WorldWideScience
1

Energy decomposition analysis of covalent bonds and intermolecular interactions  

Science.gov (United States)

An energy decomposition analysis method is implemented for the analysis of both covalent bonds and intermolecular interactions on the basis of single-determinant Hartree-Fock (HF) (restricted closed shell HF, restricted open shell HF, and unrestricted open shell HF) wavefunctions and their density functional theory analogs. For HF methods, the total interaction energy from a supermolecule calculation is decomposed into electrostatic, exchange, repulsion, and polarization terms. Dispersion energy is obtained from second-order Møller-Plesset perturbation theory and coupled-cluster methods such as CCSD and CCSD(T). Similar to the HF methods, Kohn-Sham density functional interaction energy is decomposed into electrostatic, exchange, repulsion, polarization, and dispersion terms. Tests on various systems show that this algorithm is simple and robust. Insights are provided by the energy decomposition analysis into H2, methane C-H, and ethane C-C covalent bond formation, CH3CH3 internal rotation barrier, water, ammonia, ammonium, and hydrogen fluoride hydrogen bonding, van der Waals interaction, DNA base pair formation, BH3NH3 and BH3CO coordinate bond formation, Cu-ligand interactions, as well as LiF, LiCl, NaF, and NaCl ionic interactions.

Su, Peifeng; Li, Hui

2009-07-01

2

The same number of optimized parameters scheme for determining intermolecular interaction energies.  

Science.gov (United States)

We propose the Same Number Of Optimized Parameters (SNOOP) scheme as an alternative to the counterpoise method for treating basis set superposition errors in calculations of intermolecular interaction energies. The key point of the SNOOP scheme is to enforce that the number of optimized wave function parameters for the noninteracting system is the same as for the interacting system. This ensures a delicate balance between the quality of the monomer and dimer finite basis set calculations. We compare the SNOOP scheme to the uncorrected and counterpoise schemes theoretically as well as numerically. Numerical results for second-order Møller-Plesset perturbation theory (MP2) and coupled-cluster with single, double, and approximate triple excitations (CCSD(T)) show that the SNOOP scheme in general outperforms the uncorrected and counterpoise approaches. Furthermore, we show that SNOOP interaction energies calculated using a given basis set are of similar quality as those determined by basis set extrapolation of counterpoise-corrected results obtained at a similar computational cost. PMID:25796240

Kristensen, Kasper; Ettenhuber, Patrick; Eriksen, Janus Juul; Jensen, Frank; Jørgensen, Poul

2015-03-21

3

The same number of optimized parameters scheme for determining intermolecular interaction energies  

Science.gov (United States)

We propose the Same Number Of Optimized Parameters (SNOOP) scheme as an alternative to the counterpoise method for treating basis set superposition errors in calculations of intermolecular interaction energies. The key point of the SNOOP scheme is to enforce that the number of optimized wave function parameters for the noninteracting system is the same as for the interacting system. This ensures a delicate balance between the quality of the monomer and dimer finite basis set calculations. We compare the SNOOP scheme to the uncorrected and counterpoise schemes theoretically as well as numerically. Numerical results for second-order Møller-Plesset perturbation theory (MP2) and coupled-cluster with single, double, and approximate triple excitations (CCSD(T)) show that the SNOOP scheme in general outperforms the uncorrected and counterpoise approaches. Furthermore, we show that SNOOP interaction energies calculated using a given basis set are of similar quality as those determined by basis set extrapolation of counterpoise-corrected results obtained at a similar computational cost.

Kristensen, Kasper; Ettenhuber, Patrick; Eriksen, Janus Juul; Jensen, Frank; Jørgensen, Poul

2015-03-01

4

Intermolecular interactions during ultrafiltration of pegylated proteins.  

Science.gov (United States)

Recent studies have demonstrated the feasibility of using membrane ultrafiltration for the purification of pegylated proteins; however, the separations have all been performed at relatively low protein concentrations where intermolecular interactions are unimportant. The objective of this study was to examine the behavior at higher PEG concentrations and to develop an appropriate theoretical framework to describe the effects of intermolecular interactions. Ultrafiltration experiments were performed using pegylated ?-lactalbumin as a model protein with both neutral and charged composite regenerated cellulose membranes. The transmission of the pegylated ?-lactalbumin, PEG, and ?-lactalbumin all increase with increasing PEG concentration due to the increase in the solute partition coefficient arising from unfavorable intermolecular interactions in the bulk solution. The experimental results were in good agreement with a simple model that accounts for the change in Gibbs free energy associated with these intermolecular interactions, including the effects of concentration polarization on the local solute concentrations upstream of the membrane. These intermolecular interactions are shown to cause a greater than expected loss of pegylated product in a batch ultrafiltration system, and they alter the yield and purification factor that can be achieved during a diafiltration process to remove unreacted PEG. PMID:23436792

Ruanjaikaen, Krisada; Zydney, Andrew L

2013-01-01

5

Explicitly correlated intermolecular distances and interaction energies of hydrogen bonded complexes  

DEFF Research Database (Denmark)

We have optimized the lowest energy structures and calculated interaction energies for the H(2)O-H(2)O, H(2)O-H(2)S, H(2)O-NH(3), and H(2)O-PH(3) dimers with the recently developed explicitly correlated CCSD(T)-F12 methods and the associated VXZ-F12 (where X = D,T,Q) basis sets. For a given cardinal number, we find that the results obtained with the CCSD(T)-F12 methods are much closer to the CCSD(T) complete basis set limit than the conventional CCSD(T) results. In general we find that CCSD(T)-F12 results obtained with the VTZ-F12 basis set are better than the conventional CCSD(T) results obtained with an aug-cc-pV5Z basis set. We also investigate two ways to reduce the effects of basis set superposition error with conventional CCSD(T), namely, the popular counterpoise correction and limiting diffuse basis functions to the heavy atoms only. We find that for a given cardinal number, these selectively augmented correlation consistent basis sets yield results that are closer to the complete basis set limit than the corresponding fully augmented basis sets. Furthermore, we find that the difference between standard and counterpoise corrected interaction energies and intermolecular distances is reduced with the selectively augmented basis sets.

Lane, Joseph R; Kjærgaard, Henrik G

2009-01-01

6

Unrestricted absolutely localized molecular orbitals for energy decomposition analysis: Theory and applications to intermolecular interactions involving radicals  

Science.gov (United States)

Radical-closed shell and radical-radical intermolecular interactions are less well-understood than those