and SAED patterns, suggested that the composite may be self-assembled into a slipped face-to-face configuration in the film, providing compact interlayer D-A interactions. As a result, intermolecular electron transfer is promoted by the favorable donor-acceptor attractions between the adjacent molecules. Moreover, this packing configuration provides a moderate channel for charge transportation. The hole mobility, which was measured based on a single-belt field-effect transistor, was found to be around 0.07 cm(2) V(-1) s(-1). Our observation reveals the role of spatial orientation in photophysical processes and the consequential semiconductor performance, providing guidance for the development and self-assembly of new opto-electronic molecules. PMID:22951990

Liu, Huiying; Jia, Hui; Wang, Lanfen; Wu, Yishi; Zhan, Chuanlang; Fu, Hongbing; Yao, Jiannian

2012-11-01

197

Interaction Energy in Pairs of Pyrazidinium Ylide-Solvent Molecules Estimated by Spectral Means within the Cell Ternary Solution Model  

International Nuclear Information System (INIS)

Ternary solutions of three carbanion disubstituted pyrazidinium ylides in a binary solvent containing two kinds of miscible simple liquids (active and inactive ones from the point of view of intermolecular interactions) are studied. Electronic absorption spectra are used to estimate the average statistical weights of the two solvents in the first solvation sphere of pyrazidinium ylide molecules. This sphere contains a higher number of active solvent molecules than the rest of the solution. The relation established between the average statistical weights in the first solvation sphere and the molar concentrations of the two solvents in the solution allows us to evaluate the interaction energy in molecular pairs of the type pyrazidinium ylide-active solvent and pyrazidinium ylide-inactive solvent.

2012-02-01

198

The interaction region of high energy protons  

CERN Document Server

New experimental data about proton-proton collisions obtained at the LHC allow to widen strongly the energy interval where one gets some knowledge about the structure of their interaction region. Using the data about the elastic scattering, it is shown how the shape and the darkness of the interaction region of colliding protons change with increase of their energies. In particular, the collisions become fully absorptive at small impact parameters at LHC energies that results in some special features of inelastic processes as well. Possible evolution of the shape from the dark core at the LHC to the fully transparent one is discussed that implies the terminology of the black disk would be replaced by the black torus. The parameter which determines the opacity of central collisions also plays a crucial role in the behavior of the differential cross section of elastic scattering outside the diffraction cone where the predictions of all phenomenological models failed at LHC energies. The role of the ratio of rea...

Dremin, I M

2014-01-01

199

Dark matter interacts with variable vacuum energy  

CERN Document Server

We investigate a spatially flat Friedmann-Robertson-Walker (FRW) scenario with two interacting components, dark matter and variable vacuum energy (VVE) densities, plus two decoupled components, one is a baryon term while the other behaves as a radiation component. We consider a linear interaction in the derivative dark component density. We apply the $\\chi^2$ method to the observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era for the model. It turns out that our model fulfills the severe bound of $\\Omega_{x}(z\\simeq 1100)<0.009$ at $2\\sigma$ level, so is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from Planck survey, the future constraints achievable by Euclid and CMBPol experiments, reported for the behavior of the dark energy at early times, and fulfills the stringent bound $\\Omega_{x}(z\\simeq 10^{10})<0.04$ at $2\\sigma$ level in the big-bang nucleosynthesis epoch. We a...

G, Iván E Sánchez

2014-01-01

200

Digital communication through intermolecular fluorescence modulation.  

Science.gov (United States)

[see reaction]. Ultraminiaturized processors incorporating molecular components can be developed only after devising efficient strategies to communicate signals at the molecular level. We have demonstrated that a three-state molecular switch responds to ultraviolet light, visible light, and H+, attenuating the emission intensity of a fluorescent probe. Intermolecular communication is responsible for the transduction of three input signals into a single optical output. The behavior of the communicating ensemble of molecules corresponds to that of a logic circuit incorporating seven gates. PMID:11405723

Raymo, F M; Giordani, S

2001-06-14

 
 
 
 
201

Determination of a silane intermolecular force field potential model from an ab initio calculation  

International Nuclear Information System (INIS)

Intermolecular interaction potentials of the silane dimer in 12 orientations have been calculated by using the Hartree-Fock (HF) self-consistent theory and the second-order Moeller-Plesset (MP2) perturbation theory. We employed basis sets from Pople's medium-size basis sets [up to 6-311++G(3df, 3pd)] and Dunning's correlation consistent basis sets (up to the triply augmented correlation-consistent polarized valence quadruple-zeta basis set). We found that the minimum energy orientations were the G and H conformers. We have suggested that the Si-H attractions, the central silicon atom size, and electronegativity play essential roles in weakly binding of a silane dimer. The calculated MP2 potential data were employed to parametrize a five-site force field for molecular simulations. The Si-Si, Si-H, and H-H interaction parameters in a pairwise-additive, site-site potential model for silane molecules were regressed from the ab initio energies.

2010-12-01

202

[High-energy electron-positron interactions  

International Nuclear Information System (INIS)

The purpose of the research was the study of electron-positron interactions at high energies using the Time Projection Chamber (TPC) at the Positron Electron Project (PEP) at SLAC. The TPC detector had an initial data gathering from 1982 until 1986 and accumulated a data sample with an integrated luminosity of -150 pb-1 at an electron-positron energy of 29 GeV. The data runs in the 1988--1990 time period (yielding ? pb-1) were abbreviated, due to the need of the laboratory to give highest priority to the new Stanford Linear Collider (SLC). The TPC collaboration decided in 1991 to discontinue data taking, but has continued the collaboration for the purpose of completing the analysis of the data. When UMass joined the SLD project, it was being designed as a new state-of-the-art detector for studying electron-positron interactions at energies in the vicinity of 91 GeV, the Z0 mass. The detector was completed and installed at the interaction point of the SLC in 1991, at which time an initial, ''engineering run'' allowed the debugging of detector components and provided a data sample of ?1,000 events with hadronic Z0 decays. In 1992 the SLC provided beams of polarized electrons and the SLD collected a data sample in excess of 11,000 hadronic Z0 events produced by polarized electrons, allowing unique measurements of some of the parameters of the standard model. This project is continuing to take data in 1993 with increased polarization and higher luminosity. This report reviews the research work performed under the contract, and survey's the physics results

1993-01-01

203

Correlations in high-energy interactions  

International Nuclear Information System (INIS)

The short-range correlations in rapidity whose existence has been firmly established in high-energy interactions are used to explain chaotic multiplicity behavior in proton-nucleon collisions at 800 GeV. In order to determine the values of higher-order moments from the second-order moment, we have used the pure birth approximation which is in agreement with the ''linked pair'' approximation of Carruthers. The calculated values of the normalized factorial moments for a given bin size show a good agreement with our data

1994-09-01

204

Low energy atomic collision with dipole interactions  

CERN Document Server

We apply quantum defect theory to study low energy ground state atomic collisions including aligned dipole interactions such as those induced by an electric field. We present and compare results from model short-range potentials for typical alkali metal atoms in spin-singlet and -triplet states. Our results show that coupled even ($l$) relative orbital angular momentum partial wave channels exhibit shape resonance structures while odd ($l$) channels do not. We analyze and interpret these resonances within the framework of multichannel quantum defect theory (MQDT).

Deb, B

2001-01-01

205

Weak interactions at high energies. [Lectures, review  

Energy Technology Data Exchange (ETDEWEB)

Review lectures are presented on the phenomenological implications of the modern spontaneously broken gauge theories of the weak and electromagnetic interactions, and some observations are made about which high energy experiments probe what aspects of gauge theories. Basic quantum chromodynamics phenomenology is covered including momentum dependent effective quark distributions, the transverse momentum cutoff, search for gluons as sources of hadron jets, the status and prospects for the spectroscopy of fundamental fermions and how fermions may be used to probe aspects of the weak and electromagnetic gauge theory, studies of intermediate vector bosons, and miscellaneous possibilities suggested by gauge theories from the Higgs bosons to speculations about proton decay. 187 references. (JFP)

Ellis, J.

1978-08-01

206

ENERGY DERIVATIVES FOR CONFIGURATION INTERACTION WAVEFUNCTIONS  

Energy Technology Data Exchange (ETDEWEB)

Equations providing the first and second derivatives of a configuration interaction (CI) energy with respect to an external parameter are provided. We assume no restriction on the form of the CI expansion built from molecular orbitals obtained in a multiconfiguration Hartree-Fock (MCHF) calculation. Also the coupled perturbed multi-configuration Hartree-Fock formalism is presented for a general MCHF wavefunction and provides the first order and second order changes of the molecular orbital expansion coefficients with respect to an external parameter.

Dupuis, M.

1980-09-01

207

A simple and reliable approach to docking protein-protein complexes from very sparse NOE-derived intermolecular distance restraints  

International Nuclear Information System (INIS)

A simple and reliable approach for docking protein-protein complexes from very sparse NOE-derived intermolecular distance restraints (as few as three from a single point) in combination with a novel representation for an attractive potential between mapped interaction surfaces is described. Unambiguous assignments of very sparse intermolecular NOEs are obtained using a reverse labeling strategy in which one the components is fully deuterated with the exception of selective protonation of the ?-methyl groups of isoleucine, while the other component is uniformly 13C-labeled. This labeling strategy can be readily extended to selective protonation of Ala, Leu, Val or Met. The attractive potential is described by a 'reduced' radius of gyration potential applied specifically to a subset of interfacial residues (those with an accessible surface area ? 50% in the free proteins) that have been delineated by chemical shift perturbation. Docking is achieved by rigid body minimization on the basis of a target function comprising the sparse NOE distance restraints, a van der Waals repulsion potential and the 'reduced' radius of gyration potential. The method is demonstrated for two protein-protein complexes (EIN-HPr and IIAGlc-HPr) from the bacterial phosphotransferase system. In both cases, starting from 100 different random orientations of the X-ray structures of the free proteins, 100% convergence is achieved to a single cluster (with near identical atomic positions) with an overall backbone accuracy of ?2 A. The approach described is not limited to NMR, since interfaces can also be mapped by alanine scanning mutagenesis, and sparse intermolecular distance restraints can be derived from double cycle mutagenesis, cross-linking combined with mass spectrometry, or fluorescence energy transfer

2006-09-01

208

A new intermolecular mechanism to selectively drive photoinduced damages  

CERN Document Server

Low-energy electrons (LEEs) are known to be effective in causing strand breaks in DNA. Recent experiments show that an important direct source of LEEs is the intermolecular Coulombic decay (ICD) process. Here we propose a new cascade mechanism initiated by core excitation and terminated by ICD and demonstrate its properties. Explicit calculations show that the energies of the emitted ICD-electrons can be controlled by selecting the initial atomic excitation. The properties of the cascade may have interesting applications in the fields of electron spectroscopy and radiation damage. Initiating such a cascade by resonant X-ray absorption from a high-Z element embedded in a cancerous cell nucleus, ICD will deliver genotoxic particles \\textit{locally} at the absorption site, increasing in that way the controllability of the induced damage.

Gokhberg, Kirill; Kuleff, Alexander I; Cederbaum, Lorenz S

2014-01-01

209

An assay for intermolecular exchange of alpha crystallin  

Science.gov (United States)

An affinity column of alpha crystallin linked to cyanogen bromide-activated Sepharose was developed to study the exchange of alpha subunits. Alpha crystallin bound to the Sepharose-alpha complex was dissociated with 8 mol/l urea, followed by quantitation using high-performance reverse-phase liquid chromatography. The time course of binding at 37 degrees C showed a hyperbolic binding pattern reaching equilibrium between 6-18 hr. Under these conditions, binding of beta and gamma crystallins to the same matrix was less than 10% of the alpha values, as was binding of alpha to glycine-coupled Sepharose. This assay was used to demonstrate changes in the subunit exchange of alpha crystallins present in high molecular weight versus lower molecular weight aggregates of the human lens. These results show that this binding procedure was a specific reproducible assay that might be used to study intermolecular interactions of the alpha crystallins.

Gopalakrishnan, S.; Takemoto, L.; Spooner, B. S. (Principal Investigator)

1992-01-01

210

Strongly Interacting Matter at High Energy Density  

Energy Technology Data Exchange (ETDEWEB)

This lecture concerns the properties of strongly interacting matter (which is described by Quantum Chromodynamics) at very high energy density. I review the properties of matter at high temperature, discussing the deconfinement phase transition. At high baryon density and low temperature, large N{sub c} arguments are developed which suggest that high baryonic density matter is a third form of matter, Quarkyonic Matter, that is distinct from confined hadronic matter and deconfined matter. I finally discuss the Color Glass Condensate which controls the high energy limit of QCD, and forms the low x part of a hadron wavefunction. The Glasma is introduced as matter formed by the Color Glass Condensate which eventually thermalizes into a Quark Gluon Plasma.

McLerran,L.

2008-09-07

211

Proton-Nucleus Interactions at Tevatron Energy  

Energy Technology Data Exchange (ETDEWEB)

Proton-nucleus interactions at Tevatron highest energy are studied by using the different target nuclei (aluminum, copper, tin and tungsten). Particle production mechanism in pA collision can be studied through target mass dependence on angular distribution of secondary charged particle as well as multiplicity distribution with various target nuclei of aluminum, copper, tin and tungsten. Considering the result of previous 400 GeV/c proton-nucleus experiment by means of nuclear emulsion chamber, we can also investigate energy dependence of various quantities such as momenta in multiplicity distribution, rapidity density and absorption cross sections. We propose to perform same kind of exposure as previous experiment but by 800 GeV proton beam.

Ogata, T.; Tabuki, T.; /Tokyo U.; Dake, S.; Nakata, K.; Oda, H.; /Kobe U.; Tominaga, T.; /Osaka U.; Fuki, M.; /Okayama U.

1985-01-01

212

Interaction Energy of `t Hooft-Polyakov Monopoles  

CERN Multimedia

The dependence of the energies of axially symmetric monopoles of magnetic charges 2 and 3, on the Higgs self-interaction coupling constant, is studied numerically. Comparing the energy per unit topological charge of the charge-2 monopole with the energy of the spherically symmetric charge-1 monopole, we confirm that there is only a repulsive phase in the interaction energy between like monopoles

Kleihaus, B; Tchrakian, D H

1998-01-01

213

Inelastic x-ray scattering of dense solid oxygen: Evidence for intermolecular bonding  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The detailing of the intermolecular interactions in dense solid oxygen is essential for an understanding of the rich polymorphism and remarkable properties of this element at high pressure. Synchrotron inelastic x-ray scattering measurements of oxygen K-edge excitations to 38 GPa reveal changes in electronic structure and bonding on compression of the molecular solid. The measurements show that O2 molecules interact predominantly through the half-filled 1?g* orbital <10 GPa. Enhanced intermo...

Meng, Yue; Eng, Peter J.; Tse, John S.; Shaw, Dawn M.; Hu, Michael Y.; Shu, Jinfu; Gramsch, Stephen A.; Kao, Chichang; Hemley, Russell J.; Mao, Ho-kwang

2008-01-01

214

Application of charge density methods to a protein model compound: Calculation of Coulombic intermolecular interaction energies from the experimental charge density  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A combined experimental and theoretical charge density study of the pentapeptide Boc-Gln-d-Iva-Hyp-Ala-Phol (Boc, butoxycarbonyl; Gln, glutamine; Iva, isovaline; Hyp, hydroxyproline; Ala, ethylalanine; Phol, phenylalaninol) is described. The experimental analysis, based on synchrotron x-ray data collected at 20 K, is combined with ab initio theoretical calculations. The topologies of the experimental and theoretical densities are analyzed in terms of the atoms in molecules quantum theory. Top...

Li, Xue; Wu, Guang; Abramov, Yuriy A.; Volkov, Anatoliy V.; Coppens, Philip

2002-01-01

215

Intermolecular vibrations of fluorobenzene-Ar up to 130 cm-1 in the ground electronic state  

Science.gov (United States)

Sixteen intermolecular vibrational levels of the S0 state of the fluorobenzene-Ar van der Waals complex have been observed using dispersed fluorescence. The levels range up to ~130 cm-1 in vibrational energy. The vibrational energies have been modelled using a complete set of harmonic and quartic anharmonic constants and a cubic anharmonic coupling between the stretch and long axis bend overtone that becomes near ubiquitous at higher energies. The constants predict the observed band positions with a root mean square deviation of 0.04 cm-1. The set of vibrational levels predicted by the constants, which includes unobserved bands, has been compared with the predictions of ab initio calculations, which include all vibrational levels up to 70-75 cm-1. There are small differences in energy, particularly above 60 cm-1, however, the main differences are in the assignments and are largely due to the limitations of assigning the ab initio wavefunctions to a simple stretch, bend, or combination when the states are mixed by the cubic anharmonic coupling. The availability of these experimental data presents an opportunity to extend ab initio calculations to higher vibrational energies to provide an assessment of the accuracy of the calculated potential surface away from the minimum. The intermolecular modes of the fluorobenzene-Ar2 trimer complex have also been investigated by dispersed fluorescence. The dominant structure is a pair of bands with a ~35 cm-1 displacement from the origin band. Based on the set of vibrational modes calculated from the fluorobenzene-Ar frequencies, they are assigned to a Fermi resonance between the symmetric stretch and symmetric short axis bend overtone. The analysis of this resonance provides a measurement of the coupling strength between the stretch and short axis bend overtone in the dimer, an interaction that is not directly observed. The coupling matrix elements determined for the fluorobenzene-Ar stretch-long axis bend overtone and stretch-short axis bend overtone couplings are remarkably similar (3.8 cm-1 cf. 3.2 cm-1). Several weak features seen in the fluorobenzene-Ar2 spectrum have also been assigned.

Gascooke, Jason R.; Alexander, Ula N.; Lawrance, Warren D.

2012-08-01

216

Theoretical study of intermolecular energy transfer involving electronically excited molecules: He(/sup 1/S) + H/sub 2/(B /sup 1/. sigma. /sub u//sup +/). [Solution for coupled channel equations  

Energy Technology Data Exchange (ETDEWEB)

To further understanding of gas phase collision dynamics involving electronically-excited molecules, a fully quantum mechanical study of He + H/sub 2/(B /sup 1/..sigma../sub u//sup +/) was undertaken. Iterative natural orbital configuration interaction (CI) calculations were performed to obtain the interaction potential between He and H/sub 2/(B /sup 1/..sigma../sub u//sup +/). The potential energy surface (PES) is highly anisotropic and has a van der Waals well of about 0.03 eV for C/sub 2v/ approach. Avoided PES crossings occur with He + H/sub 2/(E,F /sup 1/..sigma../sub g//sup +/) and with He + H/sub 2/(X /sup 1/..sigma../sub g//sup +/) and cause a local maximum and a deep minimum in the He + H/sub 2/(B /sup 1/..sigma../sub u//sup +/) PES, respectively. The crossing with He + H/sub 2/(X /sup 1/..sigma../sub g//sup +/) provides a mechanism for fluorescence quenching. The computed CI energies were combined with previous multi-reference double excitation CI calculations and fit with analytic functions for convenience in scattering calculations. Accurate dipole polarizabilities and quadrupole moment of H/sub 2/(B /sup 1/..sigma../sub u//sup +/) were computed for use in the multipole expansion, which is the analytic form of the long-range PES. 129 refs., 28 figs., 35 tabs.

Grimes, R.M.

1986-11-01

217

Optimized intermolecular potential functions for liquid hydrocarbons  

Energy Technology Data Exchange (ETDEWEB)

Optimized intermolecular potential functions have been determined for hydrocarbons through Monte Carlo simulations of 15 liquids: methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, cyclopentane, n-hexane, 1-butene, cis- and trans-2-butene, isobutene, and benzene. To achieve high accuracy, 12 unique group types were identified and their associated Lennard-Jones parameters were established. The average deviation from experiment for the computed densities and heats of vaporization is 2% and trends for isomeric series are reproduced. Conformation results were also obtained for five liquids and revealed no condensed-phase effects on the conformer populations. Structural analyses focus on trends as a function of chain length and branching of the monomers.

Jorgensen, W.L.; Madura, J.D.; Swenson, C.J.

1984-10-31

218

Genome-wide expression profiling and mutagenesis studies reveal that lipopolysaccharide responsiveness appears to be absolutely dependent on TLR4 and MD-2 expression and is dependent upon intermolecular ionic interactions.  

Science.gov (United States)

Lipid A (a hexaacylated 1,4' bisphosphate) is a potent immune stimulant for TLR4/MD-2. Upon lipid A ligation, the TLR4/MD-2 complex dimerizes and initiates signal transduction. Historically, studies also suggested the existence of TLR4/MD-2-independent LPS signaling. In this article, we define the role of TLR4 and MD-2 in LPS signaling by using genome-wide expression profiling in TLR4- and MD-2-deficient macrophages after stimulation with peptidoglycan-free LPS and synthetic Escherichia coli lipid A. Of the 1396 genes significantly induced or repressed by any one of the treatments in the wild-type macrophages, none was present in the TLR4- or MD-2-deficient macrophages, confirming that the TLR4/MD-2 complex is the only receptor for endotoxin and that both are required for responses to LPS. Using a molecular genetics approach, we investigated the mechanism of TLR4/MD-2 activation by combining the known crystal structure of TLR4/MD-2 with computer modeling. According to our murine TLR4/MD-2-activation model, the two phosphates on lipid A were predicted to interact extensively with the two positively charged patches on mouse TLR4. When either positive patch was abolished by mutagenesis into Ala, the responses to LPS and lipid A were nearly abrogated. However, the MyD88-dependent and -independent pathways were impaired to the same extent, indicating that the adjuvant activity of monophosphorylated lipid A most likely arises from its decreased potential to induce an active receptor complex and not more downstream signaling events. Hence, we concluded that ionic interactions between lipid A and TLR4 are essential for optimal LPS receptor activation. PMID:21865549

Meng, Jianmin; Gong, Mei; Björkbacka, Harry; Golenbock, Douglas T

2011-10-01

219

Structure, vibrational spectra and DFT characterization of the intra- and inter-molecular interactions in 2-hydroxy-5-methylpyridine-3-carboxylic acid--normal modes of the eight-membered HB ring.  

Science.gov (United States)

Fourier transform IR and Raman spectra, XRD studies and DFT quantum chemical calculations have been used to characterize the structural and vibrational properties of 2-hydroxy-5-methylpyridine-3-carboxylic acid. In the unit-cell of this compound two molecules related by the inversion center interact via OH?N hydrogen bonds. The double hydrogen bridge system is spaced parallel to the (102) crystallographic plane forming eight-membered arrangement characteristic for pyridine derivatives. The six-membered ring is the second characteristic unit formed via the intramolecular OH?O hydrogen bond. The geometry optimization of the monomer and dimer have been performed applying the Gaussian03 program package. All calculations were performed in the B3LYP/6-31G(d,p) basis set using the XRD data as input parameters. The relation between the molecular and crystal structures has been discussed in terms of the hydrogen bonds formed in the unit cell. The vibrations of the dimer have been discussed in terms of the resonance inside the system built of five rings coupled via hydrogen bonds. PMID:24184924

Godlewska, P; Ja?czak, J; Kucharska, E; Hanuza, J; Lorenc, J; Michalski, J; Dymi?ska, L; W?gli?ski, Z

2014-02-24

220

Interacting Ricci Dark Energy and its Statefinder Description  

CERN Multimedia

In this paper we have considered an interacting Ricci dark energy in flat FRW universe. We have reconstructed the Hubble's parameter under this interaction. Also, we have investigated the statefinder diagnostics. It has been revealed that the equation of state parameter behaves like quintessence in this interaction and from the statefinder diagnostics it has been concluded that the interacting Ricci dark energy interpolates between dust and $\\Lambda$CDM stages of the universe.

Chattopadhyay, Surajit

2012-01-01

 
 
 
 
221

IMPROPER HYDROGEN BONDS - A THEORETICAL STUDY ABOUT THE MOLECULAR STRUCTURE OF INTERMOLECULAR SYSTEMS FORMED BY H3C-H+?...X AND H3C+?...H-Y WITH X = CL- OR F- AND Y = CL OR F  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english In this work is presented a theoretical study of the molecular properties of the H3C-H...X and H3C+?...H-Y intermolecular systems with X = CL- or F- and Y = Cl or F. In the H3C-H...X complex, it is formed a traditional hydrogen bond between the CL- or F- anions and the hydrogen atom of the meth [...] yl. About the H3C+?...H-Y complex, it was observed an improper hydrogen bond because the carbon atom of the methyl cation function as a proton acceptor. In this insight, the capacity of methane to interact with halogen anions (CL- or F-) and molecular acids (HCl or HF) was examined at the B3LYP/6-311++G(3df,3dp) level of calculation. Moreover, the interaction strengths of the H3C-H...X and H3C+?...H-Y complexes was evaluated by computing their intermolecular distances and binding energies. Finally, QTAIM calculations also were executed with the purpose to examine the intermolecular interactions through the quantification of their electronic densities (p) as well as by the interpretation of the Laplacian operators ().

OLIVEIRA, B.G.

222

IMPROPER HYDROGEN BONDS - A THEORETICAL STUDY ABOUT THE MOLECULAR STRUCTURE OF INTERMOLECULAR SYSTEMS FORMED BY H3C-H+?...X AND H3C+?...H-Y WITH X = CL- OR F- AND Y = CL OR F  

Directory of Open Access Journals (Sweden)

Full Text Available In this work is presented a theoretical study of the molecular properties of the H3C-H...X and H3C+?...H-Y intermolecular systems with X = CL- or F- and Y = Cl or F. In the H3C-H...X complex, it is formed a traditional hydrogen bond between the CL- or F- anions and the hydrogen atom of the methyl. About the H3C+?...H-Y complex, it was observed an improper hydrogen bond because the carbon atom of the methyl cation function as a proton acceptor. In this insight, the capacity of methane to interact with halogen anions (CL- or F- and molecular acids (HCl or HF was examined at the B3LYP/6-311++G(3df,3dp level of calculation. Moreover, the interaction strengths of the H3C-H...X and H3C+?...H-Y complexes was evaluated by computing their intermolecular distances and binding energies. Finally, QTAIM calculations also were executed with the purpose to examine the intermolecular interactions through the quantification of their electronic densities (p as well as by the interpretation of the Laplacian operators (.

B.G OLIVEIRA

2009-01-01

223

Intermolecular correlations and mean square relative displacements in C{sub 60} fullerite  

Energy Technology Data Exchange (ETDEWEB)

We study molecular properties of the high-temperature modification of fullerites. In the present work we calculate the intermolecular correlations and the mean square relative displacements in C{sub 60}. The Girifalco intermolecular potential is utilized. The calculations have been made in the whole interval from the equilibrium point with orientationally ordered phase up to the spinodal temperature. To take into account the lattice anharmonicity we use the correlative method of unsymmetrized self-consistent field. Its second order allows one to investigate correlations in fcc lattice between the nearest, second, third and fourth neighbors. The anharmonicity has strong effect on the intermolecular correlations at T > 700 K, causing their drastic rise near the spinodal point. The dependence of the correlation moments on the distance between molecules and on the crystallographic direction is considered. We compare our results with those for solid Ar and discuss the influence of a special feature of the interaction potentials on the intermolecular correlations and the mean square molecular displacements. (orig.)

Zubov, V.I. [Goias Univ., Goiania (Brazil). Dept. de Fisica; Universitet Druzhby Narodov, Moscow (Russian Federation). Dept. of Theoretical Physics; Rodrigues, C.G. [Univ. de Catolica de Goias (Brazil). Nucleo de Pesquisa em Fisica

2000-12-01

224

Resonant Auger decay driving intermolecular Coulombic decay in molecular dimers  

Science.gov (United States)

In 1997, it was predicted that an electronically excited atom or molecule placed in a loosely bound chemical system (such as a hydrogen-bonded or van-der-Waals-bonded cluster) could efficiently decay by transferring its excess energy to a neighbouring species that would then emit a low-energy electron. This intermolecular Coulombic decay (ICD) process has since been shown to be a common phenomenon, raising questions about its role in DNA damage induced by ionizing radiation, in which low-energy electrons are known to play an important part. It was recently suggested that ICD can be triggered efficiently and site-selectively by resonantly core-exciting a target atom, which then transforms through Auger decay into an ionic species with sufficiently high excitation energy to permit ICD to occur. Here we show experimentally that resonant Auger decay can indeed trigger ICD in dimers of both molecular nitrogen and carbon monoxide. By using ion and electron momentum spectroscopy to measure simultaneously the charged species created in the resonant-Auger-driven ICD cascade, we find that ICD occurs in less time than the 20femtoseconds it would take for individual molecules to undergo dissociation. Our experimental confirmation of this process and its efficiency may trigger renewed efforts to develop resonant X-ray excitation schemes for more localized and targeted cancer radiation therapy.

Trinter, F.; Schöffler, M. S.; Kim, H.-K.; Sturm, F. P.; Cole, K.; Neumann, N.; Vredenborg, A.; Williams, J.; Bocharova, I.; Guillemin, R.; Simon, M.; Belkacem, A.; Landers, A. L.; Weber, Th.; Schmidt-Böcking, H.; Dörner, R.; Jahnke, T.

2014-01-01

225

Vibrational nano-spectroscopic imaging correlating structure with intermolecular coupling and dynamics  

Science.gov (United States)

Molecular self-assembly, the function of biomembranes and the performance of organic solar cells rely on nanoscale molecular interactions. Understanding and control of such materials have been impeded by difficulties in imaging their properties with the desired nanometre spatial resolution, attomolar sensitivity and intermolecular spectroscopic specificity. Here we implement vibrational scattering-scanning near-field optical microscopy with high spectral precision to investigate the structure–function relationship in nano-phase separated block copolymers. A vibrational resonance is used as a sensitive reporter of the local chemical environment and we image, with few nanometre spatial resolution and 0.2?cm?1 spectral precision, solvatochromic Stark shifts and line broadening correlated with molecular-scale morphologies. We discriminate local variations in electric fields between nano-domains with quantitative agreement with dielectric continuum models. This ability to directly resolve nanoscale morphology and associated intermolecular interactions can form a basis for the systematic control of functionality in multicomponent soft matter systems.

Pollard, Benjamin; Muller, Eric A.; Hinrichs, Karsten; Raschke, Markus B.

2014-04-01

226

Very High Energy Cosmic Rays and Their Interactions  

International Nuclear Information System (INIS)

The investigation of high energy cosmic rays and their interactions is a very active field of research. This article summarizes the progress made during the last years as reflected by the contributions to the XIII International Symposium on Very High Energy Cosmic Ray Interactions held in Pylos, Greece

2006-01-01

227

Very High Energy Cosmic Rays and Their Interactions  

Energy Technology Data Exchange (ETDEWEB)

The investigation of high energy cosmic rays and their interactions is a very active field of research. This article summarizes the progress made during the last years as reflected by the contributions to the XIII International Symposium on Very High Energy Cosmic Ray Interactions held in Pylos, Greece.

Engel, Ralph [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, 76021 Karlsruhe (Germany)

2006-01-15

228

Very High Energy Cosmic Rays and Their Interactions  

Science.gov (United States)

The investigation of high energy cosmic rays and their interactions is a very active field of research. This article summarizes the progress made during the last years as reflected by the contributions to the XIII International Symposium on Very High Energy Cosmic Ray Interactions held in Pylos, Greece.

Engel, Ralph

2006-01-01

229

Very High Energy Cosmic Rays and Their Interactions  

CERN Document Server

The investigation of high energy cosmic rays and their interactions is a very active field of research. This article summarizes the progress made during the last years as reflected by the contributions to the XIII International Symposium on Very High Energy Cosmic Ray Interactions held in Pylos, Greece.

Engel, R

2005-01-01

230

Thermodynamical description of the interacting new agegraphic dark energy  

CERN Multimedia

We describe the thermodynamical interpretation of the interaction between new agegraphic dark energy and dark matter in a non-flat universe. When new agegraphic dark energy and dark matter evolve separately, each of them remains in thermodynamic equilibrium. As soon as an interaction between them is taken into account, their thermodynamical interpretation changes by a stable thermal fluctuation. We obtain a relation between the interaction term of the dark components and this thermal fluctuation.

Sheykhi, A

2009-01-01

231

Breaking parameter degeneracy in interacting dark energy models from observations  

International Nuclear Information System (INIS)

We study the interacting dark energy model with time varying dark energy equation of state. We examine the stability in the perturbation formalism and the degeneracy among the coupling between dark sectors, the time-dependent dark energy equation of state and dark matter abundance in the cosmic microwave background radiation. Further we discuss the possible ways to break such degeneracy by doing global fitting using the latest observational data and we get a tight constraint on the interaction between dark sectors.

2011-07-27

232

Computational estimation of specific side chain interaction energies in ? helices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have used a structure energy-based computer program developed for protein design, Perla, to provide theoretical estimates of all specific side chain–side chain interaction energies occurring in ? helices. The computed side chain–side chain interaction energies were used as substitutes for the corresponding values used by the helix/coil transition algorithm, AGADIR. Predictions of peptide helical contents were nearly as successful as those obtained with the originally calibrated set of...

2001-01-01

233

Interaction energies between glycopeptide antibiotics and substrates in complexes determined by X-ray crystallography: application of a theoretical databank of aspherical atoms and a symmetry-adapted perturbation theory-based set of interatomic potentials.  

Science.gov (United States)

Intermolecular interaction energies between fragments of glycopeptide antibiotics and small peptide ligands are evaluated using geometries determined by X-ray crystallography and recently developed methods suitable for application to very large molecular complexes. The calculation of the electrostatic contributions is based on charge densities constructed with a databank of transferable aspherical atoms described by nucleus-centered spherical harmonic density functions, and uses the accurate and fast EPMM method. Dispersion, induction and exchange-repulsion contributions are evaluated with atom-atom potentials fitted to intermolecular energies from SAPT (symmetry-adapted perturbation theory) calculations on a large number of molecules. For a number of the complexes, first-principle calculations using density functional theory have been performed for comparison. Results of the new methods agree within reasonable bounds with those from DFT calculations, while being obtained at a fraction (less than 1%) of the computer time. A strong dependence on the geometry of the interaction is found, even when the number of hydrogen bonds between the substrate and antibiotic fragment is the same. While high-resolution X-ray data are required to obtain interaction energies at a quantitative level, the techniques developed have potential for joint X-ray/energy refinement of macromolecular structures. PMID:16699191

Li, Xue; Volkov, Anatoliy V; Szalewicz, Krzysztof; Coppens, Philip

2006-06-01

234

Exactly solved models of interacting dark matter and dark energy  

CERN Document Server

We introduce an effective one-fluid description of the interacting dark sector in a spatially flat Friedmann-Robertson-Walker space-time and investigate the stability of the power-law solutions. We find the "source equation" for the total energy density and determine the energy density of each dark component. We study linear and nonlinear interactions which depend on the dark matter and dark energy densities, their first derivatives, the total energy density with its derivatives up to second order and the scale factor. We solve the evolution equations of the dark components for both interactions, examine exhaustively several examples and show cases where the problem of the coincidence is alleviated. We show that a generic nonlinear interaction gives rise to the "relaxed Chaplygin gas model" whose effective equation of state includes the variable modified Chaplygin gas model while some others nonlinear interactions yield de Sitter and power-law scenarios.

Chimento, Luis P

2012-01-01

235

Dark Energy and Its Interactions with Neutrinos  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this talk I will firstly review on the current constraints on the equation of state of the dark energy from observational data, then present a new scenario of dark energy dubbed {\\it Quintom}. The recent fits to the type Ia supernova data and the cosmic microwave background and so on in the literature find that the behavior of dark energy is to great extent in consistency with a cosmological constant, however the dynamical dark energy scenarios are generally not ruled out...

Zhang, Xinmin

2005-01-01

236

Cosmological Evolution With Interaction Between Dark Energy And Dark Matter  

CERN Document Server

In this review we consider in detail different theoretical topics associated with interaction in the dark sector. We study linear and nonlinear interactions which depend on the dark matter and dark energy densities. We consider a number of different models (including the holographic dark energy and dark energy in a fractal universe) with interacting dark energy (DE) and dark matter (DM), have done a thorough analysis of these models. The main task of this review was not only to give an idea about the modern set of different models of dark energy, but to show how much can be diverse dynamics of the universe in these models. We find that the dynamics of a Universe that contains interaction in the dark sector can differ significantly from the Standard Cosmological Model (SCM).

Bolotin, Yu L; Lemets, O A; Yerokhin, D A

2013-01-01

237

The distinguishability of interacting dark energy from modified gravity  

Science.gov (United States)

We study the observational viability of coupled quintessence models with their expansion and growth histories matched to modified gravity cosmologies. We find that for a Dvali-Gabadadze-Porrati model which has been fitted to observations, the matched interacting dark energy models are observationally disfavoured. We also study the distinguishability of interacting dark energy models matched to scalar-tensor theory cosmologies and show that it is not always possible to find a physical interacting dark energy model which shares their expansion and growth histories.

Clemson, Timothy; Koyama, Kazuya

2013-01-01

238

The Distinguishability of Interacting Dark Energy from Modified Gravity  

CERN Document Server

We study the observational viability of coupled quintessence models with their expansion and growth histories matched to modified gravity cosmologies. We find that for a Dvali-Gabadadze-Porrati model which has been fitted to observations, the matched interacting dark energy models are observationally disfavoured. We also study the distinguishability of interacting dark energy models matched to scalar-tensor theory cosmologies and show that it is not always possible to find a physical interacting dark energy model which shares their expansion and growth histories.

Clemson, Timothy

2012-01-01

239

Low-energy pion-nucleon interaction  

International Nuclear Information System (INIS)

The situation in low-energy pion-nucleon scattering is reviewed, using an energy-dependent PWA as a tool. The method and some conclusions of this new PWA of ?N scattering data across the ?(1232) are summarized. In particular, the ''inconsistencies'' in the low-energy database are addressed, and the state-of-the-art of the NN? coupling constant and of the ?N ?-term is discussed. (orig.)

1998-03-02

240

Calculations of potential energy surfaces using Monte Carlo configuration interaction  

Science.gov (United States)

We apply the method of Monte Carlo configuration interaction (MCCI) to calculate ground-state potential energy curves for a range of small molecules and compare the results with full configuration interaction. We show that the MCCI potential energy curve can be calculated to relatively good accuracy, as quantified using the non-parallelity error, using only a very small fraction of the full configuration interaction space. In most cases the potential curve is of better accuracy than its constituent single-point energies. We finally test the MCCI program on systems with basis sets beyond full configuration interaction: a lattice of 50 hydrogen atoms and ethylene. The results for ethylene agree fairly well with other computational work while for the lattice of 50 hydrogens we find that the fraction of the full configuration interaction space we were able to consider appears to be too small as, although some qualitative features are reproduced, the potential curve is less accurate.

Coe, Jeremy P.; Taylor, Daniel J.; Paterson, Martin J.

2012-11-01

 
 
 
 
241

Interactions of ultrahigh-energy neutrinos  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Future detection of ultrahigh-energy neutrinos will open a new window on physics at center-of-mass energy 10^5 GeV and higher. In particular, observations of neutrino-initiated showers will help test the Standard Model predictions for the neutrino-nucleon cross section.

Kusenko, Alexander

2002-01-01

242

Hadron-nucleus interactions at high energy  

International Nuclear Information System (INIS)

Properties of energetic secondaries produced at large angles using 800 GeV incident protons are presented. H_2, Be, C, Al, Cu and Pb targets were used for the study. The yields for producing such secondaries vary as A/sup ?/ where A is the atomic mass number of the target and ? attains values as large as 1.6. There is evidence that jet-like events have ? values approaching unity, indicating a hard scattering mechanism may be occurring. Events with large values of target-fragmentation energy have, on average, large values of energy in the central region and small values of forward-going energy. Energy flows and number of secondaries are independent of the target when events with similar amounts of energy in the central region are studied

1986-04-08

243

Interacting Quintessence Models of Dark Energy  

CERN Document Server

In this paper we consider two models of quintessence scalar fields with different potentials. Interaction with generalized cosmic Chaplygin gas is also investigated. Cosmological parameters are studied and graphical behavior is analyzed. We find that our model is agree with observational data specially $\\Lambda$CDM model.

Khurshudyan, M; Pourhassan, B

2014-01-01

244

Interacting Ghost Dark Energy Models in the Higher Dimensional Cosmology  

CERN Document Server

We investigate interacting ghost dark energy models in higher dimensional cosmology. We attempt to model dark matter within a barotropic fluid with $P_{b}=\\omega(t)_{b}\\rho$. In this work we consider four different models based on choosing equation of state parameter and interaction term. We confirm that our models agree with observational data.

Sadeghi, J; Movsisyan, A; Farahani, H

2014-01-01

245

?-? interaction energy in sub(??)_6He and OBE potentials  

International Nuclear Information System (INIS)

In this paper we evaluate the ?-? interaction energy in sub(??)_6He by using OBE ?-? potentials constructed on the basis of the Nijmegen models. The structure of sub(??)_6He was reinvestigated by solving the ? + ? + ? three-body equation, although simple effective interactions were used. (orig./HSI)

1982-06-25

246

Dark mass creation during EWPT via Dark Energy interaction  

Science.gov (United States)

We add Dark Matter-Dark Energy terms with a quintessence field interacting with a Dark Matter field to a Minimal Supersymmetry Model of the Electroweak (MSSM EW) Lagrangian previously used to calculate the magnetic field created during the Electroweak Phase Transition (EWPT). From the expectation value of the quintessence field, we estimate the Dark Matter mass for parameters used in previous work on Dark Matter-Dark Energy interactions.

Kisslinger, Leonard S.; Casper, Steven

2014-04-01

247

Impact parameters of inelastic hadron interaction at high energies  

International Nuclear Information System (INIS)

The expression for impact parameters of inelastic hadron-hadron interaction with the defined number of charged particles in the final state is obtained from the absorptive model. The model satisfy the unitary condition in the direct reaction channel. The impact parameters of the inelastic pp interaction at ISR energies are calculated. It is found that the impact parameters of multiple production processes decrease with multiplicity growth and at fixed multiplicity they increase with energy

1978-01-01

248

Calculations of Potential Energy Surfaces Using Monte Carlo Configuration Interaction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We apply the method of Monte Carlo configuration interaction (MCCI) to calculate ground-state potential energy curves for a range of small molecules and compare the results with full configuration interaction. We show that the MCCI potential energy curve can be calculated to relatively good accuracy, as quantified using the non-parallelity error, using only a very small fraction of the FCI space. In most cases the potential curve is of better accuracy than its constituent si...

Coe, J. P.; Taylor, D. J.; Paterson, M. J.

2012-01-01

249

Interacting ghost dark energy in Brans-Dicke theory  

International Nuclear Information System (INIS)

We investigate the QCD ghost model of dark energy in the framework of Brans-Dicke cosmology. First, we study the non-interacting ghost dark energy in a flat Brans-Dicke theory. In this case we obtain the equation of state and the deceleration parameters and a differential equation governing the evolution of ghost energy density. Interestingly enough, we find that the equation of state parameter of the non-interacting ghost dark energy can cross the phantom line (wD=-1) provided the parameters of the model are chosen suitably. Then, we generalize the study to the interacting ghost dark energy in both flat and non-flat Brans-Dicke framework and find out that the transition of wD to phantom regime can be more easily achieved for than when resort to the Einstein field equations is made.

2011-11-30

250

Interacting Ghost Dark Energy in Brans-Dicke Theory  

CERN Multimedia

We investigate the QCD ghost model of dark energy in the framework of Brans-Dicke cosmology. First, we study the non-interacting ghost dark energy in a flat Brans-Dicke theory. In this case we obtain the EoS and the deceleration parameters and a differential equation governing the evolution of ghost energy density. Interestingly enough, we find that the EoS parameter of the non-interacting ghost dark energy can cross the phantom line ($w_D=-1$) provided the parameters of the model are chosen suitably. Then, we generalize the study to the interacting ghost dark energy in both flat and non-flat Brans-Dicke framework and find out that the transition of $w_D$ to phantom regime can be more easily achieved for than when resort to the Einstein field equations is made.

Ebrahimi, Esmaeil

2011-01-01

251

Protein-Protein Interaction Analysis by Docking  

Directory of Open Access Journals (Sweden)

Full Text Available Based on a protein-protein docking approach we have developed a procedure to verify or falsify protein-protein interactions that were proposed by other methods such as yeast-2-hybrid assays. Our method currently utilizes intermolecular energies but can be expanded to incorporate additional terms such as amino acid based pair-potentials. We show some early results that demonstrate the general applicability of our approach.

Stephan Ederer

2009-03-01

252

Hadronic interactions and cosmic rays at ultra high energies  

Directory of Open Access Journals (Sweden)

Full Text Available Observations of ultra high energy cosmic rays allow in principle to obtain information about the properties of hadronic interactions in an energy range not accessible with particle accelerators. This task is however complicated by the fact that the composition of the primary CR is not known and must be estimated from the same data set. Solving the ambiguity between composition and hadronic interaction modeling is a central problem for UHECR observations. Recently the Pierre Auger collaboration has presented an estimate of the p–air interaction length at a laboratory energy E0 ? 1018.24?eV. The interaction length is inferred from the shape of the tail of the Xmax distribution of the observed showers, following a method pioneered by the Fly's Eye group. In this work we want to analyse critically this method, and discuss its potential for further studies.

Lipari Paolo

2013-06-01

253

Energy Centroids in the presence of random interactions  

CERN Document Server

In this paper we study energy centroids such as those with fixed spin and isospin, those with fixed irreducible representations for bosons, in the presence of random two-body and/or three-body interactions. Our results show that regularities of energy centroids of fixed spin states reported in earlier works are more robust than expected.

Zhao, Y M; Yoshida, N; Ogawa, K; Yoshinaga, N; Kota, V K B

2005-01-01

254

Phonon Contribution to the Free Energy of Interacting Adatom Pairs.  

Science.gov (United States)

The free energy due to the interaction through the crystal phonon field of two identical atoms adsorbed on a (100) surface of a simple cubic monatomic lattice is studied within the framework of the Montroll-Potts model. The zero-point energy of interactio...

A. A. Maradudin L. Dobrzynski S. L. Cunningham

1972-01-01

255

Strong interactions studies with medium energy probes  

International Nuclear Information System (INIS)

This report discusses work on: charmonium spectroscopy; proton form- factor in the time-like region; proton-antiproton forward scattering; QCD scaling laws; light quark spectroscopy; high resolutions electron scattering; quasi-free electron scattering; and low energy pion double charge exchange

1992-01-01

256

Interactive graphical object-oriented energy modeling and optimization  

Energy Technology Data Exchange (ETDEWEB)

EHTO is an interactive graphical environment for management of energy production and trade. It allows defining and configuring a complete energy system including production units, purchase and sales agreements, and energy balances graphically. A general mathematical modeling and optimization system based on decomposition techniques is embedded to the system, allowing immediate interactive planning, simulation and optimization. The system can be used both for long term off-line computations and for medium to short term on-line computation. The system is implemented in C++ using the graphical NEXUS application development framework. 14 refs, 4 figs, 1 tab

Lahdelma, R. [Jyvaeskylae Univ. (Finland); Makkonen, S. [Process Vision Ltd., Espoo (Finland)

1996-11-01

257

Self-energies and the interactions of particles with surfaces  

Energy Technology Data Exchange (ETDEWEB)

We have in this paper reviewed the method of treating many-body problems by means of an effective interaction self-energy. We have developed an alternatvie approach to the self-energy which is simpler and more straight-forward than standard methods, and we have illustrated its use with two examples of a charge interacting with a metal surface. In each case the self-energy produces the classical image potential together with corrections due to quantum mechanical effects. This method has also been successfully applied to the problem of an atom interacting with a surface. Corrections to the Van der Waals dispersion force are obtained, and via the non-conservative imaginary parts to /summation//sub i/(z) we discuss transition rates and energy exchange. 14 refs., 1 fig.

Manson, J.R.; Ritchie, R.H.; Echenique, P.M.; Gras-Marti, A.

1987-01-01

258

Interacting dark sector with variable vacuum energy  

CERN Document Server

We examine a cosmological scenario where dark matter is coupled to a variable vacuum energy while baryons and photons are two decoupled components for a spatially flat Friedmann-Robertson-Walker spacetime. We apply the $\\chi^{2}$ method to the updated observational Hubble data for constraining the cosmological parameters and analyze the amount of dark energy in the radiation era. We show that our model fulfills the severe bound of $\\Omega_{x}(z\\simeq 1100)<0.009$ at the $2\\sigma$ level, so it is consistent with the recent analysis that includes cosmic microwave background anisotropy measurements from the Planck survey, the Atacama Cosmology Telescope, and the South Pole Telescope along with the future constraints achievable by the Euclid and CMBPol experiments, and fulfills the stringent bound $\\Omega_{x}(z\\simeq 10^{10})<0.04$ at the $2\\sigma$ level in the big-bang nucleosynthesis epoch.

Chimento, Luis P; García, Iván E Sánchez

2013-01-01

259

Interactive Joint Transfer of Energy and Information  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In some communication networks, such as passive RFID systems, the energy used to transfer information between a sender and a recipient can be reused for successive communication tasks. In fact, from known results in physics, any system that exchanges information via the transfer of given physical resources, such as radio waves, particles and qubits, can conceivably reuse, at least part, of the received resources. This paper aims at illustrating some of the new challenges that arise in the des...

Popovski, Petar; Fouladgar, A. M.; Simeone, Osvaldo

2013-01-01

260

Pion-nucleon interaction at low energy  

Energy Technology Data Exchange (ETDEWEB)

The ..pi../sup -/p ..-->.. ..gamma..n and ..pi../sup -/p ..-->.. ..pi../sup 0/n reactions were studied for laboratory pion kinetic energies of 50, 66, 80, 95, 110, and 125 MeV at 9 angles between 30/sup 0/ and 140/sup 0/, using a large NaI(T1) detector, TINA. The results are much more accurate than previous data. The radiative capture differential cross-sections are compared with previous data and with several calculations and will specify more precisely the isoscalar amplitudes in multipole analyses. They are consistent with earlier data and confirm the principle of detailed balance, but indicate that the theoretical calculations cannot reproduce the nucleon data adequately below resonance. The charge exchange differential cross-sections are obtained by unfolding the energy spectra of the ..pi../sup 0/ ..gamma..-ray decay, and agree with the Karlsruhe and VPI phase-shift analyses. Pion-nucleon phase-shifts and scattering lengths are calculated and the results are in good agreement with data from the elastic scattering channels and support isospin invariance in this energy region.

Bagheri, A.

1986-01-01

 
 
 
 
261

Low-energy antiproton-neon interaction  

International Nuclear Information System (INIS)

By means of a streamer chamber exposed to the LEAR antiproton beams, the total reaction cross sections, the charged-prong multiplicity distributions and lower limits for the production of negative pions and Ksub(s)0 in the anti p-Ne interaction were measured at 19.6, 48.7 and 179.6 MeV. Annihilation was found to be dominant over all other non-elastic anti p-Ne processes. An analysis of Ne and other nuclei data in the frame of the Glauber theory allowed us to determine the ratio between the anti p-n and the anti p-p cross sections. An analysis in the light of INC model predictions allowed us to show up events which can be interpreted as annihilations having occurred deeply inside the nuclei. (orig.)

1986-05-05

262

Interacting agegraphic dark energy models in non-flat universe  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A so-called "agegraphic dark energy" was recently proposed to explain the dark energy-dominated universe. In this Letter, we generalize the agegraphic dark energy models to the universe with spatial curvature in the presence of interaction between dark matter and dark energy. We show that these models can accommodate $w_D = -1 $ crossing for the equation of state of dark energy. In the limiting case of a flat universe, i.e. $k = 0$, all previous results of agegraphic dark en...

Sheykhi, Ahmad

2009-01-01

263

Electron-gas plus damped-dispersion model for intermolecular forces: the rare-gas and H2-He, H2-Ne, and H2-Ar potentials  

International Nuclear Information System (INIS)

The modified Gordon-Kim (MGK) electron-gas model for the calculation of the short-range repulsive interactions between closed-shell atoms and molecules is used with a damped-dispersion term of a form suggested by Hepburn et al. to calculate the intermolecular potentials between the rare-gas atoms and H2-He, H2-Ne, and H2-Ar. The damping function for the dispersion energies is found by comparison with the experimental Ar-Ar potential and is then used without change for all other interactions. Except for interactions involving Ne atoms, the results for the atom-atom interactions are uniformly quite good, with an average deviation from experiment in the position of the minimum (neglecting those involving Ne atoms) of only 0.7%. Both the radical V0(r) and anisotropic V2(r) terms of the atom-molecule results are compared with experiment. The calculated V0(r) potentials for He-H2 and Ar-H2 show close agreement with experiment, though the V2 terms are less well determined. All interactions involving Ne atoms are too repulsive. The errors in the potentials involving Ne atoms are attributed to errors in the treatment of the exchange energy in the MGK model. 29 references, 11 figures, 5 tables

1984-09-13

264

Molecular mechanisms of action of film gas analyzer, sensitive to amines. 3. Iodine and dithizone part in processes of amine interaction with film element: polyvinyl alcohol-I_2-dithizone  

International Nuclear Information System (INIS)

CNDO semiempirical method with modified potential of atomic core interaction is used to study character of interaction of the complex polyvinyl alcohol-I_2 with dithizone and diethyl amine molecules. Different types of coordination of dithizne molecule to polyvinyl alcohol fragment are considered, equilibrium intermolecular distances are found and energy characteristics of the systems considered are obtained

1985-09-01

265

Modeling dark energy through an Ising fluid with network interactions  

CERN Multimedia

We show that the dark energy effects can be modeled by using an \\emph{Ising perfect fluid} with network interactions, whose low redshift equation of state, i.e. $\\omega_0$, becomes $\\omega_0=-1$ as in the $\\Lambda$CDM model. In our picture, dark energy is characterized by a barotropic fluid on a lattice in the equilibrium configuration. Thus, mimicking the spin interaction by replacing the spin variable with an occupational number, the pressure naturally becomes negative. We find that the corresponding equation of state mimics the effects of a variable dark energy term, whose limiting case reduces to the cosmological constant $\\Lambda$. This permits us to avoid the introduction of a vacuum energy as dark energy source by hand, alleviating the coincidence and fine tuning problems. We find fairly good cosmological constraints, by performing three tests with supernovae Ia, baryonic acoustic oscillation and cosmic microwave background measurements. Finally, we perform the AIC and BIC selection criteria, showing t...

Luongo, Orlando

2013-01-01

266

Empirical proton-neutron interaction energies and nuclear structure  

International Nuclear Information System (INIS)

Empirical proton-neutron (p-n) interaction energies are extracted for all even-even nuclei with well-known binding energies using a simple double difference equation. Three features are disclosed: a systematic decrease of p-n interaction strengths (excepting N=Z nuclei) with increasing A, large interaction strengths for N=Z nuclei, and microstructure in doubly magic and deformed regions. Shell model calculations are used to explain the behavior of N=Z and other nuclei in the sd shell. Arguments based on orbit occupancy are introduced to explain microstructure effects in heavier nuclei and are given quantitative support by simple microscopic Nilsson and Shell Model calculations. The analysis sheds light on the relative roles of monopole and quadrupole components of the p-n interaction in determining nuclear structure. 19 refs., 5 figs

1990-09-09

267

Intermolecular proton transfer in anionic complexes of uracil with alcohols  

Energy Technology Data Exchange (ETDEWEB)

A series of eighteen alcohols (ROH) has been designed with an enthalpy of deprotonation (HDP) in a range of 13.8-16.3 eV. The effects of excess electron attachment to the binary alcohol-uracil (ROH…U) complexes have been studied at the density functional level with a B3LYP exchange-correlation functional and at the second order Møller-Plesset perturbation theory level. The photoelectron spectra of anionic complexes of uracil with three alcohols (ethanol, 2,2,3,3,3-pentafluoroethanol and 1,1,1,3,3,3-hexafluoro-2-propanol) have been measured with 2.54 eV photons. For ROHs with deprotonation enthalpies larger than 14.8 eV only the ROH...U- minimum exists on the potential energy surface of the anionic complex. For alcohols with deprotonation enthalpies in a range of 14.3-14.8 eV two minima might exist on the anionic potential energy surface, which correspond to the RO-…HU. and ROH...U- structures. For ROHs with deprotonation enthalpies smaller than 14.3 eV, the excess electron attachment to the ROH…U complex always induces a barrier-free proton transfer from the hydroxyl group of ROH to the O8 atom of U, with the product being RO-…HU.. A driving force for the intermolecular proton transfer is to stabilize the excess negative charge localized on a ?* orbital of uracil. Therefore, these complexes with proton transferred to the anionic uracil are characterized by larger values of electron vertical detachment energy (VDE). The values of VDE for anionic complexes span a range from 1.0 to 2.3 eV and roughly correlate with the acidity of alcohols. However, there is a gap of ~0.5 eV in the values of VDE, which separates the two families, ROH...U- and RO-…HU., of anionic complexes. The energy of stabilization for the anionic complexes spans a range from 0.6 to 1.7 eV and roughly correlates with the acidity of alcohols. The measured photoelectron spectra are in good agreement with the theoretical predictions.

Haranczyk, Maciej; Rak, Janusz; Gutowski, Maciej S.; Radisic, Dunja; Stokes, Sarah T.; Bowen, Kit H.

2005-07-14

268

Kaon nucleon interaction at intermediate energies  

International Nuclear Information System (INIS)

The kaon nucleon system in I = 0 and I = 1 states is studied in terms of a model lagrangian containing Yukawa terms and contact terms which represent effective short range forces in both isospin states. We compute all Feynman diagrams contributions up to the fourth order and use the Pade approximants method to construct S matrix elements satisfying unitarity. Using values already determined for the Yukawa coupling constants g sub(N?K) and g sub(N?K) and the well-known value for the scattering length in I = 1, it remains as the only free parameter in the model the strength of the contact term in I = 0. Results are discussed and compared with available experimental data at low and intermediate energies, for K"0P ? K"+n, K"+p ? K"+p and K"+d ? K"0pp processes. (Author)

1980-01-01

269

Mutually interacting Tachyon dark energy with variable $G$ and $\\Lambda$  

CERN Document Server

In this paper we consider Tachyonic scalar field as dark energy with interaction between components in the case of variable $G$ and $\\Lambda$. We assume a flat Universe with specific form of scale factor and study cosmological parameters numerically and graphically. Statefinder analysis also performed as well. In the special choice of interaction parameters we succeed to obtain analytical expression of densities. We find that our model will be stable in the late stage but there is an instability at the early Universe.

Hakobyan, J Sadeghi M Khurshudyan M

2013-01-01

270

Neutral current neutrino-nucleus interactions at high energies  

CERN Document Server

We present a QCD analysis of the neutral current neutrino-nucleus interaction at the small-x region using the color dipole formalism. This phenomenological approach is quite successful in describing experimental results in deep inelastic ep scattering and charged current neutrino-nucleus interactions at high energies. We present theoretical predictions for the relevant structure functions and the corresponding implications for the total NC neutrino cross section.

Ducati, M B Gay; Machado, M V T

2008-01-01

271

On the Casimir Energy of Frequency Dependent Interactions  

CERN Document Server

Vacuum polarization (or Casimir) energies can be straightforwardly computed from scattering data for static field configurations whose interactions with the fluctuating field are frequency independent. In effective theories, however,such interactions are typically frequency dependent. As a consequence, the relationship between scattering data and the Green's function is modified, which may or may not induce additional contributions to the vacuum polarization energy. We discuss several examples that naturally include frequency dependent interactions: (i) scalar electrodynamics with a static background potential, (ii) an effective theory that emerges from integrating out a heavy degree of freedom, and (iii) quantum electrodynamics coupled to a frequency dependent dielectric material. In the latter case, we argue that introducing dissipation as required by the Kramers-Kronig relations requires the consideration of the Casimir energy within a statistical mechanics formalism, while in the absence of dissipation we...

Graham, N; Weigel, H

2014-01-01

272

Impact of Electron-Electron Cusp on Configuration Interaction Energies  

CERN Document Server

The effect of the electron-electron cusp on the convergence of configuration interaction (CI) wave functions is examined. By analogy with the pseudopotential approach for electron-ion interactions, an effective electron-electron interaction is developed which closely reproduces the scattering of the Coulomb interaction but is smooth and finite at zero electron-electron separation. The exact many-electron wave function for this smooth effective interaction has no cusp at zero electron-electron separation. We perform CI and quantum Monte Carlo calculations for He and Be atoms, both with the Coulomb electron-electron interaction and with the smooth effective electron-electron interaction. We find that convergence of the CI expansion of the wave function for the smooth electron-electron interaction is not significantly improved compared with that for the divergent Coulomb interaction for energy differences on the order of 1 mHartree. This shows that, contrary to popular belief, description of the electron-electro...

Prendergast, D; Filippi, C; Fahy, S; Greer, J C; Prendergast, David; Filippi, Claudia; Fahy, Stephen

2001-01-01

273

Intermolecular Hydrogen Transfer in Isobutane Hydrate  

Directory of Open Access Journals (Sweden)

Full Text Available Electron spin resonance (ESR spectra of butyl radicals induced with ?-ray irradiation in the simple isobutane (2-methylpropane hydrate (prepared with deuterated water were investigated. Isothermal annealing results of the ?-ray-irradiated isobutane hydrate reveal that the isobutyl radical in a large cage withdraws a hydrogen atom from the isobutane molecule through shared hexagonal-faces of adjacent large cages. During this “hydrogen picking” process, the isobutyl radical is apparently transformed into a tert-butyl radical, while the sum of isobutyl and tert-butyl radicals remains constant. The apparent transformation from isobutyl to tert-butyl radicals is an irreversible first-order reaction and the activation energy was estimated to be 35 ± 3 kJ/mol, which was in agreement with the activation energy (39 ± 5 kJ/mol of hydrogen picking in the ?-ray-irradiated propane hydrate with deuterated water.

Takeshi Sugahara

2012-05-01

274

Interacting Dark Matter and Dark Energy  

CERN Multimedia

We discuss models for the cosmological dark sector in which the energy density of a scalar field approximates Einstein's cosmological constant and the scalar field value determines the dark matter particle mass by a Yukawa coupling. A model with one dark matter family can be adjusted so the observational constraints on the cosmological parameters are close to but different from what is predicted by the Lambda CDM model. This may be a useful aid to judging how tightly the cosmological parameters are constrained by the new generation of cosmological tests that depend on the theory of structure formation. In a model with two families of dark matter particles the scalar field may be locked to near zero mass for one family. This can suppress the long-range scalar force in the dark sector and eliminate evolution of the effective cosmological constant and the mass of the nonrelativistic dark matter particles, making the model close to Lambda CDM, until the particle number density becomes low enough to allow the scal...

Farrar, G R; Farrar, Glennys R.

2004-01-01

275

Covariantizing the interaction between dark energy and dark matter  

CERN Document Server

Coupling dark energy and dark matter through an effective fluid description is a very common procedure in cosmology, however it always remains in comoving coordinates in the special FLRW space. We construct a consistent, general, and covariant formulation, where the interaction is a natural implication of the imperfectness of the fluids. This imperfectness makes difficult the final step towards a robust formulation of interacting fluids, namely the construction of a Lagrangian whose variation would give rise to the interacting equations. Nevertheless, we present a formal solution to this problem for a single fluid, through the introduction of an effective metric.

Faraoni, Valerio; Saridakis, Emmanuel N

2014-01-01

276

Semiconductor surface sublimation energies and atom-atom interactions  

Science.gov (United States)

The energy required to remove an atom from semiconductor surfaces is calculated using a Green's-function approach. Contrary to intuition, it is found that, in some cases, less energy is needed to remove an atom from the nearly full surface than from a nearly empty surface. The results are explained in terms of the relative energies of anion and cation dangling bonds, and the charge transfers between them. The deducted effective pair-interaction energies and their effects on surface morphology and growth perfection are discussed.

Krishnamurthy, Srinivasan; Berding, M. A.; Sher, A.; Chen, A.-B.

1990-01-01

277

Constraints on interacting Dark Energy models from galaxy rotation curves  

Science.gov (United States)

Interacting Dark Energy models have been introduced as a possible alternative to the standard ?CDM concordance cosmological scenario in order to ease the fine-tuning problems of the cosmological constant. However, the interaction of the Dark Energy field with other massive particles in the universe induces also an effective modification of structure formation processes, leading to a different dynamical behavior of density perturbations with respect to the standard scenario. In particular, high-resolution N-body simulations have recently shown that also the structural properties of highly nonlinear objects, as e.g. their average concentration at a given mass, could be significantly modified in the presence of an interaction between Dark Energy and Dark Matter. While a constant interaction strength leads to less concentrated density profiles, a steep growth in time of the coupling function has been shown to determine a large increase of halo concentrations over a wide range of masses, including the typical halos hosting luminous spiral galaxies. This determines a substantial worsening of the "cusp-core" tension arising in the standard ?CDM model and provides a direct way to constrain the form of the Dark Energy interaction. In the present paper we make use of the outcomes of some high-resolution N-body simulations of a specific class of interacting Dark Energy models to compare the predicted rotation curves of luminous spiral galaxies forming in these cosmologies against real observational data. Our results show how some specific interacting Dark Energy scenarios featuring a steep growth in time of the coupling function — which are virtually indistinguishable from ?CDM in the background — cannot fit the observed rotation curves of luminous spiral galaxies and can therefore be ruled out only on the basis of dynamical properties of small-scale structures. Our study is a pilot investigation of the effects of a Dark Energy interaction at small scales, and demonstrates how the dynamical properties of visible galaxies can in some cases provide direct constraints on the nature of Dark Energy.

Baldi, Marco; Salucci, Paolo

2012-02-01

278

Interacting Ghost Dark Energy in Non-Flat Universe  

CERN Multimedia

A new dark energy model called "ghost dark energy" was recently suggested to explain the observed accelerating expansion of the universe. This model originates from the Veneziano ghost of QCD. The dark energy density is proportional to Hubble parameter, $\\rho_D=\\alpha H$, where $\\alpha$ is a constant of order $\\Lambda_{\\rm QCD}^3$ and $\\Lambda_{\\rm QCD}\\sim 100 MeV$ is QCD mass scale. In this Letter, we extend the ghost dark energy model to the universe with spatial curvature in the presence of interaction between dark matter and dark energy. We study cosmological implications of this model in detail. In the absence of interaction the equation of state parameter of ghost dark energy is always $w_D > -1 $ and mimics a cosmological constant in the late time, while it is possible to have $w_D < -1 $ provided the interaction is taken into account. When $k = 0$, all previous results of ghost dark energy in flat universe are recovered.

Sheykhi, A

2011-01-01

279

Orientational disorder and the intermolecular potential of FCC C60  

International Nuclear Information System (INIS)

Careful diffraction studies reveal that the orientational distribution of C60 molecules in disordered high-temperature FCC fullerene deviates significantly from random. These studies show that the molecular orientational preferences anticipate the low temperature orientationally ordered phase, help explain the orientational glass behavior noted in this material and provide quantitative estimates of the intermolecular orientational forces at work. (orig.)

1996-04-01

280

Elastic energy of the flux lines in the matter. The interaction energy  

International Nuclear Information System (INIS)

A theoretical treatment of the interaction between the bodies, by using the elastic coupling through the flux lines, is presented. We show that the elastic coupling through the flux lines gives an interaction energy between two superconductor or magnetic pieces, which is inversely proportional to the distance between the two bodies. We extend this concept to the gravitational and electrical interaction. For the electrical interaction one obtains that the statics interaction energy is inversely proportional to the distance between the charges, as in the Coulomb's law, while the oscillatory interaction is inversely proportional to the third power of the distance between the charged particles. This means that at shorter distance an attraction between the two charged particles of the same sign, may appear if the oscillatory energy of interaction is larger than the statics energy of interaction. In addition, the oscillatory interaction appears only as a virtual process. We apply these results to the deuteron and to the electron pairs in superconductors. Also, for the gravitation one obtains that the interaction energy is inversely proportional to the distance between the centers of the two bodies as in Newton's law. (author)

1999-01-01

 
 
 
 
281

Transition of the dark energy equation of state in an interacting holographic dark energy model  

International Nuclear Information System (INIS)

A model of holographic dark energy with an interaction with matter fields has been investigated. Choosing the future event horizon as an IR cutoff, we have shown that the ratio of energy densities can vary with time. With the interaction between the two different constituents of the universe, we observed the evolution of the universe, from early deceleration to late time acceleration. In addition, we have found that such an interacting dark energy model can accommodate a transition of the dark energy from a normal state where wD>-1 to wD<-1 phantom regimes. Implications of interacting dark energy model for the observation of dark energy transition has been discussed

2005-09-29

282

Self-interaction errors in nuclear energy density functionals  

Digital Repository Infrastructure Vision for European Research (DRIVER)

When applied to a single nucleon, nuclear energy density functionals may yield a non-vanishing internal energy thus implying that the nucleon is interacting with itself. It is shown how to avoid this unphysical feature for semi-local phenomenological functionals containing all possible bilinear combinations of local densities and currents up to second order in the derivatives. The method outlined in this Rapid Communication could be easily extended to functionals containing ...

Chamel, N.

2010-01-01

283

The halo mass function in interacting dark energy models  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a detailed investigation of the effects imprinted by a direct interaction between dark energy and cold dark matter particles on the halo mass function of groups and clusters of galaxies. Making use of the public halo catalogues of the codecs simulations, we derive the halo mass function for several different types of coupled dark energy scenarios, based on both the friends-of-friends algorithm and the spherical overdensity halo identification for different values of the overdensity...

Cui, Weiguang; Baldi, Marco; Borgani, Stefano

2012-01-01

284

Distributed energy resources in grid interactive AC microgrids  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Increased penetration of distributed energy resources (DER) and large-scale deployment of renewable energy sources are challenging the entire architecture of traditional power system. Microgrid, featuring higher flexibility and reliability, becomes an attractive candidate for the configuration of future electrical power system. This paper gives an overview of DER units in the grid interactive ac microgrid. The options in structures and control methods of power electronics interfaced DER units...

Wang, Xiongfei; Guerrero, Josep; Chen, Zhe; Blaabjerg, Frede

2010-01-01

285

The vacuum energy of QED with four-fermion interaction  

International Nuclear Information System (INIS)

We consider quantum electrodynamics in the quenched approximation including a four-fermion interaction with coupling constant g. The effective constants ? and g and an ultraviolet cutoff ?, showing a minimum of energy in the (?,g) plane for ? = ?c = ?/3 and g=?. When we go to the continuum limit (? ? ?), keeping finite the dynamical mass, the minimum of energy moves to (? 0,g = 1), which correspond to a point where the theory is trivial. (author). 16 refs, 3 figs

1991-09-18

286

U'(1) Neutrino Interaction at Very Low Energies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A procedure for studying low energy neutrinos processes using hadronic physics ideas is proposed. We describe how the neutrino-neutrino interactions can be modelled using massive gauge theories. The mass of the gauge bosons is created by spontaneous symmetry breaking and we show that relationship between mass, currents and potential gauge is through vector dominance, i.e. $J_\\mu = M^2 A_\\mu$. A tiny charge $U(1)$ for neutrinos is turned on for energies around the temperature...

Gamboa, J.

2014-01-01

287

Integrated Sachs-Wolfe effect in interacting dark energy models  

International Nuclear Information System (INIS)

Models with dark energy decaying into dark matter have been proposed in cosmology to solve the coincidence problem. We study the effect of such coupling on the cosmic microwave background temperature anisotropies. The interaction changes the rate of evolution of the metric potentials and the growth rate of matter density perturbations and modifies the integrated Sachs-Wolfe component of cosmic microwave background temperature anisotropies, enhancing the effect. Cross correlation of galaxy catalogs with cosmic microwave background maps provides a model-independent test to constrain the interaction. We particularize our analysis for a specific interacting model and show that galaxy catalogs with median redshifts zm=0.1-0.9 can rule out models with an interaction parameter strength of c2?0.1 better than 99.95% confidence level. Values of c2?0.01 are compatible with the data and may account for the possible discrepancy between the fraction of dark energy derived from Wilkinson microwave anisotropy probe 3 yr data and the fraction obtained from the integrated Sachs-Wolfe effect. Measuring the fraction of dark energy by these two methods could provide evidence of an interaction

2008-05-15

288

Effective dark energy equation of state in interacting dark energy models  

Energy Technology Data Exchange (ETDEWEB)

In models where dark matter and dark energy interact non-minimally, the total amount of matter in a fixed comoving volume may vary from the time of recombination to the present time due to energy transfer between the two components. This implies that, in interacting dark energy models, the fractional matter density estimated using the cosmic microwave background assuming no interaction between dark matter and dark energy will in general be shifted with respect to its true value. This may result in an incorrect determination of the equation of state of dark energy if the interaction between dark matter and dark energy is not properly accounted for, even if the evolution of the Hubble parameter as a function of redshift is known with arbitrary precision. In this Letter we find an exact expression, as well as a simple analytical approximation, for the evolution of the effective equation of state of dark energy, assuming that the energy transfer rate between dark matter and dark energy is described by a simple two-parameter model. We also provide analytical examples where non-phantom interacting dark energy models mimic the background evolution and primary cosmic microwave background anisotropies of phantom dark energy models.

Avelino, P.P., E-mail: ppavelin@fc.up.pt [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Silva, H.M.R. da, E-mail: hilberto.silva@gmail.com [Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)

2012-07-24

289

Wormhole solutions supported by interacting dark matter and dark energy  

CERN Document Server

We show that the presence of a nonminimal interaction between dark matter and dark energy may lead to a violation of the null energy condition and to the formation of a configuration with nontrivial topology (a wormhole). In this it is assumed that both dark matter and dark energy satisfy the null energy condition, a violation of which takes place only in the inner high-density regions of the configuration. This is achieved by assuming that, in a high-density environment, a nonminimal coupling function changes its sign in comparison with the case where dark matter and dark energy have relatively low densities which are typical for a cosmological background. For this case, we find regular static, spherically symmetric solutions describing wormholes supported by dark matter nonminimally coupled to dark energy in the form of a quintessence scalar field.

Folomeev, Vladimir

2013-01-01

290

Polarization phenomena in electromagnetic interactions at intermediate energies  

International Nuclear Information System (INIS)

Recent results of polarization measurements in electromagnetic interactions at intermediate energies are discussed. Prospects of polarization experiments at the new CW electron accelerators, as well as on upgraded older machines are outlined. It is concluded that polarization experiments will play a very important role in the study of the structure of the nucleon and of light nuclei. 72 refs

1990-07-09

291

A new interpretation of high energy proton-nucleus interactions  

International Nuclear Information System (INIS)

The correlation between the properties of the heavy prong and the shower particle distributions from high energy proton-nucleus interactions are considered in a phenomenological model in which the number of collisions between the impinging proton and the nucleons inside the nucleus is the major parameter. (Auth.)

1975-08-15

292

Interacting Energy Components and Observational H(z) Data  

CERN Document Server

In this note, we extend our previous work [Phys. Lett. B 644, 7 (2007), astro-ph/0609597], and compare eleven interacting dark energy models with different couplings to the observational $H(z)$ data. However, none of these models is better than the simplest $\\Lambda$CDM model. This implies that either more exotic couplings are needed in the cosmological models with interaction between dark energy and dust matter, or there is no interaction at all. In fact, as shown in our previous work, the observational $H(z)$ data favors the models which have an oscillating feature for both $H(z)$ and effective equation-of-state parameter (EoS), with the effective EoS crossing -1 around redshift $z\\sim 1.5$. Therefore, other physical mechanisms are needed to produce an oscillating feature for $H(z)$ which can also fit the observational $H(z)$ data fairly well.

Wei, Hao

2007-01-01

293

The interaction between dark energy and dark matter  

International Nuclear Information System (INIS)

In this review we first present a general formalism to study the growth of dark matter perturbations in the presence of interactions between dark matter(DM) and dark energy(DE). We also study the signature of such interaction on the temperature anisotropies of the large scale cosmic microwave background (CMB). We find that the effect of such interaction has significant signature on both the growth of dark matter structure and the late Integrated Sachs Wolfe effect(ISW). We further discuss the potential possibility to detect the coupling by cross-correlating CMB maps with tracers of the large scale structure. We finally confront this interacting model with WMAP 5-year data as well as other data sets. We find that in the 1? range, the constrained coupling between dark sectors can solve the coincidence problem.

2010-04-01

294

Cosmological evolution of interacting dark energy in Lorentz violation  

International Nuclear Information System (INIS)

The cosmological evolution of an interacting scalar-field model in which the scalar field interacts with dark matter, radiation, and baryons via Lorentz violation is investigated. We propose a model of interaction through the effective coupling, anti ?. Using dynamical system analysis, we study the linear dynamics of an interacting model and show that the dynamics of critical points are completely controlled by two parameters. Some results can be mentioned as follows. Firstly, the sequence of radiation, the dark matter, and the scalar-field dark energy exist and baryons are subdominant. Secondly, the model also allows for the possibility of having a universe in the phantom phase with constant potential. Thirdly, the effective gravitational constant varies with respect to time through anti ?. In particular, we consider the simple case where anti ? has a quadratic form and has a good agreement with the modified ?CDM and quintessence models. Finally, we also calculate the first post-Newtonian parameters for our model. (orig.)

2009-10-01

295

Inclusive. delta. /sup + +/ in pp interactions at ISR energies  

Energy Technology Data Exchange (ETDEWEB)

Inclusive cross sections for ..delta../sup + +/ production in pp interactions at different ISR energies are presented. The differential cross section dsigma/dx for ..delta../sup + +/ production is found to be approximately independent of Feynman x. No strong energy dependence is seen over the ISR energy range. The topological cross sections of ..delta../sup + +/ at ..sqrt..s=62 GeV show an appreciable contribution from non-diffractive production mechanisms. An upper limit for the ..delta../sup 0/ production cross section is determined.

Breakstone, A.; Crawley, H.B.; Firestone, A.; Gorbics, M.; Lamsa, J.W.; Meyer, W.T.; Campanini, R.; Dallavalle, G.M.; Rimondi, F.; Doroba, K.

1984-01-01

296

Color sextet quarks and new high-energy interactions  

International Nuclear Information System (INIS)

We review the implications of adding a flavor doublet of color sextet quarks to QCD. Theoretical attractions include -- ''minimal'' dynamical symmetry breaking of the electroweak interaction, solution of the Strong CP problem via the ''heavy axion'' ?_6, and Critical Pomeron Scaling at asymptotic energies. Related experimental phenomena, which there may be evidence for, include -- production of the ?_6 at LEP, large cross-sections for W"+W"- and Z"oZ"o pairs and very high energy jets in hadron colliders, and a hadronic threshold above which high-energy ''exotic'' diffractive processes appear in Cosmic Ray events

1992-06-21

297

Schematic potential energy for interaction between isobutene and zeolite mordenite  

International Nuclear Information System (INIS)

A schematic representation of the potential energy for the interaction between isobutene and H mordenite was presented by using eight different positions (P1-P8) of C1 or C2 atoms located in front of the acid hydrogen (H+). In all cases a ? complex was formed yielding different values of the adsorption energy. In some cases of the adsorption point in P1-P8 the frontier orbitals are shown. The P8 position exhibits the highest value obtained for the adsorption energy, where the C1 atom is in front of the H+. Calculations were of all electron type employing HF/6-31G**

2004-06-09

298

Interactions of quarks and gluons with nuclei at intermediate energies  

Energy Technology Data Exchange (ETDEWEB)

Some processes involving the interaction of medium energy quarks and gluons with nuclear matter are described. Possible mechanisms for the A-dependence of the energy loss of leading protons produced in proton-nucleus collisions are given, and an experiment which may help to distinguish these mechanisms is described. A possible color transparency experiment at CEBAF is described. Experiments to measure energy loss of quarks in nuclear matter and the formation time of hadrons are discussed along with the possibilities of measuring {sigma}{sub J}/{psi} and {sigma}{sub {psi}{prime}} at CEBAF.

Mueller, A.H. [Columbia Univ., New York, NY (United States)

1994-04-01

299

Energy deposition by nuclear interactions in microscopic volumes  

Energy Technology Data Exchange (ETDEWEB)

A computer simulation has been developed which calculates the energy deposited in a small sensitive volume by nuclear interactions. A Monte Carlo approach is used. The energy deposited by the incident particles, by the cascade and evaporation particles, and by the residual nuclei from the interactions is calculated. The small sensitive volume can be embedded in a large volume, and energy deposited in the sensitive volume by interactions taking place in the large volume can be calculated. The nuclear model used in the simulation is shown to be in agreement with experiment and with other models. The predicted energy deposition spectra are shown to be in good agreement with results obtained by exposing silicon surface barrier detectors to proton beams at the Harvard Cyclotron. The recoiling residual nuclei were found to play a major role in the energy deposition in thin detectors. The simulation can be used to predict the soft error rate of microelectronic devices exposed to protons or neutrons. It will be particularly useful for devices flown in space, where protons are present in the radiation belts and are the most abundant component of the cosmic rays.

Farrell, G.E.

1983-01-01

300

Interacting generalized ghost dark energy in non-flat universe  

CERN Document Server

We investigate the generalized QCD ghost model of dark energy in the framework of Einstein gravity. First, we study the non-interacting generalized ghost dark energy in a flat FRW background. We obtain the equation of state parameter, $w_D=p/\\rho$, the deceleration parameter, and the evolution equation of the generalized ghost dark energy. We find that, in this case, $w_D$ cannot cross the phantom line ($w_D>-1$) and eventually the universe approaches a de-Sitter phase of expansion $(w_D\\rightarrow-1)$. Then, we extend the study to the interacting ghost dark energy in both flat and non-flat FRW universe. We find out that the equation of state parameter of the interacting generalized ghost dark energy can cross the phantom line ($w_D<-1$) provided the parameters of the model are chosen suitably. We also discuss the values of the deceleration parameter in all cases and present a numerical evaluation of this parameter in different phases of the universe expansion.

Ebrahimi, Esmaeil

2012-01-01

 
 
 
 
301

Holographic dark energy linearly interacting with dark matter  

CERN Document Server

We investigate a spatially flat Friedmann-Robertson-Walker (FRW) cosmological model with cold dark matter coupled to a modified holographic Ricci dark energy through a general interaction term linear in the energy densities of dark matter and dark energy, the total energy density and its derivative. Using the statistical method of $\\chi^2$-function for the Hubble data, we obtain $H_0=73.6$km/sMpc, $\\omega_s=-0.842$ for the asymptotic equation of state and $ z_{acc}= 0.89 $. The estimated values of $\\Omega_{c0}$ which fulfill the current observational bounds corresponds to a dark energy density varying in the range $0.25R < \\ro_x < 0.27R$.

Chimento, Luis P; Richarte, Martín G

2012-01-01

302

Interactive Energy Planning : towards a sound and effective planning praxis  

DEFF Research Database (Denmark)

Though it is being questioned whether planning theory should be fitted into neat typologies, some have described evolving planning theory as a journey away from ethnocentrism, through the lands of rationalism, pragmatism, socio-ecological idealism, political-economic mobilization, currently anchoring along the shores of the land of communications and collaboration. Whether or not a particular typology is applicable, theory and praxis are establishing standpoints, which strengthens our understanding of the planning complex, and which should inspire improved energy planning methodologies and tools. This paper presents an â??Interactive Energy Planningâ? framework, which is intended to support interactivity in planning, building on important theoretical and experimental advances in planning. In particular, the paper explores the potential significance of allowing a critical perspective on context analysis and problem-orientation to define the course of the planning process, and deploying value-rational planning tools primarily as a platform for interactivity. The focus on interactivity in energy planning will allow contemporary government planners, consultants, researchers, and organizational managers more effectively to address important technical and economic problems.

Blarke, Morten Boje

2006-01-01

303

Constraints on interacting dark energy models from galaxy Rotation Curves  

CERN Document Server

[Abridged] High-resolution N-body simulations have recently shown that the structural properties of highly nonlinear cosmic structures, as e.g. their average concentration at a given mass, could be significantly modified in the presence of an interaction between Dark Energy and Dark Matter. While a constant interaction strength leads to less concentrated density profiles, a steep growth in time of the coupling function has been shown to determine a large increase of halo concentrations over a wide range of masses, including the typical halos hosting luminous spiral galaxies. This determines a substantial worsening of the "cusp-core" tension arising in the standard $\\Lambda $CDM model and provides a direct way to constrain the form of the Dark Energy interaction. In the present paper we make use of the outcomes of some high-resolution N-body simulations of a specific class of interacting Dark Energy models to compare the predicted rotation curves of luminous spiral galaxies forming in these cosmologies against...

Baldi, Marco

2011-01-01

304

Reconstructing the interaction term between dark matter and dark energy  

CERN Document Server

We apply a parametric reconstruction method to a homogeneous, isotropic and spatially flat Friedmann-Robertson-Walker (FRW) cosmological model filled of a fluid of dark energy (DE) with constant equation of state parameter interacting with dark matter (DM). The reconstruction method is based on expansions of the general interaction term and the relevant cosmological variables in terms of Chebyshev polynomials which form a complete set orthonormal functions. This interaction term describes an exchange of energy flow between the DE and DM within dark sector. To show how the method works we do the reconstruction of the interaction function expanding it in terms of only the first three Chebyshev polynomials and obtain the best estimation for the coefficients of the expansion as well as for the DE equation of the state constant parameter w using the type Ia Supernova SCP Union data set (307 SNe-Ia). The preliminary reconstruction shows that in the best scenario there is an energy transfer from DM to DE which worse...

Cueva, Freddy

2010-01-01

305

Intermolecular hydrogen bond complexes by in situ charge transfer complexation of o-tolidine with picric and chloranilic acids  

Science.gov (United States)

A two new charge transfer complexes formed from the interactions between o-tolidine (o-TOL) and picric (PA) or chloranilic (CA) acids, with the compositions, [(o-TOL)(PA) 2] and [(o-TOL)(CA) 2] have been prepared. The 13C NMR, 1H NMR, 1H-Cosy, and IR show that the charge-transfer chelation occurs via the formation of chain structures O-H⋯N intermolecular hydrogen bond between 2NH 2 groups of o-TOL molecule and OH group in each PA or CA units. Photometric titration measurements concerning the two reactions in methanol were performed and the measurements show that the donor-acceptor molar ratio was found to be 1:2 using the modified Benesi-Hildebrand equation. The spectroscopic data were discussed in terms of formation constant, molar extinction coefficient, oscillator strength, dipole moment, standard free energy, and ionization potential. Thermal behavior of both charge transfer complexes showed that the complexes were more stable than their parents. The thermodynamic parameters were estimated from the differential thermogravimetric curves. The results indicated that the formation of molecular charge transfer complexes is spontaneous and endothermic.

Refat, Moamen S.; Saad, Hosam A.; Adam, Abdel Majid A.

2011-08-01

306

Low-Energy $KN$ Interactions at a $\\phi$-Factory  

CERN Document Server

The paper is the written version of a talk presented at the "VIIth Winter School of Hadronic Physics", held in Folgaria (Trento), Italy, February 10--15, 1992. We intend to illustrate in this lecture the possibilities opening up at machines planned for the nineties for low--energy kaon--nucleon interactions, keeping the focus on the theoretical problems they should help to solve. We shall deal here only with the $\\phi$--factory DA$\\Phi$NE$^1$ and consider, for brevity, interactions with light, gaseous targets, using gaseous $H_2$ as a benchmark for which to estimate the rates to be expected in a typical apparatus.

Gensini, P M

1992-01-01

307

Sustainable Interactions: Studies in the Design of Energy Awareness Artefacts  

Energy Technology Data Exchange (ETDEWEB)

This thesis presents a collection of experimental designs that approach the problem of growing electricity consumption in homes. From the perspective of design, the intention has been to critically explore the design space of energy awareness artefacts to reinstate awareness of energy use in everyday practice. The design experiments were used as vehicles for thinking about the relationship between physical form, interaction, and social practice. The rationale behind the concepts was based on a small-scale ethnography, situated interviews, and design experience. Moreover, the thesis compares designer intention and actual user experiences of a prototype that was installed in nine homes in a residential area in Stockholm for three months. This was done in order to elicit tacit knowledge about how the concept was used in real-world domestic settings, to challenge everyday routines, and to enable both users and designers to critically reflect on artefacts and practices. From a design perspective, contributions include design approaches to communicating energy use: visualizations for showing relationships between behaviour and electricity consumption, shapes and forms to direct action, means for turning restrictions caused by energy conservation into central parts of the product experience, and ways to promote sustainable behaviour with positive driving forces based on user lifestyles. The general results indicate that inclusion is of great importance when designing energy awareness artefacts; all members of the household should be able to access, interact with, and reflect on their energy use. Therefore, design-related aspects such as placement and visibility, as well as how the artefact might affect the social interactions in the home, become central. Additionally, the thesis argues that these types of artefacts can potentially create awareness accompanied by negative results such as stress. A challenge for the designer is to create artefacts that communicate and direct energy use in ways that are attractive and can be accepted by all household members as a possible way of life.

Broms, Loove

2011-07-01

308

System interactions and energy savings in a hot dry climate  

Energy Technology Data Exchange (ETDEWEB)

To evaluate opportunities for reducing cooling energy use in a hot dry climate, two new production houses located near Phoenix, Arizona, were studied: (1) a control home built with standard construction and (2) a prototype home with an integrated package of energy-saving features. The prototype's energy-saving features included spectrally selective windows, interior air handler location, low-loss ducts, and high efficiency air-conditioning equipment. Both houses were monitored while unoccupied for a period of several weeks during very hot weather to evaluate cooling energy sue. A comparison of short periods of detailed data showed a cooling energy use reduction of approximately 40% during peak summer conditions. Effects of the various energy-saving measures and their interactions were separated by a series of tests that focused on specific components of the overall cooling load. It is important to understand the interactions of shell measures with mechanical system measures to properly size equipment and minimize overall system costs. An experimental technique was also developed to directly measure the contribution of window solar gains to overall cooling loads.

Farrar, S.; Hancock, E.; Anderson, R.

1998-07-01

309

Electronic interactions of medium-energy ions in hafnium dioxide  

Science.gov (United States)

In this article, the electronic interaction of medium-energy ions with hafnium dioxide is studied. Stopping cross sections for He ions in the energy range from 30 to 160 keV have been measured in backscattering experiments from thin films of HfO2 on Si using time-of-flight medium-energy ion scattering. The observed energy loss for helium ions is found to be high compared to expectations from earlier results for hydrogen in HfO2, a result which indicates a contribution from energy-loss processes that is different from direct excitation of electron-hole pairs in close collisions. Furthermore, data exhibit a significant deviation from velocity proportionality. A discussion of the results, together with data from studies for H and He in SiO2, show characteristic differences which are traced back to different electronic structures of the target materials and their influence on the charge-exchange channels that are active in the interaction with helium. Charge exchange, in turn, via shifted mean-charge states, will influence the observed ionization along the ion track. The results can furthermore serve as reference values for ion-beam-based depth profiling at medium and low ion energies.

Primetzhofer, D.

2014-03-01

310

Simulations of structure formation in interacting dark energy cosmologies  

International Nuclear Information System (INIS)

The evidence in favor of a dark energy component dominating the Universe, and driving its presently accelerated expansion, has progressively grown during the last decade of cosmological observations. If this dark energy is given by a dynamic scalar field, it may also have a direct interaction with other matter fields in the Universe, in particular with cold dark matter. Such interaction would imprint new features on the cosmological background evolution as well as on the growth of cosmic structure, like an additional long-range fifth-force between massive particles, or a variation in time of the dark matter particle mass. We present here the implementation of these new physical effects in the N-body code GADGET-2, and we discuss the outcomes of a series of high-resolution N-body simulations for a selected family of interacting dark energy models. We interestingly find, in contrast with previous claims, that the inner overdensity of dark matter halos decreases in these models with respect to ?CDM, and consistently halo concentrations show a progressive reduction for increasing couplings. Furthermore, the coupling induces a bias in the overdensities of cold dark matter and baryons that determines a decrease of the halo baryon fraction below its cosmological value. These results go in the direction of alleviating tensions between astrophysical observations and the predictions of the ?CDM model on small scales, thereby opening new room for coupled dark energy models as an alternative to the cosmological constant.

2009-10-01

311

Simulations of structure formation in interacting dark energy cosmologies  

Energy Technology Data Exchange (ETDEWEB)

The evidence in favor of a dark energy component dominating the Universe, and driving its presently accelerated expansion, has progressively grown during the last decade of cosmological observations. If this dark energy is given by a dynamic scalar field, it may also have a direct interaction with other matter fields in the Universe, in particular with cold dark matter. Such interaction would imprint new features on the cosmological background evolution as well as on the growth of cosmic structure, like an additional long-range fifth-force between massive particles, or a variation in time of the dark matter particle mass. We present here the implementation of these new physical effects in the N-body code GADGET-2, and we discuss the outcomes of a series of high-resolution N-body simulations for a selected family of interacting dark energy models. We interestingly find, in contrast with previous claims, that the inner overdensity of dark matter halos decreases in these models with respect to LAMBDACDM, and consistently halo concentrations show a progressive reduction for increasing couplings. Furthermore, the coupling induces a bias in the overdensities of cold dark matter and baryons that determines a decrease of the halo baryon fraction below its cosmological value. These results go in the direction of alleviating tensions between astrophysical observations and the predictions of the LAMBDACDM model on small scales, thereby opening new room for coupled dark energy models as an alternative to the cosmological constant.

Baldi, M., E-mail: mbaldi@mpa-garching.mpg.d [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 16, D-69120 Heidelberg (Germany); Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild Strasse 1, D-85748 Garching (Germany)

2009-10-15

312

Propargylic cation-induced intermolecular electrophilic addition-semipinacol rearrangement.  

Science.gov (United States)

A novel propargylic electrophile-induced tandem intermolecular addition-semipinacol rearrangement was developed efficiently under mild conditions. Various allylic silylether substrates as well as Co-complexed propargylic species were applicable to this protocol and gave a series of synthetically useful ?-propargyl spirocyclic ketones in moderate to good yields. Its synthetic application was also demonstrated by an efficient construction of the key tricyclic moiety of daphlongamine E. PMID:24589678

Shao, Hui; Zhang, Xiao-Ming; Wang, Shao-Hua; Zhang, Fu-Min; Tu, Yong-Qiang; Yang, Chao

2014-05-01

313

Propargylic cation-induced intermolecular electrophilic addition–semipinacol rearrangement.  

Science.gov (United States)

A novel propargylic electrophile-induced tandem intermolecular addition-semipinacol rearrangement was developed efficiently under mild conditions. Various allylic silylether substrates as well as Co-complexed propargylic species were applicable to this protocol and gave a series of synthetically useful ?-propargyl spirocyclic ketones in moderate to good yields. Its synthetic application was also demonstrated by an efficient construction of the key tricyclic moiety of daphlongamine E. PMID:24904943

Shao, Hui; Zhang, Xiao-Ming; Wang, Shao-Hua; Zhang, Fu-Min; Tu, Yong-Qiang; Yang, Chao

2014-06-01

314

Intramolecular and intermolecular DNA ligation mediated by topoisomerase II  

DEFF Research Database (Denmark)

The ability of topoisomerase II to mediate a number of DNA rearrangements was examined at the molecular level. For this purpose a new type of defined donor and acceptor substrate have been developed, and used for studies of the intramolecular and intermolecular DNA ligation reactions of topoisomerase II. Intramolecular ligation occurred only to single-stranded acceptor molecules with the ability to base-pair to the donor substrate, while the intermolecular ligation reaction displayed a strong preference for double-stranded acceptor molecules with a short four base, single-stranded region. The efficiency of the intermolecular ligation reaction was highly dependent on base-pairing between the acceptor molecule and the DNA donor cleaved by topoisomerase II. Thus, acceptor molecules containing a blunt end or a four base 5' overhang without base-pairing ability ligated with an approximately eightfold reduced efficiency, as compared with the base-pairing control. Experiments demonstrated that the enzyme can ligate DNA molecules, where nucleotides were either removed or inserted in the employed acceptor molecules. The results indicate that topoisomerase II might be responsible for similar rearrangements in vivo, since gapped and nicked DNA structures appear as intermediates in processes such as replication and repair. The reaction is, however, likely to be constrained by the requirement of base-pairing for ligation.

Schmidt, Vibe K; Sørensen, Boe S

1994-01-01

315

Energy Transfer and Triadic Interactions in Compressible Turbulence  

Science.gov (United States)

Using a two-point closure theory, the Eddy-Damped-Quasi-Normal-Markovian (EDQNM) approximation, we have investigated the energy transfer process and triadic interactions of compressible turbulence. In order to analyze the compressible mode directly, the Helmholtz decomposition is used. The following issues were addressed: (1) What is the mechanism of energy exchange between the solenoidal and compressible modes, and (2) Is there an energy cascade in the compressible energy transfer process? It is concluded that the compressible energy is transferred locally from the solenoidal part to the compressible part. It is also found that there is an energy cascade of the compressible mode for high turbulent Mach number (M(sub t) greater than or equal to 0.5). Since we assume that the compressibility is weak, the magnitude of the compressible (radiative or cascade) transfer is much smaller than that of solenoidal cascade. These results are further confirmed by studying the triadic energy transfer function, the most fundamental building block of the energy transfer.

Bataille, F.; Zhou, Ye; Bertoglio, Jean-Pierre

1997-01-01

316

Intriguing relations of interaction energy components in stacked nucleic acids  

Science.gov (United States)

Major components of the interaction energy that define several approximate levels starting from second order Möller-Plesset theory were studied for 58 stacked nucleic acid dimers. They included typical B-DNA and A-DNA structures, and selected published geometries. A survey of the various terms yields an unexpected correlation between the Pauli exchange and dispersion or correlation terms, which holds for each class of similar planar geometries and for various basis sets. The geometries that exhibit these correlations span a specific range of molecular overlaps when compared to a model benzene-pyridine stacked dimer. Also, the relationship between electrostatic interactions and MP2 stabilization energies reported earlier is confirmed and a prediction interval of practical relevance is estimated.

Langner, Karol M.; Sokalski, W. Andrzej; Leszczynski, J.

2007-09-01

317

Post-$Planck$ constraints on interacting vacuum energy  

CERN Document Server

We present improved constraints on an interacting vacuum model using updated astronomical observations including the first data release from Planck. We consider a model with one dimensionless parameter, $\\alpha$, describing the interaction between dark matter and vacuum energy (with fixed equation of state $w=-1$). The background dynamics correspond to a generalised Chaplygin gas cosmology, but the perturbations have a zero sound speed. The tension between the value of the Hubble constant, $H_0$, determined by Planck data plus WMAP polarisation (Planck+WP) and that determined by the Hubble Space Telescope (HST) can be alleviated by energy transfer from dark matter to vacuum ($\\alpha>0$). A positive $\\alpha$ increases the allowed values of $H_0$ due to parameter degeneracy within the model using only CMB data. Combining with additional datasets of including supernova type Ia (SN Ia) and baryon acoustic oscillation (BAO), we can significantly tighten the bounds on $\\alpha$. Redshift-space distortions (RSD), whi...

Wang, Yuting; Zhao, Gong-Bo; Xu, Lixin

2014-01-01

318

Interacting viscous dark energy in Bianchi type-I Universe  

Science.gov (United States)

A solution to the coincidence and Big Rip problems on the bases of an anisotropic space-time is proposed. To do so, we study the interaction between viscous dark energy and dark matter in the scope of the Bianchi type-I Universe. We parameterize the viscosity and the interaction between the two fluids by constants ? 0 and ? respectively. A detailed investigation on the cosmological implications of this parametrization has been made. We have also performed a geometrical diagnostic by using the statefinder pairs { s, r} and { q, r} in order to differentiate between different dark energy models. Moreover, we fit the coupling parameter ? as well as the Hubble's parameter H 0 of our model by minimizing the ? 2 through the age differential method, involving a direct measurement of H.

Amirhashchi, Hassan

2014-06-01

319

Self-interaction errors in nuclear energy density functionals  

CERN Document Server

When applied to a single nucleon, nuclear energy density functionals may yield a non-vanishing internal energy thus implying that the nucleon is interacting with itself. It is shown how to avoid this unphysical feature for semi-local phenomenological functionals containing all possible bilinear combinations of local densities and currents up to second order in the derivatives. The method outlined in this Rapid Communication could be easily extended to functionals containing higher order terms, and could serve as a guide for constraining the time-odd part of the functional.

Chamel, N

2010-01-01

320

Time-dependent interacting dark energy and transient acceleration  

CERN Document Server

We investigate cosmological scenarios in which dark matter and dark energy interact with a time-dependent phenomenological form. Starting from simple and extending to more complicated ansatzes, we obtain analytical expressions for the evolutions of the deceleration and the various density parameters. We find that depending on the choices of the model parameters, in the far future the universe can either result to a dark-energy domination, in which the late-time acceleration is permanent, or to a dark-matter domination after passing through a transient accelerating phase.

Chen, Xi-ming; Saridakis, Emmanuel N

2014-01-01

 
 
 
 
321

Screening effects in the ultrahigh energy neutrino interactions  

CERN Document Server

We study possible saturation effects in the total cross-section describing interaction of ultrahigh energy neutrinos with nucleons. This analysis is performed within the two approaches, i.e. within the Golec-Biernat W\\"usthoff saturation model and within the scheme unifying the DGLAP and BFKL dynamics incorporating non-linear screening effects which follow from the Balitzki-Kovchegov equation. The structure functions in both approaches are constrained by HERA data. It is found that screening effects affect extrapolation of the neutrino-nucleon total cross-sections to ultrahigh neutrino energies $E_{\

Kutak, K; Kutak, Krzysztof; Kwiecinski, Jan

2003-01-01

322

Analytic energy gradients for constrained DFT-configuration interaction  

Science.gov (United States)

The constrained density functional theory-configuration interaction (CDFT-CI) method has previously been used to calculate ground-state energies and barrier heights, and to describe electronic excited states, in particular conical intersections. However, the method has been limited to evaluating the electronic energy at just a single nuclear configuration, with the gradient of the energy being available only via finite difference. In this paper, we present analytic gradients of the CDFT-CI energy with respect to nuclear coordinates, which gives the potential for accurate geometry optimization and molecular dynamics on both the ground and excited electronic states, a realm which is currently quite challenging for electronic structure theory. We report the performance of CDFT-CI geometry optimization for representative reaction transition states as well as molecules in an excited state. The overall accuracy of CDFT-CI for computing barrier heights is essentially unchanged whether the energies are evaluated at geometries obtained from quadratic configuration-interaction singles and doubles (QCISD) or CDFT-CI, indicating that CDFT-CI produces very good reaction transition states. These results open up tantalizing possibilities for future work on excited states.

Kaduk, Benjamin; Tsuchimochi, Takashi; Van Voorhis, Troy

2014-05-01

323

Neutral current neutrino-nucleus interactions at intermediate energies  

Science.gov (United States)

We have extended our model for charged current neutrino-nucleus interactions developed in Phys. Rev. C 73, 065502 (2006) to neutral current reactions. For the elementary neutrino-nucleon interaction, we take into account quasielastic scattering, ? excitation, and the excitation of the resonances in the second resonance region. Our model for the neutrino-nucleus collisions includes in-medium effects such as Fermi motion, Pauli blocking, nuclear binding, and final-state interactions. They are implemented by means of the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) coupled-channel transport model. This allows us to study exclusive channels, namely pion production and nucleon knockout. We find that final-state interactions modify considerably the distributions through rescattering, charge-exchange, and absorption. Side-feeding induced by charge-exchange scattering is important in both cases. In the case of pions, there is a strong absorption associated with the in-medium pionless decay modes of the ?, while nucleon knockout exhibits a considerable enhancement of low-energy nucleons because of rescattering. At neutrino energies above 1 GeV, we also obtain that the contribution to nucleon knockout from ? excitation is comparable to that from quasielastic scattering.

Leitner, T.; Alvarez-Ruso, L.; Mosel, U.

2006-12-01

324

Neutral current neutrino-nucleus interactions at intermediate energies  

International Nuclear Information System (INIS)

We have extended our model for charged current neutrino-nucleus interactions developed in Phys. Rev. C 73, 065502 (2006) to neutral current reactions. For the elementary neutrino-nucleon interaction, we take into account quasielastic scattering, ? excitation, and the excitation of the resonances in the second resonance region. Our model for the neutrino-nucleus collisions includes in-medium effects such as Fermi motion, Pauli blocking, nuclear binding, and final-state interactions. They are implemented by means of the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) coupled-channel transport model. This allows us to study exclusive channels, namely pion production and nucleon knockout. We find that final-state interactions modify considerably the distributions through rescattering, charge-exchange, and absorption. Side-feeding induced by charge-exchange scattering is important in both cases. In the case of pions, there is a strong absorption associated with the in-medium pionless decay modes of the ?, while nucleon knockout exhibits a considerable enhancement of low-energy nucleons because of rescattering. At neutrino energies above 1 GeV, we also obtain that the contribution to nucleon knockout from ? excitation is comparable to that from quasielastic scattering

2006-12-01

325

Energy-dependent interactions in few-body systems  

International Nuclear Information System (INIS)

Energy-dependent interactions in few-body systems are discussed. A class of multichannel few-body scattering models which are characterized by the simultaneous presence of and communication between two different types of channels. First, usual two- and three-particle scattering channels (external ones), hamiltonians for which have ordinary spectral properties. Second, the internal channels, hamiltonians for which have only a point spectrum. Faddeev equations for external and internal channels are discussed

1987-06-16

326

Moriond 2012, QCD and High Energy Interactions: Experimental Summary  

CERN Multimedia

The Moriond conference on QCD and High Energy Interactions has been a most exciting and interesting event once more. This year's edition has been characterized by a very large amount of new results from the LHC experiments. However, also the experiments at other present or past accelerators are still giving extremely important input to our quest for the understanding of nature at shortest distance scales. In this review I will attempt to summarize the main experimental highlights of this conference.

Dissertori, Günther

2012-01-01

327

On the nuclear interaction. Potential, binding energy and fusion reaction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The nuclear interaction is responsible for keeping neutrons and protons joined in an atomic nucleus. Phenomenological nuclear potentials, fitted to experimental data, allow one to know about the nuclear behaviour with more or less success where quantum mechanics is hard to be used. A nuclear potential is suggested and an expression for the potential energy of two nuclear entities, either nuclei or nucleons, is developed. In order to estimate parameters in this expression, so...

Casinos, I.

2008-01-01

328

How does Casimir energy fall? IV. Gravitational interaction of regularized quantum vacuum energy  

CERN Document Server

Several years ago we demonstrated that the Casimir energy for perfectly reflecting and imperfectly reflecting parallel plates gravitated normally, that is, obeyed the equivalence principle. At that time the divergences in the theory were treated only formally, without proper regularization, and the coupling to gravity was limited to the canonical energy-momentum-stress tensor. Here we strengthen the result by removing both of those limitations. We consider, as a toy model, massless scalar fields interacting with semitransparent ($\\delta$-function) potentials defining parallel plates, which become Dirichlet plates for strong coupling. We insert space and time point-split regulation parameters, and obtain well-defined contributions to the self- energy of each plate, and the interaction energy between the plates. (This self-energy does not vanish even in the conformally-coupled, strong-coupled limit.) We also compute the local energy density, which requires regularization near the plates. In general, the energy ...

Milton, K A; Fulling, S A; Parashar, Prachi

2014-01-01

329

Effect of intermolecular hydrogen bonding, vibrational analysis and molecular structure of a biomolecule: 5-Hydroxymethyluracil  

Science.gov (United States)

In the present work, the experimental and theoretical vibrational spectra of 5-hydroxymethyluracil were investigated. The FT-IR (4000-400 cm-1) spectrum of the molecule in the solid phase was recorded. The geometric parameters (bond lengths and bond angles), vibrational frequencies, Infrared intensities of the title molecule in the ground state were calculated using density functional B3LYP and M06-2X methods with the 6-311++G(d,p) basis set for the first time. The optimized geometric parameters and theoretical vibrational frequencies were found to be in good agreement with the corresponding experimental data, and with the results found in the literature. The vibrational frequencies were assigned based on the potential energy distribution using the VEDA 4 program. The dimeric form of 5-hydroxymethyluracil molecule was also simulated to evaluate the effect of intermolecular hydrogen bonding on its vibrational frequencies. It was observed that the Nsbnd H stretching modes shifted to lower frequencies, while its in-plane and out-of-plane bending modes shifted to higher frequencies due to the intermolecular Nsbnd H⋯O hydrogen bond. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and diagrams were presented.

Ç?rak, Ça?r?; Sert, Yusuf; Ucun, Fatih

2014-06-01

330

Interaction energies of large clusters from many-body expansion  

Science.gov (United States)

In the canonical supermolecular approach, calculations of interaction energies for molecular clusters involve a calculation of the whole cluster, which becomes expensive as the cluster size increases. We propose a novel approach to this task by demonstrating that interaction energies of such clusters can be constructed from those of small subclusters with a much lower computational cost by applying progressively lower-level methods for subsequent terms in the many-body expansion. The efficiency of such ``stratified approximation'' many-body approach (SAMBA) is due to the rapid convergence of the many-body expansion for typical molecular clusters. The method has been applied to water clusters (H2O)n, n = 6, 16, 24. For the hexamer, the best results that can be obtained with current computational resources in the canonical supermolecular method were reproduced to within about one tenth of the uncertainty of the canonical approach while using 24 times less computer time in the many-body expansion calculations. For (H2O)24, SAMBA is particularly beneficial and we report interaction energies with accuracy that is currently impossible to obtain with the canonical supermolecular approach. Moreover, our results were computed using two orders of magnitude smaller computer resources than used in the previous best calculations for this system. We also show that the basis-set superposition errors should be removed in calculations for large clusters.

Góra, Urszula; Podeszwa, Rafa?; Cencek, Wojciech; Szalewicz, Krzysztof

2011-12-01

331

Revisiting the interacting model of new agegraphic dark energy  

CERN Document Server

In this paper, a new version of the interacting model of new agegraphic dark energy (INADE) is proposed and analyzed in detail. The interaction between dark energy and dark matter is reconsidered. The interaction term $Q=bH_0\\rho_{\\rm de}^\\alpha\\rho_{\\rm dm}^{1-\\alpha}$ is adopted, which abandons the Hubble expansion rate $H$ and involves both $\\rho_{\\rm de}$ and $\\rho_{\\rm dm}$. Moreover, the new initial condition for the agegraphic dark energy is used, which solves the problem of accommodating baryon matter and radiation in the model. The solution of the model can be given using an iterative algorithm. A concrete example for the calculation of the model is given. Furthermore, the model is constrained by using the combined Planck data (Planck+BAO+SNIa+$H_0$) and the combined WMAP-9 data (WMAP+BAO+SNIa+$H_0$). Three typical cases are considered: (A) $Q=bH_0\\rho_{\\rm de}$, (B) $Q=bH_0\\sqrt{\\rho_{\\rm de}\\rho_{\\rm dm}}$, and (C) $Q=bH_0\\rho_{\\rm dm}$, which correspond to $\\alpha=1$, 1/2, and 0, respectively. The...

Zhang, Jing-Fei; Zhang, Xin

2014-01-01

332

Post-Planck constraints on interacting vacuum energy  

Science.gov (United States)

We present improved constraints on an interacting vacuum model using updated astronomical observations including the first data release from Planck. We consider a model with one dimensionless parameter, ?, describing the interaction between dark matter and vacuum energy (with fixed equation of state w=-1). The background dynamics correspond to a generalized Chaplygin gas cosmology, but the perturbations have a zero sound speed. The tension between the value of the Hubble constant, H0, determined by Planck data plus WMAP polarization (Planck +WP) and that determined by the Hubble Space Telescope (HST) can be alleviated by energy transfer from dark matter to vacuum (?>0). A positive ? increases the allowed values of H0 due to parameter degeneracy within the model using only cosmic microwave background data. Combining with additional data sets of including supernova type Ia (SN Ia) and baryon acoustic oscillation (BAO), we can significantly tighten the bounds on ?. Redshift-space distortions (RSD), which constrain the linear growth of structure, provide the tightest constraints on vacuum interaction when combined with Planck+WP, and prefer energy transfer from vacuum to dark matter (?0, but not both at the same time.

Wang, Yuting; Wands, David; Zhao, Gong-Bo; Xu, Lixin

2014-07-01

333

Simulations of structure formation in interacting dark energy cosmologies  

CERN Document Server

The evidence in favor of a dark energy component dominating the Universe, and driving its presently accelerated expansion, has progressively grown during the last decade of cosmological observations. If this dark energy is given by a dynamic scalar field, it may also have a direct interaction with other matter fields in the Universe, in particular with cold dark matter. Such interaction would imprint new features on the cosmological background evolution as well as on the growth of cosmic structure, like an additional long-range fifth-force between massive particles, or a variation in time of the dark matter particle mass. We review here the implementation of these new physical effects in the N-body code GADGET-2, and we discuss the outcomes of a series of high-resolution N-body simulations for a selected family of interacting dark energy models, as already presented in Baldi et al. [20]. We interestingly find, in contrast with previous claims, that the inner overdensity of dark matter halos decreases in these...

Baldi, Marco

2009-01-01

334

Effects of pair correlation functions on intermolecular nuclear relaxation by translational and rotational diffusion in liquids  

International Nuclear Information System (INIS)

In order to study the intermolecular relaxation due to magnetic dipolar interactions, we calculate the spectral densities resulting from random translational and rotational motions of spherical molecules carrying off-centre spins. The relative translational motion is treated in the frame-work of a general diffusion equation (the Smoluchowski equation) which takes into account the existence of effective forces between the molecules. This model implies a pair correlation function. i.e. a non unifom relative distribution of the molecules. The analytical calculations are carried out by taking correctly into account the hard sphere boundary conditions for the molecules. Explicit numerical calculations of the spectral densities are performed using finite difference methods and the pair correlation function of Verlet and Weiss obtained by computer experiments. The resulting calculations allow one to interpret the relaxation exhibited by benzene and some of its monohalogen derivatives which has been measured by Jonas et al. at various pressures. The effects of pair correlation and eccentricity contribute to a noticeable enhancement of the spectral densities, especially as the frequency increases. The translational correlation times calculated from the Stokes formula and those deduced from intermolecular relaxation studies are compared. It is shown that in order to distinguish which of the dynamical models is appropriate, measurements must be made as a function of frequency

1978-01-01

335

Intermolecular complexation and phase separation in aqueous solutions of oppositely charged biopolymers.  

Science.gov (United States)

Turbidity measurements performed at 450nm were used to follow the process of complex formation, and phase separation in gelatin-agar aqueous solutions. Acid (Type-A) and alkali (Type-B) processed gelatin (polyampholyte) and agar (anionic polyelectrolyte) solutions, both having concentration of 0.1% (w/v) were mixed in various proportions, and the mixture was titrated (with 0.01 M HCl or NaOH) to initiate associative complexation that led to coacervation. The titration profiles clearly established observable transitions in terms of the solution pH corresponding to the first occurrence of turbidity (pH(C), formation of soluble complexes), and a point of turbidity maximum (pH(phi), formation of insoluble complexes). Decreasing the pH beyond pH(phi) drove the system towards precipitation. The values of pH(C) and pH(phi) characterized the initiation of the formation of intermolecular charge neutralized soluble aggregates, and the subsequent formation of microscopic coacervate droplets. These aggregates were characterized by dynamic light scattering. It was found that Type-A and -B gelatin samples formed soluble intermolecular complexes (and coacervates) with agar molecules through electrostatic and patch-binding interactions, respectively. PMID:17367849

Singh, S Santinath; Siddhanta, A K; Meena, Ramavatar; Prasad, Kamalesh; Bandyopadhyay, S; Bohidar, H B

2007-07-01

336

Electrochemical study of the intermolecular electron transfer to Pseudomonas aeruginosa cytochrome cd1 nitrite reductase  

International Nuclear Information System (INIS)

The kinetics of electron transfer reaction between cytochrome cd1 nitrite reductase (NiR) from Pseudomonas aeruginosa and various physiological/non physiological redox partners was investigated using cyclic voltammetry at the pyrolytic graphite electrode. While NiR did not exchange electron with the electrode, cytochrome c551 and azurin, both from Ps. aeruginosa, behaved as fast electrochemical systems. The intermolecular electron transfers between NiR and cytochrome c551 or azurin as electron shuttles, in the presence of nitrite, were studied. Second order rate constants of 2x106 and 1.4x105 M-1 s-1 are calculated for cytochrome c551 and azurin, respectively. The dependence of the second-order rate constant on ionic strength and pH is discussed. Finally, the effect of the global charge of the electron shuttles was explored using differently charged species (proteins or small ions). The experimental results suggest involvement of polar interactions as well as of hydrophobic contacts in the protein recognition prior to the intermolecular electron transfer. As the cross-reaction between Ps. nautica cytochrome c552 and Ps. aeruginosa NiR was shown to be as efficient as the catalytic reaction involving the physiological partners, it is concluded to a 'pseudo-specificity' in the recognition between NiR and the electron donor

2003-04-05

337

Two-dimensional infrared spectroscopy of intermolecular hydrogen bonds in the condensed phase.  

Science.gov (United States)

Hydrogen bonding plays a key role in the structural, physical, and chemical properties of liquids such as water and in macromolecular structures such as proteins. Vibrational spectroscopy is an important tool for understanding hydrogen bonding because it provides a way to observe local molecular geometries and their interaction with the environment. Linear vibrational spectroscopy has mapped characteristic changes of vibrational spectra and the occurrence of new bands that form upon hydrogen bonding. However, linear vibrational spectroscopy gives very limited insight into ultrafast dynamics of the underlying molecular interactions, such as the motions of hydrogen-bonded groups, energy dissipation and delocalization, and the fluctuations within hydrogen-bonded structures that occur in the ultrafast time domain. Nonlinear vibrational spectroscopy with its femtosecond time resolution can discern these dynamic processes in real time and has emerged as an important tool for unraveling molecular dynamics and for quantifying interactions that govern the vibrational and structural dynamics of hydrogen bonds. This Account reviews recent progress originating from third-order nonlinear methods of coherent multidimensional vibrational spectroscopy. Ultrafast dynamics of intermolecular hydrogen bonds are addressed for a number of prototype systems: hydrogen-bonded carboxylic acid dimers in an aprotic liquid environment, the disordered fluctuating hydrogen-bond network of liquid water, and DNA oligomers interacting with water. Cyclic carboxylic acid dimers display a rich scheme of vibrational couplings, resulting in OH stretching absorption bands with highly complex spectral envelopes. Two-dimensional spectroscopy of acetic acid dimers in a nonpolar liquid environment demonstrates that multiple Fermi resonances of the OH stretching mode with overtones and combination tones of fingerprint vibrations dominate both the 2D and linear absorption spectra. The coupling of the OH stretching mode with low-frequency hydrogen-bonding modes leads to additional progressions and coherent low-frequency hydrogen-bond motions in the subpicosecond time domain. In water, the 2D spectra reveal ultrafast spectral diffusion on a sub-100 fs time scale caused by the ultrafast structural fluctuations of the strongly coupled hydrogen-bond network. Librational motions play a key role for the ultrafast loss of structural memory. Spectral diffusion rates are enhanced by resonant transfer of OH stretching quanta between water molecules, typically occurring on a 100 fs time scale. In DNA oligomers, femtosecond nonlinear vibrational spectroscopy resolves NH and OH stretching bands in the highly congested infrared spectra of these molecules, which contain alternating adenine-thymine pairs. Studies at different levels of hydration reveal the spectral signatures of water molecules directly interacting with the phosphate groups of DNA and of a second water species forming a fluctuating environment around the DNA oligomers. We expect that the application of 2D infrared spectroscopy in an extended spectral range will reveal the intrinsic coupling between water and specific functional units of DNA. PMID:19425543

Elsaesser, Thomas

2009-09-15

338

Modified holographic Ricci dark energy coupled to interacting dark matter and a non interacting baryonic component  

CERN Multimedia

We examine a Friedmann-Robertson-Walker universe filled with interacting dark matter, modified holographic Ricci dark energy (MHRDE), and a decoupled baryonic component.The estimations of the cosmic parameters with Hubble data lead to an age of the universe of $13.17 {\\rm Gyr}$ and show that the MHRDE is free from the cosmic-age problem at low redshift ($0 \\leq z \\leq 2$) in contrast to holographic Ricci dark energy (HRDE) case. We constrain the parameters with the Union2 data set and contrast with the Hubble data. We also study the behavior of dark energy at early times by taking into account the severe bounds found at recombination era and/or at big bang nucleosynthesis. The inclusion of a non interacting baryonic matter forces that the amount of dark energy at $z_{t} \\sim {\\cal O}(1)$ changes abruptly implying that $\\Omega_x (z\\simeq 1100) =0.03$, so the bounds reported by the forecast of Planck and CMBPol experiments are more favored for the MHRDE model than in the case of HRDE cutoff. For the former mode...

Chimento, Luis P; Richarte, Martín G

2013-01-01

339

Casimir interaction energies for magneto-electric ?-function plates  

International Nuclear Information System (INIS)

We present boundary conditions for the electromagnetic fields on a ?-function plate, having both electric and magnetic properties, sandwiched between two magneto-electric semi-infinite half spaces. The optical properties for an isolated ?-function plate are shown to be independent of the longitudinal material properties of the plate. The Casimir-Polder energy between an isotropically polarizable atom and a magneto-electric ?-function plate is attractive for a purely electric ?- function plate, repulsive for a purely magnetic ?-function plate, and vanishes for the simultaneous perfect conductor limit of both electric and magnetic properties of the ?-function plate. The interaction energy between two identical ?-function plates is always attractive. It can be attractive or repulsive when the plates have electric and magnetic properties interchanged and reproduces Boyer's result for the interaction energy between perfectly conducting electric and magnetic plates. The change in the Casimir-Polder energy in the presence of a ?-function plate on a magneto-electric substrate is substantial when the substrate is a weak dielectric.

2013-01-01

340

Effective NN interaction for multistep processes at low energies  

International Nuclear Information System (INIS)

The complexity of nuclear reactions involving multistep processes has inhibited the use of microscopic methods already standard for the description of reactions leading to discrete final states and giant resonances. The simplest 1 fm range Yukawa interaction was thus chosen in the frame of the Feshbach-Kerman-Koonin (FKK) theory in order to describe the effective NN interaction leading to particle-hole excitations. Moreover, its strength V0 has been the only FKK free parameter adjusted to reproduce the experimental data. On the other hand, the actual aim of the FKK analyses is to include ingredients developed in other independent nuclear structure/reaction studies, leading to reduced uncertainties in the cross section calculations as well as better test of various theory assumptions (e.g., particle-hole density form). Adoption of the M3Y realistic NN interaction is among the main points of this new approach. Density- and energy-dependent effective DDM3Y, BDM3Y and HLM3Y interactions, based on the Reid and Paris NN-potentials and describing successfully the nucleon-nucleus scattering within low-density nuclear matter, seem to be most suitable in this respect. Their reliability can be studied by means of calculation of the corresponding optical model potentials (OMP) and their comparison to either the phenomenological OMPs or the parametrized form of the isoscalar real component obtained through nuclear matter calculations (JLM). Thus, the previous full-folding model has provided OMP depths, volume integrals and rms radii in rather good agreement with the phenomenological and JLM data. Furthermore, analysis of the nucleon elastic-scattering angular distributions is now also involved within the trial of effective NN interaction and corresponding OMP suitable for further description of multistep processes at low incident energies. (authors)

1999-01-01

 
 
 
 
341

Laser-Plasma Interactions in High-Energy Density Plasmas  

International Nuclear Information System (INIS)

Laser-plasma interactions (LPI) have been studied experimentally in high-temperature, high-energy density plasmas. The studies have been performed using the Omega laser at the Laboratory for Laser Energetics (LLE), Rochester, NY. Up to 10 TW of power was incident upon reduced-scale hohlraums, distributed in three laser beam cones. The hot hohlraums fill quickly with plasma. Late in the laser pulse, most of the laser energy is deposited at the laser entrance hole, where most of the LPI takes place. Due to the high electron temperature, the stimulated Raman scattering (SRS) spectrum extends well beyond ?0/2, due to the Bohm-Gross shift. This high-temperature, high-energy density regime provides a unique opportunity to study LPI beyond inertial confinement fusion (ICF) conditions

2005-09-04

342

Cosmological evolution of interacting dark energy in Lorentz violation  

CERN Document Server

The cosmological evolution of an interacting scalar field model in which the scalar field has its interaction with dark matter, radiation, and baryon via Lorentz violation is investigated. We propose a model of interaction through the effective coupling parameter, $\\bar{\\beta}$, $Q_m = - \\dot{\\bar{\\beta}}\\rho_m/\\bar{\\beta}$. We apply the dynamical systems to study the linear dynamics of an interacting model and show that the dynamics is completely determined by only two parameters $\\lambda_1$ and $\\lambda_2$. We determine all critical points and study their stability. By choosing the values of $\\lambda_1$ and $\\lambda_2$, we show the numerical solution for different interesting cases. There exists the sequence of radiation, dark matter, and scalar field dark energy but the baryon is sub dominant. The model allows the possible of the universe in the phantom phase with the constant potential. We also find that the vacuum expectation value of the vector field determines the time variations in the gravitational c...

Zen, Freddy P; Gunara, Bobby E; Triyanta,; Purwanto, A

2008-01-01

343

Transetherification on Polyols by Intra- and Intermolecular Nucleophilic Substitutions  

Science.gov (United States)

Transetherification on polyols involving intra- and intermolecular nucleophilic substitutions is reported. Di- or trialkoxide formation of propane-1,3-diol or 2-(hydroxymethyl)propane-1,3-diol derivatives by NaH triggers the reaction via oxetanes formation, where the order to add NaH and a polyol significantly influences the yields of products. It was demonstrated that the protective group on the pentaerythritol skeleton is apparently transferred to the hydrophilic and hydrophobic chain molecules bearing a leaving group in one-step, and a protective group conversion from tosyl to benzyl was successful using a benzyl-appending triol to afford a desired product in 67% yield.

Muraoka, Takahiro; Adachi, Kota; Chowdhury, Rainy; Kinbara, Kazushi

2014-01-01

344

Different approaches to adjusting band offsets at intermolecular interfaces  

Energy Technology Data Exchange (ETDEWEB)

We show that at the hetero-molecular interface, the molecular band offsets can be modified by either adjusting the dopant or dopant concentration of one or both molecular layers or by changing the dipole orientation at the intermolecular interface. Photoemission studies reveal the changes in electronic structure and diode devices exhibit conduction properties that are altered in response to changes to the molecular band offsets. As a demonstration, thin film copper phthalocyanine to crystalline ferroelectric copolymer poly(vinylidene fluoride with trifluoroethylene) heterojunction diodes, without additional dopants, are compared with doped polyaniline layers on the crystalline ferroelectric copolymer poly(vinylidene fluoride with trifluoroethylene)

Dowben, P.A. [Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588-0111 (United States)], E-mail: pdowben@unl.edu; Xiao, Jie; Xu, Bo; Sokolov, Andrei [Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588-0111 (United States); Doudin, B. [Institut de Physique Applique de Physique et Chimie des Materiaux de Strasbourg, 23 rue du Loess, B.P. 20, 67034 Strasbourg Cedex 2 (France)

2008-05-15

345

New interactions in the dark sector mediated by dark energy  

CERN Multimedia

Cosmological observations have revealed the existence of a dark matter sector, which is commonly assumed to be made up of one particle species only. However, this sector might be more complicated than we currently believe: there might be more than one dark matter species (for example two components of cold dark matter or a mixture of hot and cold dark matter) and there may be new interactions between these particles. In this paper we study the possibility of multiple dark matter species and interactions mediated by a dark energy field. We study both the background and the perturbation evolution in these scenarios. We find that the background evolution of a system of multiple dark matter particles (with constant couplings) mimics a single fluid with a time-varying coupling parameter. However, this is no longer true on the perturbative level. We study the case of attractive and repulsive forces as well as a mixture of cold and hot dark matter particles.

Brookfield, A W; Hall, L M H

2007-01-01

346

Impurity formation energies and effective interactions in DMS  

International Nuclear Information System (INIS)

We use a recently developed method (Phil. Mag. 88 (2008), 2777) based on the TB-LMTO scheme to calculate the electronic structure of atomic clusters embedded in an ideal crystal or in an effective medium that represents a random alloy. We determine from the first principles impurity formation energies and effective interatomic interactions (i.e. the parameters of the alloy Ising Hamiltonian that governs structural stability of materials) and exchange interactions (i.e. parameters of the Heisenberg Hamiltonian that determines the magnetic structure). We present the results for impurities in (Ga,Mn)As alloys and for vacancies and alkali metal impurities in zirconia that can induce the the so-called d0-magnetism.

2009-03-22

347

New interactions in the dark sector mediated by dark energy  

Science.gov (United States)

Cosmological observations have revealed the existence of a dark matter sector, which is commonly assumed to be made up of one particle species only. However, this sector might be more complicated than we currently believe: there might be more than one dark matter species (for example, two components of cold dark matter or a mixture of hot and cold dark matter) and there may be new interactions between these particles. In this paper we study the possibility of multiple dark matter species and interactions mediated by a dark energy field. We study both the background and the perturbation evolution in these scenarios. We find that the background evolution of a system of multiple dark matter particles (with constant couplings) mimics a single fluid with a time-varying coupling parameter. However, this is no longer true on the perturbative level. We study the case of attractive and repulsive forces as well as a mixture of cold and hot dark matter particles.

Brookfield, Anthony W.; van de Bruck, Carsten; Hall, Lisa M. H.

2008-02-01

348

Constraining interacting dark energy with observational $H(z)$ data  

CERN Document Server

We investigate observational constraints on two interacting dark energy models with the newly revised $H(z)$ data, as well as the cosmic microwave background (CMB) observation from the Wilkinson Microwave Anisotropy Probe (WMAP7) results, the baryonic acoustic oscillation (BAO) observation from the spectroscopic Sloan Digital Sky Survey (SDSS) Data Release and the Union2 SNe Ia set, by using the Markov Chain Monte Carlo (MCMC) method. For the $\\gamma_m$IDE and $\\gamma_d$IDE models, the special case ($\\gamma_m=0$ ($\\gamma_d=0$), $w_X=-1$, corresponding to the $\\Lambda$CDM with no interaction) is excluded at $1\\sigma$ with $H(z)$+BAO+CMB, while the joint analysis with SNe Ia+BAO+CMB and $H(z)$+SNe Ia+BAO+CMB indicates that the $\\Lambda$CDM model is still included within $1\\sigma$ error region.

Cao, Shuo; Zhu, Zong-Hong

2013-01-01

349

On the K^+D Interaction at Low Energies  

CERN Document Server

The Kd reactions are considered in the impulse approximation with NN final-state interactions (NN FSI) taken into account. The realistic parameters for the KN phase shifts are used. The "quasi-elastic" energy region, in which the elementary KN interaction is predominantly elastic, is considered. The theoretical predictions are compared with the data on the K^+d->K^+pn, K^+d->K^0pp, K^+d->K^+d and K^+d total cross sections. The NN FSI effect in the reaction K^+d->K^+pn has been found to be large. The predictions for the Kd cross sections are also given for slow kaons, produced from phi(1020) decays, as the functions of the isoscalar KN scattering length a_0. These predictions can be used to extract the value of a_0 from the data.

Tarasov, V E; Kudryavtsev, A E; Weinberg, V M

2007-01-01

350

New interactions in the dark sector mediated by dark energy  

International Nuclear Information System (INIS)

Cosmological observations have revealed the existence of a dark matter sector, which is commonly assumed to be made up of one particle species only. However, this sector might be more complicated than we currently believe: there might be more than one dark matter species (for example, two components of cold dark matter or a mixture of hot and cold dark matter) and there may be new interactions between these particles. In this paper we study the possibility of multiple dark matter species and interactions mediated by a dark energy field. We study both the background and the perturbation evolution in these scenarios. We find that the background evolution of a system of multiple dark matter particles (with constant couplings) mimics a single fluid with a time-varying coupling parameter. However, this is no longer true on the perturbative level. We study the case of attractive and repulsive forces as well as a mixture of cold and hot dark matter particles

2008-02-15

351

Nonlinear interactions and energy exchange between liquid sloshing modes  

Science.gov (United States)

Non-stationary effects of the resonance energy exchange between liquid sloshing modes for square-base tanks are analyzed in terms of new descriptive variables namely energy partition and coherency (phase shift) indexes. In particular, it is shown that such a couple represents conjugate variables of an effective Hamiltonian system whose phase plane captures all possible effects of the modal interaction. Furthermore, the presence of damping affects only the temporal scale of the dynamics but still preserves the Hamiltonian structure of equations that provides the existence of first integral. As a result, analytical solution for the nonlinear interaction of predominant modes is obtained in quadratures. The dynamic properties of the modal interaction are controlled by a single parameter which depends upon the fluid depth. Transitions of the phase plane diagram reveal that, above some critical depth, the diagonal in-phase and out-of-phase sloshing modes disappear while only clockwise and counterclockwise swirling, and running phase modes are possible. Whereas the quadratures are invertible within the class of elliptic functions, an explicit solution for the important critical case is obtained in terms of elementary functions. The approach is illustrated on the sloshing model for a square-base tank suggested by Ikeda et al. (T. Ikeda, R.A. Ibrahim, Y. Harata, T. Kuriyama, Nonlinear liquid sloshing in a square tank subjected to obliquely horizontal excitation, J. Fluid Mech., 700 (2012) 304-328.) However, formulated in general terms of coupled oscillators, the approach seems to have a wider area of applicability dealing with non-stationary effects of resonance interactions with nonlinear beating effects in physics and classical mechanics.

Pilipchuk, V. N.

2013-11-01

352

Buckyplates and buckybowls: examining the effects of curvature on ?-? interactions.  

Science.gov (United States)

?-? interactions are integral to many areas of chemistry, biochemistry, and materials science. Here we use electronic structure theory to analyze how ?-? interactions change as the ?-systems are curved in model complexes based on coronene and corannulene dimers. Curvature redistributes electronic charge in the ?-cloud and creates a dipole moment in these systems, leading to enhanced intermolecular electrostatic interactions in the concave-convex (nested) geometries that are the focus of this work. Curvature of both monomers also has a geometric effect on the interaction by decreasing the average C-C distance between monomers and by increasing the magnitude of both favorable London dispersion interactions and unfavorable exchange-repulsion interactions. Overall, increasing curvature in nested ?-? interactions leads to more favorable interaction energies regardless of the native state of the monomers, except at short distances where the most highly curved systems are less favorable as exchange repulsion terms begin to dominate the interaction. PMID:23137341

Kennedy, Matthew R; Burns, Lori A; Sherrill, C David

2012-12-01

353

Molecular dynamics simulation of acetamide solvation using interaction energy components: Application to structural and energy properties  

International Nuclear Information System (INIS)

Molecular dynamics simulation of an aqueous solution of acetamide was performed using Lennard-Jones 12-6-1 potentials to describe the solute-solvent interactions, and TIP3P to describe the water-water interactions. The Morokuma decomposition scheme and the ESIE solute atomic charges were used to reproduce the molecular parameters of the solute-water interaction potential. The results showed that the functions that use the EX-PL-DIS-ES interaction model lead to good values of the structural and energy properties (in particular, the hydration shell and the solvation energies) when they are compared with those from using AMBER-derived parameters, and with the available theoretical and experimental data

2006-08-21

354

Accurate prediction of cation-? interaction energy using substituent effects.  

Science.gov (United States)

Substituent effects on cation-? interactions have been quantified using a variety of ?-X···M(+) complexes where ?, X, and M(+) are the ?-system, substituent, and cation, respectively. The cation-? interaction energy, E(M(+)), showed a strong linear correlation with the molecular electrostatic potential (MESP) based measure of the substituent effect, ?V(min) (the difference between the MESP minimum (V(min)) on the ?-region of a substituted system and the corresponding unsubstituted system). This linear relationship is E(M(+)) = C(M(+))(?V(min)) + E(M(+))' where C(M(+)) is the reaction constant and E(M(+))' is the cation-? interaction energy of the unsubstituted complex. This relationship is similar to the Hammett equation and its first term yields the substituent contribution of the cation-? interaction energy. Further, a linear correlation between C(M(+))() and E(M(+))()' has been established, which facilitates the prediction of C(M(+)) for unknown cations. Thus, a prediction of E(M(+)) for any ?-X···M(+) complex is achieved by knowing the values of E(M(+))' and ?V(min). The generality of the equation is tested for a variety of cations (Li(+), Na(+), K(+), Mg(+), BeCl(+), MgCl(+), CaCl(+), TiCl(3)(+), CrCl(2)(+), NiCl(+), Cu(+), ZnCl(+), NH(4)(+), CH(3)NH(3)(+), N(CH(3))(4)(+), C(NH(2))(3)(+)), substituents (N(CH(3))(2), NH(2), OCH(3), CH(3), OH, H, SCH(3), SH, CCH, F, Cl, COOH, CHO, CF(3), CN, NO(2)), and a large number of ?-systems. The tested systems also include multiple substituted ?-systems, viz. ethylene, acetylene, hexa-1,3,5-triene, benzene, naphthalene, indole, pyrrole, phenylalanine, tryptophan, tyrosine, azulene, pyrene, [6]-cyclacene, and corannulene and found that E(M)(+) follows the additivity of substituent effects. Further, the substituent effects on cationic sandwich complexes of the type C(6)H(6)···M(+)···C(6)H(5)X have been assessed and found that E(M(+)) can be predicted with 97.7% accuracy using the values of E(M(+))' and ?V(min). All the ?-X···M(+) systems showed good agreement between the calculated and predicted E(M(+))() values, suggesting that the ?V(min) approach to substituent effect is accurate and useful for predicting the interactive behavior of substituted ?-systems with cations. PMID:22616763

Sayyed, Fareed Bhasha; Suresh, Cherumuttathu H

2012-06-14

355

Three intermolecular bonds form a weak but rigid complex: O(CH3)2...N2O.  

Science.gov (United States)

The rotational spectrum of the dimethylether (DME)-N(2)O complex has been studied for the normal and three (15)N isotopomers, leading to rotational, centrifugal distortion, and nuclear quadrupole coupling constants, the molecular structure, and a binding energy of 8.4 kJ mol(-1). Here, it is shown that many DME-N(2)O-type complexes are bound with three intermolecular bonds and that the internal rotation splitting due to the methyl groups in the rotational spectrum was fixed by complexation, implying that many weak intermolecular bonds can fix the flexible motions and maintain a rigid structure. If the model we are proposing for DME-N(2)O-type complexes can be applied to biomolecules, it may give something a clue to solve the biological riddle on the dynamic character of biomolecules that have conflicting properties of being rigid and binding weakly. PMID:19323514

Yamanou, Kenji; Tatamitani, Yoshio; Ogata, Teruhiko

2009-04-16

356

Interacting Ghost Dark Energy Models with Variable $G$ and $\\Lambda$  

CERN Document Server

In this paper we consider several phenomenological models of variable $\\Lambda$. Model of a flat Universe with variable $\\Lambda$ and $G$ is accepted. It is well known, that varying $G$ and $\\Lambda$ gives rise to modified field equations and modified conservation laws, which gives rise to many different manipulations and assumptions in literature. We will consider two component fluid, which parameters will enter to $\\Lambda$. Interaction between fluids with energy densities $\\rho_{1}$ and $\\rho_{2}$ assumed as $Q=3Hb(\\rho_{1}+\\rho_{2})$. We have numerical analyze of important cosmological parameters like EoS parameter of the composed fluid and deceleration parameter $q$ of the model.

Sadeghi, J; Movsisyan, A; Farahani, H

2013-01-01

357

Electrodynamical interactions of high energy particles with matter  

International Nuclear Information System (INIS)

A short review of the electrodynamical effects connected with the passage of a charged ultrarelativistic particle through different substances is given. The main attention is paid to the properties of the X-ray transition radiation generated at the passage of charge through the interface between various media, a single plate, a stack of plates, a nonregular medium, a monocrystall. The radiation emitted by electron shells of atoms interacting with the ultrarelativistic charge is considered. The detectors designed for high energy particle identification using X-ray transition radiation are reviewed in brief

1974-01-01

358

Low-Energy $KN$ Interactions at a $\\phi$-Factory  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper is the written version of a talk presented at the "VIIth Winter School of Hadronic Physics", held in Folgaria (Trento), Italy, February 10--15, 1992. We intend to illustrate in this lecture the possibilities opening up at machines planned for the nineties for low--energy kaon--nucleon interactions, keeping the focus on the theoretical problems they should help to solve. We shall deal here only with the $\\phi$--factory DA$\\Phi$NE$^1$ and consider, for brevity...

Gensini, Paolo M.

1992-01-01

359

Polarizabilities of the intermolecular contacts in BEDT-TTF and BEDO-TTF molecular crystals  

Energy Technology Data Exchange (ETDEWEB)

In BEDT-TTF and BEDO-TTF molecular crystals the indicatrix orientation, the optic axes angle, the birefringence, and the absorption tensor were measured in the VIS and NIR spectral range. The principal refractive indices and the corresponding optical axes have been calculated by tensorial addition of the bond polarizabilities of all bonds in the molecules. Moreover calculations with relative polarizibilities were carried out. Comparing the calculated and the measured values shows that the polarizabilities of the molecules only can not yield the measured indicatrix and axes angle. Polarizabilities with other orientations must be involved. Therefore the crystal structures have been examined. In BEDT-TTF ten, and in BEDO-TTF four different contacts between the molecules exist with contact distances lower than the van der Waals distances. Assigning polarizabilities to these contacts can explain the measured behaviour. The absorption spectra confirm the intermolecular interaction. (orig.)

Helberg, H.W. (3. Physikalisches Inst., Univ. Goettingen (Germany)); Lenz, H.C. (3. Physikalisches Inst., Univ. Goettingen (Germany))

1993-03-29

360

Spectral energy transfer of atmospheric gravity waves through sum and difference nonlinear interactions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nonlinear interactions of gravity waves are studied with a two-dimensional, fully nonlinear model. The energy exchanges among resonant and near-resonant triads are examined in order to understand the spectral energy transfer through interactions. The results show that in both resonant and near-resonant interactions, the energy exchange between two high frequency waves is strong, but the energy transfer from large to small vertical scale waves is rather weak. This suggests that the energy casc...

Huang, K. M.; Liu, A. Z.; Zhang, S. D.; Yi, F.; Li, Z.

2012-01-01

 
 
 
 
361

Geant4 simulation of high energy muon interactions  

CERN Document Server

The set of models describing production and interaction of high energy muons is developed in the framework of the Geant4 toolkit. It includes following processes or models: ionization of high energy muons with radiative corrections, bremsstrahlung, electron-positron pair production, muon induced nuclear reactions, gamma annihilation into muon pair, positron annihilation into muon pair, and into pion pair. These models are essential for LHC experiments, for understanding of the background for underground detectors, for simulation of atmospheric showers induced by muons and for simulation of backgrounds in future colliders. The applicability area of the models extended to 1 PeV. The major use-cases and methods of validation of the models are discussed.

Bogdanov, Alexey G; Ivanchenko, V N; Kelner, S R; Kokoulin, Rostislav P; Maire, Michel; Rybin, Alexander M; Urbàn, László

2004-01-01

362

Screening effects in the ultra-high energy neutrino interactions  

Science.gov (United States)

We study possible saturation effects in the total crosssections describing the interaction of ultra-high energy neutrinos with nucleons. This analysis is performed within two approaches, i.e., within the Golec-Biernat-Wüsthoff saturation model and within the scheme unifying the DGLAP and BFKL dynamics incorporating non-linear screening effects which follow from the Balitzki-Kovchegov equation. The structure functions in both approaches are constrained by HERA data. It is found that screening effects affect the extrapolation of the neutrino-nucleon total cross-sections to ultra-high neutrino energies E_{?} and reduce their magnitude by a factor equal to about 2 at E_{?} ˜ 10^{12} GeV. This reduction becomes amplified by nuclear shadowing in the case of the neutrino-nucleus cross-sections and an approximate estimate of this effect is performed.

Kutak, K.; Kwiecinski, J.

2003-08-01

363

Screening effects in the ultra-high energy neutrino interactions  

CERN Document Server

We study possible saturation effects in the total crosssections describing the interaction of ultra-high energy neutrinos with nucleons. This analysis is performed within two approaches, i.e., within the Golec-Biernat-Wuesthoff saturation model and within the scheme unifying the DGLAP and BFKL dynamics incorporating non-linear screening effects which follow from the Balitzki-Kovchegov equation. The structure functions in both approaches are constrained by HERA data. It is found that screening effects affect the extrapolation of the neutrino-nucleon total cross-sections to ultra-high neutrino energies E subnu and reduce their magnitude by a factor equal to about 2 at E subnu propor to 10 sup 1 sup 2 GeV. This reduction becomes amplified by nuclear shadowing in the case of the neutrino-nucleus cross-sections and an approximate estimate of this effect is performed. (orig.)

Kutak, K

2003-01-01

364

Screening effects in the ultra-high energy neutrino interactions  

International Nuclear Information System (INIS)

We study possible saturation effects in the total crosssections describing the interaction of ultra-high energy neutrinos with nucleons. This analysis is performed within two approaches, i.e., within the Golec-Biernat-Wuesthoff saturation model and within the scheme unifying the DGLAP and BFKL dynamics incorporating non-linear screening effects which follow from the Balitzki-Kovchegov equation. The structure functions in both approaches are constrained by HERA data. It is found that screening effects affect the extrapolation of the neutrino-nucleon total cross-sections to ultra-high neutrino energies E? and reduce their magnitude by a factor equal to about 2 at E??1012 GeV. This reduction becomes amplified by nuclear shadowing in the case of the neutrino-nucleus cross-sections and an approximate estimate of this effect is performed. (orig.)

2003-08-01

365

Analysis of elastic interactions of hadrons at high energies  

International Nuclear Information System (INIS)

Study of elastic interactions of hadrons at high energies if of great interest due to the fact that the amplitude of this process is the simplest, and at the same time, it is a fundamental object for theoretical and experimental researches. Study of this process allows one to have a quantitative check of various theories and models, and to make a critical selection. By using of fundamental property of theory - unitarity condition of scattering matrix - elastic scattering can be connected with inelastic reaction. Based on S-channel unitarity condition expressing elastic amplitude via inelastic overlapping function, to study the latter, as well as to describe the experimentally measured characteristics of hadron-nucleon interactions at high-energies, as well as for results prediction. By using experimental data on differential cross-section of elastic scattering of hadrons at various energies and by theoretical information on ratio of a real part and an imaginary part of scattering amplitude ?(t) the t-dependence of inelastic and elastic overlapping functions is studied. Influence of a zigzag form of differential cross-section of elastic pp(p) scattering on profile function and inelastic overlapping function to violation of geometric scaling was studied. In frames of the scaling the general expressions for s- and t-dependences of inelastic overlapping function are derived. Comparison of this function in three elastic scattering models was carried out. It was demonstrated that one would need to assume that hadrons become blacker at central part in order to correctly describe experimental angular distribution data. Dependence of differential cross-section on transfer momentum square for elastic hadrons scattering at energies of ISR and SPS in the model of inelastic overlapping function is studied. (author)

2004-10-01

366

Search for Quarks in High-Energy Neutrino Interactions  

CERN Document Server

This experiment is a search for quarks produced in high energy neutrino interactions. Neutrino interactions take place in a 23-ton lead target and are recognized by one or more particles crossing the counter hodoscopes S1 and S2, together with the absence of an incident particle signal in the initial veto counter V^0.\\\\ \\\\ The lead is viewed by an avalanche chamber to measure the specific ionization of the charged secondaries produced in the @n-interaction with high accuracy even in jet-like events, and by a series of two pairs of scintillation counter hodoscopes (ST1, ST2). The latter provide time-of-flight measurements and dE/dx measurements for a fast analysis in low and medium multiplicity provide a trigger for the chamber. \\\\ \\\\ In order to reduce the background in the set-up, very low momentum particles (mainly due to cascading processes in the target) are separated out by a @= 1 T.m magnet placed behind the target. \\\\ \\\\ A system of wire chambers W1, W2, which register both the position and the time at...

2002-01-01

367

Saturation model for two-photon interactions at high energies  

International Nuclear Information System (INIS)

We formulate and analyse a saturation model for the total ?? and ?* ?* cross-sections and for the real photon structure function F2?(x,Q2). The model is based on a picture in which the ?* ?* total cross-section for arbitrary photon virtualities is driven by the interaction of colour dipoles into which the virtual photons fluctuate. The cross-section describing this interaction is assumed to satisfy the saturation property with the saturation radius taken from the Golec-Biernat and Wuesthoff analysis of the ?*p interaction at HERA. The model is supplemented by the QPM and non-pomeron reggeon contributions. The model gives a very good description of the data on the ?? total cross-section, on the photon structure function F2?(x,Q2) at low x and on the ?* ?* cross-section extracted from LEP double tagged events. The production of heavy flavours in ?? collisions is also studied. Predictions of the model for the very high energy range which will be probed at future linear colliders are given. (orig.)

2002-04-01

368

Saturation model for two-photon interactions at high energies  

CERN Document Server

We formulate and analyse a saturation model for the total gamma gamma and gamma* gamma* cross-sections and for the real photon structure function F_2^gamma(x,Q^2). The model is based on a picture in which the gamma* gamma* total cross-section for arbitrary photon virtualities is driven by the interaction of colour dipoles, into which the virtual photons fluctuate. The cross-section describing this interaction is assumed to satisfy the saturation property with the saturation radius taken from the Golec-Biernat and Wusthoff analysis of the gamma* p interaction at HERA. The model is supplemented by the QPM and non-pomeron reggeon contributions. The model gives a very good description of the data on the gamma gamma total cross-section, on the photon structure function F_2^gamma(x,Q^2) at low x and on the gamma* gamma* cross-section extracted from LEP double tagged events. Production of heavy flavours in gamma gamma collisions is also studied. Predictions of the model for the very high energy range which will be p...

Timneanu, N; Motyka, L; 10.1007/s100520200893

2002-01-01

369

Saturation model for two-photon interactions at high energies  

Science.gov (United States)

We formulate and analyse a saturation model for the total ? ? and ?^* ?^* cross-sections and for the real photon structure function F_2^{?}(x,Q^2). The model is based on a picture in which the ?^* ?^* total cross-section for arbitrary photon virtualities is driven by the interaction of colour dipoles into which the virtual photons fluctuate. The cross-section describing this interaction is assumed to satisfy the saturation property with the saturation radius taken from the Golec-Biernat and Wüsthoff analysis of the ?^*p interaction at HERA. The model is supplemented by the QPM and non-pomeron reggeon contributions. The model gives a very good description of the data on the ? ? total cross-section, on the photon structure function F_2^{?}(x,Q^2) at low x and on the ?^* ?^* cross-section extracted from LEP double tagged events. The production of heavy flavours in ? ? collisions is also studied. Predictions of the model for the very high energy range which will be probed at future linear colliders are given.

Tîmneanu, N.; Kwieci?ski, J.; Motyka, L.

2002-04-01

370

Low-energy positron interactions with atoms and molecules  

International Nuclear Information System (INIS)

This paper is a review of low-energy positron interactions with atoms and molecules. Processes of interest include elastic scattering, electronic and vibrational excitation, ionization, positronium formation and annihilation. An overview is presented of the currently available theoretical and experimental techniques to study these phenomena, including the use of trap-based positron beam sources to study collision processes with improved energy resolution. State-resolved measurements of electronic and vibrational excitation cross sections and measurement of annihilation rates in atoms and molecules as a function of incident positron energy are discussed. Where data are available, comparisons are made with analogous electron scattering cross sections. Resonance phenomena, common in electron scattering, appear to be less common in positron scattering. Possible exceptions include the sharp onsets of positron-impact electronic and vibrational excitation of selected molecules. Recent energy-resolved studies of positron annihilation in hydrocarbons containing more than a few carbon atoms provide direct evidence that vibrational Feshbach resonances underpin the anomalously large annihilation rates observed for many polyatomic species. We discuss open questions regarding this process in larger molecules, as well as positron annihilation in smaller molecules where the theoretical picture is less clear. (topical review)

2005-03-28

371

The kinetic peculiarities of intermolecular proton transfer from NH groups of octa( m-trifluoromethylphenyl)tetraazaporphin in the nitrogen base-benzene system  

Science.gov (United States)

The acid-base interaction of octa( m-trifluoromethylphenyl)tetraazaporphin with nitrogen bases in benzene was studied. The rates of intermolecular transfer of sterically screened NH group protons from octa( m-trifluoromethylphenyl)tetraazaporphin to n-butylamine and tert-butylamine were found to be low. A scheme of the process was suggested. The influence of the nature of bases on the kinetic parameters of acid-base interactions was studied.

Petrov, O. A.; Khelevina, O. G.; Kuzmina, E. L.

2010-09-01

372

Modeling Dark Energy Through AN Ising Fluid with Network Interactions  

Science.gov (United States)

We show that the dark energy (DE) effects can be modeled by using an Ising perfect fluid with network interactions, whose low redshift equation of state (EoS), i.e. ?0, becomes ?0 = -1 as in the ?CDM model. In our picture, DE is characterized by a barotropic fluid on a lattice in the equilibrium configuration. Thus, mimicking the spin interaction by replacing the spin variable with an occupational number, the pressure naturally becomes negative. We find that the corresponding EoS mimics the effects of a variable DE term, whose limiting case reduces to the cosmological constant ?. This permits us to avoid the introduction of a vacuum energy as DE source by hand, alleviating the coincidence and fine tuning problems. We find fairly good cosmological constraints, by performing three tests with supernovae Ia (SNeIa), baryonic acoustic oscillation (BAO) and cosmic microwave background (CMB) measurements. Finally, we perform the Akaike information criterion (AIC) and Bayesian information criterion (BIC) selection criteria, showing that our model is statistically favored with respect to the Chevallier-Polarsky-Linder (CPL) parametrization.

Luongo, Orlando; Tommasini, Damiano

2014-03-01

373

Study of low-energy antineutrino interactions on protons  

International Nuclear Information System (INIS)

We present a study of antineutrino interactions in hydrogen obtained in a 138 000-picture run at the BNL 7-ft bubble chamber. The antineutrino beam had an energy distribution that peaked at approx. 1.1 GeV. The cross section measured for charged-currect interactions is sigma (nu-barp ? ?++anything) = (0.32 +- 0.08) x 10-38 x [E/sub nu-bar/ (GeV)] cm2. The neutral-current cross section is sigma (nu-barp ? nu-barp?+?-) =5.5/sup +4.4//sub -2.6/ x 10-40 cm2. The ratio of strangeness-changing to non-strangeness-changing charged currents is R/sub s/=0.06/sup +0.13//sub -0.05/. An upper limit determined for charm production is sigma/sub c/-40 cm2 at the 90% confidence level. From the momentum-transfer distribution we measure average Q2 for inelastic charged-current events with energy greater than 2 GeV, 2>= (0.10 +- 0.03)[E/sub nu-bar/ (GeV)]+(0.10 +- 0.09) (GeV/c)2. Using a maximum-likelihood method we determine from the quasielastic events nu-barp ? ?+n an axial-vector mass M/sub A/=0.9/sup +0.4//sub -0.3/ GeV/c2

1980-02-01

374

The nature of interactions in nicotinamide crystal.  

Science.gov (United States)

In this study, we analyze the nature of intermolecular interactions in nicotinamide complexes appearing in conformations found in the crystal structure, including many-body effects. In doing so, we employ symmetry-adapted perturbation theory based on density functional theory description of monomers, and we perform the many-body variational-perturbational interaction energy decomposition. The principal finding of this study is that the stability of nicotinamide complexes is a complicated interplay of four (large in magnitude) interaction-energy components, i.e. induction, dispersion, electrostatic and exchange repulsion. However, the last two contributions cancel each other out to a large extent. In the case of considered three-body complexes, the nonadditivity effects are found to be not important. Based on the results of topological analysis of charge densities we characterized also the properties of short H ? H contact and identified it as a weak noncovalent closed shell interaction. PMID:24863341

Misiaszek, Tomasz; Czy?nikowska, Zaneta

2014-06-01

375

Combining climate and energy policies: synergies or antagonism? Modeling interactions with energy efficiency instruments  

International Nuclear Information System (INIS)

In addition to the already present Climate and Energy package, the European Union (EU) plans to include a binding target to reduce energy consumption. We analyze the rationales the EU invokes to justify such an overlapping and develop a minimal common framework to study interactions arising from the combination of instruments reducing emissions, promoting renewable energy (RE) production and reducing energy demand through energy efficiency (EE) investments. We find that although all instruments tend to reduce GHG emissions and although a price on carbon tends also to give the right incentives for RE and EE, the combination of more than one instrument leads to significant antagonisms regarding major objectives of the policy package. The model allows to show in a single framework and to quantify the antagonistic effects of the joint promotion of RE and EE. We also show and quantify the effects of this joint promotion on ETS permit price, on wholesale market price and on energy production levels. (authors)

2012-01-01

376

ATP-dependent interaction of the cytosolic domains of the inwardly rectifying K+ channel Kir6.2 revealed by fluorescence resonance energy transfer.  

Science.gov (United States)

ATP-sensitive K(+) (K(ATP)) channels play important roles in the regulation of membrane excitability in many cell types. ATP inhibits channel activity by binding to a specific site formed by the N and C termini of the pore-forming subunit, Kir6.2, but the structural changes associated with this interaction remain unclear. Here, we use fluorescence resonance energy transfer (FRET) to study the ATP-dependent interaction between the N and C termini of Kir6.2 using a construct bearing fused cyan and yellow fluorescent proteins (ECFP-Kir6.2-EYFP). When expressed in human embryonic kidney cells, ECFP-Kir6.2-EYFP/SUR1 channels displayed FRET that was augmented by agonist stimulation and diminished by metabolic poisoning. Addition of ATP to permeabilized cells or isolated plasma membrane sheets increased FRET. FRET changes were abolished by Kir6.2 mutations that altered ATP-dependent channel closure and channel gating. In the wild-type channel, the ATP concentrations, which increased FRET (EC(50) = 1.36 mM), were significantly higher than those causing channel inhibition (IC(50) = 0.29 mM). Demonstrating the existence of intermolecular interactions, a dimeric construct comprising two molecules of Kir6.2 linked head-to-tail (ECFP-Kir6.2-Kir6.2-EYFP) displayed less FRET than the monomer in the absence of nucleotide but still exhibited ATP-dependent FRET increases (EC(50) = 1.52 mM) and channel inhibition. We conclude that binding of ATP to Kir6.2, (i). alters the interaction between the N- and C-terminal domains, (ii). probably involves both intrasubunit and intersubunit interactions, (iii). reflects ligand binding not channel gating, and (iv). occurs in intact cells when subplasmalemmal [ATP] changes in the millimolar range. PMID:14681552

Tsuboi, Takashi; Lippiat, Jonathan D; Ashcroft, Frances M; Rutter, Guy A

2004-01-01

377

The ratio of charged-to-total energy in high-energy proton-proton interactions  

International Nuclear Information System (INIS)

The ratio of charged-to-total energy in multiparticle hadronic systems produced in pp interactions has been measured. The analysis has been performed using our technique of subtracting the leading baryon effects. The results are compared with e+e- annihilation data. (orig.)

1981-02-19

378

Low energy charged particles interacting with amorphous solid water layers  

Energy Technology Data Exchange (ETDEWEB)

The interaction of charged particles with condensed water films has been studied extensively in recent years due to its importance in biological systems, ecology as well as interstellar processes. We have studied low energy electrons (3-25 eV) and positive argon ions (55 eV) charging effects on amorphous solid water (ASW) and ice films, 120-1080 ML thick, deposited on ruthenium single crystal under ultrahigh vacuum conditions. Charging the ASW films by both electrons and positive argon ions has been measured using a Kelvin probe for contact potential difference (CPD) detection and found to obey plate capacitor physics. The incoming electrons kinetic energy has defined the maximum measurable CPD values by retarding further impinging electrons. L-defects (shallow traps) are suggested to be populated by the penetrating electrons and stabilize them. Low energy electron transmission measurements (currents of 0.4-1.5 {mu}A) have shown that the maximal and stable CPD values were obtained only after a relatively slow change has been completed within the ASW structure. Once the film has been stabilized, the spontaneous discharge was measured over a period of several hours at 103 {+-} 2 K. Finally, UV laser photo-emission study of the charged films has suggested that the negative charges tend to reside primarily at the ASW-vacuum interface, in good agreement with the known behavior of charged water clusters.

Horowitz, Yonatan; Asscher, Micha [Institute of Chemistry, Hebrew University of Jerusalem, Edmund J. Safra Campus, Givat-Ram, Jerusalem 91904 (Israel)

2012-04-07

379

Low energy charged particles interacting with amorphous solid water layers  

International Nuclear Information System (INIS)

The interaction of charged particles with condensed water films has been studied extensively in recent years due to its importance in biological systems, ecology as well as interstellar processes. We have studied low energy electrons (3-25 eV) and positive argon ions (55 eV) charging effects on amorphous solid water (ASW) and ice films, 120-1080 ML thick, deposited on ruthenium single crystal under ultrahigh vacuum conditions. Charging the ASW films by both electrons and positive argon ions has been measured using a Kelvin probe for contact potential difference (CPD) detection and found to obey plate capacitor physics. The incoming electrons kinetic energy has defined the maximum measurable CPD values by retarding further impinging electrons. L-defects (shallow traps) are suggested to be populated by the penetrating electrons and stabilize them. Low energy electron transmission measurements (currents of 0.4-1.5 ?A) have shown that the maximal and stable CPD values were obtained only after a relatively slow change has been completed within the ASW structure. Once the film has been stabilized, the spontaneous discharge was measured over a period of several hours at 103 ± 2 K. Finally, UV laser photo-emission study of the charged films has suggested that the negative charges tend to reside primarily at the ASW-vacuum interface, in good agreement with the known behavior of charged water clusters.

2012-04-07

380

Laser-plasma interactions in high-energy density plasmas  

International Nuclear Information System (INIS)

Laser-plasma interactions (LPI) have been studied experimentally in high-temperature, high-energy density plasmas. The studies have been performed using the Omega laser at the Laboratory for Laser Energetics (LLE), Rochester. Up to 10 TW of power was incident upon reduced-scale hohlraums, distributed in three laser beam cones. The hot hohlraums fill quickly with plasma. Late in the laser pulse, most of the laser energy is deposited at the laser entrance hole, where most of the LPI takes place. Due to the high electron temperature, the stimulated Raman scattering (SRS) spectrum extends well beyond ?0/2, due to the Bohm-Gross shift. A comparison between hohlraums with diameters of 600, 1200 and 1600 ?m reveals how the Raman spectrum scales with the target seize, both in wavelength shift and duration. Thus, for targets with large diameters it appears that the plasma density increases to the SRS lower threshold (when the scattered signal starts to be observed) slower than for the small diameter targets. According to numerical simulations, this lower threshold value is around 0.1 n(cr) where n(cr) is the critical density. This high-temperature, high-energy density regime provides a unique opportunity to study LPI beyond inertial confinement fusion conditions

2006-06-01

 
 
 
 
381

Interacting model of new agegraphic dark energy: Cosmological evolution and statefinder diagnostic  

CERN Multimedia

Statefinder diagnosic is a useful method to distinguish different dark energy models. In this paper, we investigate the new agegraphic dark energy model with interaction between dark energy and matter component by using statefinder parameter pair $\\{r, s\\}$ and study its cosmological evolution. We plot the trajectories of the new agegraphic dark energy model for different interaction cases in the statefinder plane. As a result, the influence of the interaction on the evolution of the universe is shown in the statefinder diagrams.

Zhang, Li; Zhang, Jingfei; Zhang, Xin

2009-01-01

382

Chain-length-dependent intermolecular packing in polyphenylenes: a high pressure study  

CERN Document Server

We report on pressure-induced structural changes in crystalline oligo(para-phenylenes) containing two to six phenyl rings. The results are discussed with particular emphasis put on the implications these changes in intermolecular distances and molecular arrangement have on important bulk properties of this class of materials, such as optical response and charge transport. We performed energy dispersive x-ray diffraction in a systematic study on polycrystalline powders of biphenyl, para-terphenyl, p-quaterphenyl, p-quinquephenyl and p-sexiphenyl under hydrostatic pressure up to 60 kbar. Revisiting the crystal structures at ambient conditions reveals details in the packing principle. A linear relationship between the density at ambient conditions and the number of phenyl rings is found. High pressure data not only yields pressure-dependent lattice parameters and hints towards pressure-induced changes in the molecular arrangement but also allows for an analysis of the equations of state of these substances as a ...

Heimel, G; Oehzelt, M; Hummer, K; Koppelhuber-Bitschnau, B; Porsch, F; Ambrosch-Draxl, C; Resel, R

2003-01-01

383

Vapor-liquid nucleation of argon: exploration of various intermolecular potentials.  

Science.gov (United States)

The homogeneous vapor-liquid nucleation of argon has been explored at T=70 and 90 K using classical nucleation theory, semiempirical density functional theory, and Monte Carlo simulations using the aggregation-volume-bias algorithm with umbrella sampling and histogram-reweighting. In contrast with previous simulation studies, which employed only the Lennard-Jones intermolecular potential, the current studies were carried out using various pair potentials including the Lennard-Jones potential, a modified Buckingham exponential-six potential, the Barker-Fisher-Watts pair potential, and a recent ab initio potential developed using the method of effective diameters. It was found that the differences in the free energy of formation of the critical nuclei between the potentials cannot be explained solely in terms of the difference in macroscopic properties of the potentials, which gives a possible reason for the failure of classical nucleation theory. PMID:20815559

McGrath, Matthew J; Ghogomu, Julius N; Tsona, Narcisse T; Siepmann, J Ilja; Chen, Bin; Napari, Ismo; Vehkamäki, Hanna

2010-08-28

384

Exciton-plasmon interactions and energy transfer in nanoparticles  

Science.gov (United States)

Energy transfer between optically-excited nanocrystals coupled by the Coulomb interaction can be very efficient. The interaction of excitons and plasmons in nanocrystals leads to several effects: energy transfer between nanoparticles (NPs), electromagnetic enhancement, reduced exciton diffusion in nanowires (NWs), exciton energy shifts, and interference and non-linear phenomena [1-3]. Using kinetic equations for excitons, we model exciton transport in a NW and explain the origin of the blue shift of exciton emission observed in the recent experiments on hybrid NW-NP assemblies [2]. We also model artificial light-harvesting complexes composed of chlorophylls, bacterial reaction centers, and NPs [3]. Using superior optical properties of metal and semiconductor NPs, one can strongly enhance the efficiency of light harvesting [3]. An interaction between a discrete state of exciton and a continuum of plasmonic states can give rise to interference effects (Fano-like asymmetric resonances). These interference effects greatly enhance visibility of relatively weak exciton signals and can be used for spectroscopy of single nanoparticle and molecules. In the nonlinear regime, the Fano effect becomes strongly amplified [4]. In conclusion, our theory explains present experimental results and also provides motivation for future experiments and applications. Potential applications of dynamical exciton-plasmon systems include sensors and light-harvesting. The above theoretical studies were performed in collaboration with several groups [1-4]. [4pt] [1] A. O. Govorov, G. W. Bryant, W. Zhang, T. Skeini, J. Lee, N. A. Kotov, J. M. Slocik, and R. R. Naik, Nano Letters 6, 984 (2006).[0pt] [2] J. Lee, P. Hernandez, J. Lee, A. Govorov, and N. Kotov, Nature Materials 6, 291 (2007).[0pt] [3] A. O. Govorov and I. Carmeli, Nano Lett. 7, 620 (2007); S. Mackowski, S. W"ormke, A.J. Maier, T.H.P. Brotosudarmo, H. Harutyunyan, A. Hartschuh, A.O. Govorov, H. Scheer, C. Br"auchle, Nano Lett. 8, 558 (2008). [0pt] [4] M. Kroner, A. O. Govorov, S. Remi, B. Biedermann, S. Seidl, A. Badolato, P. M. Petroff, W. Zhang, R.Barbour, B. D. Gerardot, R. J. Warburton, and K. Karrai, Nature 451, 311 (2008).

Govorov, Alexander

2009-03-01

385

Normal-Mode Analysis for Intra- and Intermolecular Electron--Phonon Coupled Systems with Charge-Ordered and Dimer--Mott Ground States  

Science.gov (United States)

We have theoretically studied the ground-state properties of the molecular compound, Et2Me2Sb[Pd(dmit)2]2, which shows a dimer--Mott character in Pd(dmit)2 layers at high temperature and a charge order mainly stabilized by an electron--phonon interaction at low temperature. An effective extended Peierls--Hubbard model is constructed with intra- and intermolecular electronic and phonon degrees of freedom. Using mean-field approximation, the energies and optimized structures are calculated for isolated neutral, monovalent, divalent Pd(dmit)2 dimers and their two-dimensional crystallized states. The optical conductivities of the crystallized states are calculated by a single-configuration interaction method. For intramolecular vibrations, normal-mode analysis is performed, which is useful to explain the recent experimental results. Molecular vibrations with different symmetries are coupled to different combinations of electrons and holes within a molecule, so that their frequencies depend on the molecular charge in different manners. This information will be useful to analyze photoinduced transient states, where the relation between their frequencies and the molecular charge is modified from the equilibrium counterpart.

Nishioka, Keita; Yonemitsu, Kenji

2013-02-01

386

Computational prediction of monosaccharide binding free energies to lectins with linear interaction energy models.  

Science.gov (United States)

The linear interaction energy (LIE) method to compute binding free energies is applied to lectin-monosaccharide complexes. Here, we calculate the binding free energies of monosaccharides to the Ralstonia solanacearum lectin (RSL) and the Pseudomonas aeruginosa lectin-II (PA-IIL). The standard LIE model performs very well for RSL, whereas the PA-IIL system, where ligand binding involves two calcium ions, presents a major challenge. To overcome this, we explore a new variant of the LIE model, where ligand-metal ion interactions are scaled separately. This model also predicts the saccharide binding preference of PA-IIL on mutation of the receptor, which may be useful for protein engineering of lectins. PMID:22847637

Mishra, Sushil Kumar; Sund, Johan; Åqvist, Johan; Ko?a, Jaroslav

2012-11-01

387

PHOTON-HADRON INTERACTIONS AT RHIC AND LHC ENERGIES.  

Energy Technology Data Exchange (ETDEWEB)

Heavy Ion Collisions at RHIC and LHC energies are potentially an interesting laboratory for the study of QED. In these collisions, a Heavy Ion in one beam sees a highly Lorentz contracted electric field due to an oncoming beam particle. The Electric field reaches a maximum value of E {approx_equal} {gamma}{sub eff} {center_dot} Z {center_dot} e/b{sup 2}, where the apparent Lorentz factor, {gamma}{sub eff} = 2 {center_dot} {gamma}{sub beam}{sup 2} - 1. The collision may be viewed in terms of a flux of photons colliding with a stationary ion target using the equivalent photon approximation, originally introduced by Fermi in 1924. We show that the cross section for Inelastic Electromagnetic Interactions of Heavy Ions are both calculable and have been measured in the first RHIC running period.

WHITE,S.N.

2002-03-01

388

Binding energies of hypernuclei and. lambda. -nuclear interactions  

Energy Technology Data Exchange (ETDEWEB)

Variational Monte Carlo calculations have been made for the s-shell hypernuclei and also of Be with a 2..cap alpha..+..lambda.. model. The well depth is calculated variationally with the Fermi hypernetted chain method. A satisfactory description of all the relevant experimental ..lambda.. separation energies and also of the ..lambda..p scattering can be obtained with reasonable TPE ..lambda..N and ..lambda..NN forces and strongly repulsive dispersive ..lambda..NN forces which are preferred to be spin dependent. We discuss variational calculations for sub(..lambda lambda..)/sup 6/He and sub(..lambda lambda..)/sup 10/BE with ..cap alpha..+2..lambda.. and 2..cap alpha..+2..lambda.. models, and the results obtained for the ..lambda lambda.. interaction and for sub(..lambda lambda..)/sup 6/He from analysis of sub(..lambda lambda..)/sup 10/Be. Coulomb effects and charge symmetry breaking in the A=4 hypernuclei are discussed. (orig.).

Bodmer, A.R.; Usmani, Q.N.

1986-03-10

389

Binding energies of hypernuclei and. lambda. -nuclear interactions  

Energy Technology Data Exchange (ETDEWEB)

Variational Monte Carlo calculations have been made for the s-shell hypernuclei and also of /sup 9/Be hypernuclei with a 2..cap alpha.. + ..lambda.. model. The well depth is calculated variationally with the Fermi hypernetted chain method. A satisfactory description of all the relevant experimental ..lambda.. separation energies and also of the ..lambda..p scattering can be obtained with reasonable TPE ..lambda..N and ..lambda..NN forces and strongly repulsive dispersive ..lambda..NN forces which are preferred to be spin dependent. We discuss variational calculations for /sup 6/He and /sup 10/Be hypernuclei with ..cap alpha.. + 2..lambda.. and 2..cap alpha.. + 2..lambda.. models, and the results obtained for the ..lambda lambda.. interaction and for /sup 6/He hypernuclei from analysis of /sup 10/Be hypernuclei Coulomb effects and charge symmetry breaking in the A = 4 hypernuclei are discussed. 24 refs., 5 figs.

Bodmer, A.R.; Usmani, Q.N.

1985-01-01

390

Observational Constraints on Interacting Dark Matter Model Without Dark Energy  

CERN Multimedia

We constrain the Interacting Dark Matter (IDM) scenario which allows for the acceleration of the Universe without Dark Energy (Basilakos & Plionis 2009) by using the newly revised observational data including $H(z)$ data and Union2 SNe Ia via the Markov Chain Monte Carlo method. For the mimicking $\\Lambda$CDM model, we obtain a more stringent upper limit of the effective annihilation term at $\\kappa C_1\\approx 10^{-4}{Gyr}^{-1}$, and a tighter lower limit of the relevant mass of Dark Matter particles at $M_x\\approx 10^{-8}{Gev}$. For the mimicking $w$CDM model, we find the effective equation of state for the special IDM model favors the effective phantom model with a constant EoS ($w<-1$)

Cao, Shuo; Liang, Nan

2010-01-01

391

2010 Atomic & Molecular Interactions Gordon Research Conference  

Energy Technology Data Exchange (ETDEWEB)

The Atomic and Molecular Interactions Gordon Conferences is justifiably recognized for its broad scope, touching on areas ranging from fundamental gas phase and gas-condensed matter collision dynamics, to laser-molecule interactions, photophysics, and unimolecular decay processes. The meeting has traditionally involved scientists engaged in fundamental research in gas and condensed phases and those who apply these concepts to systems of practical chemical and physical interest. A key tradition in this meeting is the strong mixing of theory and experiment throughout. The program for 2010 conference continues these traditions. At the 2010 AMI GRC, there will be talks in 5 broadly defined and partially overlapping areas of intermolecular interactions and chemical dynamics: (1) Photoionization and Photoelectron Dynamics; (2) Quantum Control and Molecules in Strong Fields; (3) Photochemical Dynamics; (4) Complex Molecules and Condensed Phases; and (5) Clusters and Reaction Dynamics. These areas encompass many of the most productive and exciting areas of chemical physics, including both reactive and nonreactive processes, intermolecular and intramolecular energy transfer, and photodissociation and unimolecular processes. Gas phase dynamics, van der Waals and cluster studies, laser-matter interactions and multiple potential energy surface phenomena will all be discussed.

Todd Martinez

2010-07-23

392

Short-time behavior of the vibrational-energy-time correlation function for a one-dimensional model of diatomic molecules  

Energy Technology Data Exchange (ETDEWEB)

The short-time behavior of the vibrational-energy-time correlation function (VECF) is studied both theoretically and numerically for a one-dimensional model of diatomic molecules with harmonic intramolecular and hard intermolecular interactions. In the equipartition regime, the short-time expansion of the VECF is independent of the vibrational frequency and agrees with statistical mechanics.

Monge, A.; Cohen, E.G.D. (Rockefeller Univ., New York, NY (United States))

1992-01-01

393

Scanning probe and optical tweezer investigations of biomolecular interactions  

International Nuclear Information System (INIS)

A complex array of intermolecular forces controls the interactions between and within biological molecules. The desire to empirically explore the fundamental forces has led to the development of several biophysical techniques. Of these, the atomic force microscope (AFM) and the optical tweezers have been employed throughout this thesis to monitor the intermolecular forces involved in biomolecular interactions. The AFM is a well-established force sensing technique capable of measuring biomolecular interactions at a single molecule level. However, its versatility has not been extrapolated to the investigation of a drug-enzyme complex. The energy landscape for the force induced dissociation of the DHFR-methotrexate complex was studied. Revealing an energy barrier to dissociation located ?0.3 nm from the bound state. Unfortunately, the AFM has a limited range of accessible loading rates and in order to profile the complete energy landscape alternative force sensing instrumentation should be considered, for example the BFP and optical tweezers. Thus, this thesis outlines the development and construction an optical trap capable of measuring intermolecular forces between biomolecules at the single molecule level. To demonstrate the force sensing abilities of the optical set up, proof of principle measurements were performed which investigate the interactions between proteins and polymer surfaces subjected to varying degrees of argon plasma treatment. Complementary data was gained from measurements performed independently by the AFM. Changes in polymer resistance to proteins as a response to changes in polymer surface chemistry were detected utilising both AFM and optical tweezers measurements. Finally, the AFM and optical tweezers were employed as ultrasensitive biosensors. Single molecule investigations of the antibody-antigen interaction between the cardiac troponin I marker and its complementary antibody, reveals the impact therapeutic concentrations of heparin have up on the association and dissociation of the complex. In the thesis the AFM and optical tweezers independently provide complementary data towards the understanding of biomolecular interactions. (author)

2002-01-01

394

Energy flow in relativistic beam-plasma interactions  

International Nuclear Information System (INIS)

The experiment was performed with a 600-keV Marx generator system capable of producing current pulses from 0.5 to 15 kA. The beam was injected into a clear lucite interaction chamber filled with 10-mT helium pre-ionized to n/sub p/ = 2 x 1012cm-3. A 1-2 kG axial-guide field was used. Radiation with peak power up to 280 kW and peak efficiency of 3 x 10-5 was observed. In the short 300-ns shots, the emission persisted throughout the current pulse. In the long 1800-ns shots the emission cutoff after ? 1000 ns, well before the beam current reached its peak. To understand this beam-plasma system, a model was made that used a 30-mode Langmuir wave spectrum from k = 7 cm-1 to 120 cm-1 and one EM mode. The energy transfer between these modes was controlled by instability rates derived from the linear and nonlinear dispersion relations. Also considered was the Langmuir wave energy lost to heating by induced return current acting on the anomalous resistivity. In the model, uniform beam and plasma density and ideal beam propagation were assumed. Three observables were used to test the validity of the model: emission, ionization, and RMS plasma electric field

1987-01-01

395

Proton-nucleus interaction at low and intermediate energies  

International Nuclear Information System (INIS)

The elastic scattering of protons from a number of nuclei between "1"2C and "2"0"8Pb is the subject matter of the present study at the projectile energies 30.3, 66.5 and 1044 MeV within the framework of the generalized diffraction models of Frahn and Venter. The best fit parameter values, the cut-off angular momentum T, the rounding parameter ? and the real nuclear phase shift ? are obtained from the elastic scattering analyses of the entrance channel angular distributions. The interaction radius R, diffuseness d and the reaction cross section ?_r, have been estimated from the best fit parameters. Energy dependence of T, ? and ?_r/?R"2 and mass dependence of R are discussed. Finally, the inelastic scattering of protons exciting to the lowest 2"+ collective states in "4"2","4"4","4"8Ca, "4"8Ti and "1"4"8","1"5"4Sm and 3"- collective state in "4"0Ca are studied to check the validity of the derived elastic scattering parameters. The deformation parameters ?_2 and ?_3, so extracted are comparable with the available values in literature. (author)

2004-01-01

396

Experimental Studies of Elementary Particle Interactions at High Energies  

Energy Technology Data Exchange (ETDEWEB)

This is the final report of a program of research on ``Experimental Studies of Elementary Particle Interactions at High Energies'' of the High Energy Physics (HEP) group of The Rockefeller University. The research was carried out using the Collider Detector at Fermilab (CDF) and the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) at CERN. Three faculty members, two research associates, and two postdoctoral associates participated in this project. At CDF, we studied proton-antiproton collisions at an energy of 1.96 TeV. We focused on diffractive interactions, in which the colliding antiproton loses a small fraction of its momentum, typically less than 1%, while the proton is excited into a high mass state retaining its quantum numbers. The study of such collisions provides insight into the nature of the diffractive exchange, conventionally referred to as Pomeron exchange. In studies of W and Z production, we found results that point to a QCD-based interpretation of the diffractive exchange, as predicted in a data-driven phenomenology developed within the Rockefeller HEP group. At CMS, we worked on diffraction, supersymmetry (SUSY), dark matter, large extra dimensions, and statistical applications to data analysis projects. In diffraction, we extended our CDF studies to higher energies working on two fronts: measurement of the single/double diffraction and of the rapidity gap cross sections at 7 TeV, and development of a simulation of diffractive processes along the lines of our successful model used at CDF. Working with the PYTHIA8 Monte Carlo simulation authors, we implemented our model as a PYTHIA8-MBR option in PYTHIA8 and used it in our data analysis. Preliminary results indicate good agreement. We searched for SUSY by measuring parameters in the Constrained Minimal Supersymmetric extension of the Standard Model (CMSSM) and found results which, combined with other experimental constraints and theoretical considerations, indicate that the CMSSM is not a viable model. Expressing our results in terms of simple topologies, we exclude squark masses below 0.75 TeV and gluino masses below 1.1 TeV. Astrophysical measurements suggest that about 80% of the matter density of the Universe is non-luminous. One of the theories on dark matter attributes it to Weakly Interacting Massive Particles (WIMPs). We searched for WIMPs in 7 TeV and 8 TeV collisions at CMS and set limits on WIMP production rates, which are competitive and complementary to those of direct detection experiments. Searching for monojets (events with only one jet), which in a popular model could be produced by a jet paired by a gravitino that escapes into extra dimensions, we significantly improved the previously set limit. Our results have been used to set limits on Higgs decay to invisible particles and on production of top squarks in compressed SUSY scenarios. Statistics. We computed Bayesian reference priors for several types of measurement and used them in the analysis of CMS data; investigated the applicability of bootstrap methods to HEP measurements; studied several issues associated with simple-versus-simple hypothesis testing and applied the resulting methods to the measurement of some properties of the top quark and Higgs boson.

Goulianos, Konstantin [The Rockefeller University

2013-07-31

397

Study of high-energy neutrino neutral-current interactions  

Energy Technology Data Exchange (ETDEWEB)

From an exposure of the Fermilab 15-foot bubble chamber to the Tevatron quadrupole triplet neutrino beam, we have determined the ratio of neutral-current (NC) to charged-current (CC) interactions to be 0.288{plus minus}0.032 for events with visible hadron momentum above 10 GeV/{ital c}. The mean {nu}({bar {nu}}) event energy is 150 (110) GeV, which is higher than that for any previous beam. This result agrees with those from previous experiments at lower energies. The NC/CC ratio is derived for a combined sample of {nu} and {bar {nu}} events. A value of 0.274{plus minus}0.038 is obtained for the dominant {nu} component assuming {bar {nu}} NC/CC=0.39{plus minus}0.08. For events with visible hadron momentum above 25 GeV/{ital c}, where the neutral hadron contamination remaining in the NC sample is assumed to be negligible, the combined NC/CC is 0.323{plus minus}0.025 and the {ital K}{sup 0} production rates are 0.375{plus minus}0.064 per CC and 0.322{plus minus}0.073 per NC event. The corresponding {Lambda} rates are 0.161{plus minus}0.030 per CC and 0.113{plus minus}0.030 per NC event. The {ital K}{sup 0} and {Lambda} distributions of the fractional hadron energy variable {ital z} in NC events are consistent with those in CC events.

Aderholz, M.; Aggarwal, M.M.; Akbari, H.; Allport, P.P.; Badyal, S.K.; Ballagh, H.C.; Barth, M.; Baton, J.P.; Bingham, H.H.; Brucker, E.B.; Burnstein, R.A.; Campbell, J.R.; Cence, R.J.; Chatterjee, T.K.; Clayton, E.F.; Corrigan, G.; Coutures, C.; DeProspo, D.; Devanand; De Wolf, E.A.; Faulkner, P.J.W.; Foeth, H.; Fretter, W.B.; Gupta, V.K.; Hanlon, J.; Harigel, G.; Harris, F.A.; Jabiol, M.A.; Jacques, P.; Jain, V.; Jones, G.T.; Jones, M.D.; Kafka, T.; Kalelkar, M.; Kasper, P.; Kohli, J.M.; Koller, E.L.; Krawiec, R.J.; Lauko, M.; Lys, J.E.; Marage, P.; Milburn, R.H.; Miller, D.B.; Mittra, I.S.; Mobayyen, M.M.; Moreels, J.; Morrison, D.R.O.; Myatt, G.; Nailor, P.; Naon, R.; Napier, A.; Neveu, M.; Passmore, D.; Peters, M.W.; Peterson, V.Z.; Plano, R.; Rao, N.K.; Rubin, H.A.; Sacton, J.; Sambyal, S.S.; Schmitz, N.; Schneps, J.; Singh, J.B.; Smart, W.; Stamer, P.; Varvell, K.E.; Verluyten, L.; Wachsmuth, H.; Wainstein, S.; Willocq, S.; Yost, G.P. (University of California, Berkeley, Califor; (E632 Collaboration)

1992-04-01

398

Problem-Based Learning in 9th Grade Chemistry Class: "Intermolecular Forces"  

Science.gov (United States)

This research study aims to examine the effectiveness of a problem-based learning (PBL) on 9th grade students' understanding of intermolecular forces (dipole-dipole forces, London dispersion forces and hydrogen bonding). The student's alternate conceptions about intermolecular bonding and their beliefs about PBL were also measured. Seventy-eight…

Tarhan, Leman; Ayar-Kayali, Hulya; Urek, Raziye Ozturk; Acar, Burcin

2008-01-01

399

Origin of attraction in chalgogen-nitrogen interaction of 1,2,5-chalcogenadiazole dimers.  

Science.gov (United States)

Intermolecular interaction in the 1,2,5-chalcogenadiazole dimers was studied by ab initio molecular orbital calculations. Estimated CCSD(T) interaction energies for the thia-, selena- and tellura-diazole dimers are -3.14, -5.29, and -12.42 kcal/mol, respectively. The electrostatic and dispersion interactions are the major sources of the attraction in the dimers, although it was claimed that the orbital mixing (charge-transfer interaction) was the most prominent contribution to the stabilization. The induction (induced polarization) interaction also contributes largely to the attraction in the telluradiazole dimer. The large electrostatic and induction interactions are responsible for the strong attraction in the telluradiazole dimer. The short-range (orbital-orbital) interaction (sum of the exchange-repulsion and charge-transfer interactions) is repulsive. The directionality of the interactions increases in order of S halogen bond, which is an electrostatically driven noncovalent interaction. PMID:23659630

Tsuzuki, Seiji; Sato, Naoki

2013-06-01

400

Notes on dark energy interacting with dark matter and unparticle in loop quantum cosmology  

International Nuclear Information System (INIS)

We investigate the behavior of dark energy interacting with dark matter and unparticle in the framework of loop quantum cosmology. In four toy models, we study the interaction between the cosmic components by choosing different coupling functions representing the interaction. We found that there are only two attractor solutions namely dark energy dominated and dark matter dominated Universe. The other two models are unstable, as they predict either a dark energy filled Universe or one completely devoid of it. (orig.)

2011-08-01

 
 
 
 
401

Field theory model for dark matter and dark energy in interaction  

International Nuclear Information System (INIS)

We propose a field theory model for dark energy and dark matter in interaction. Comparing the classic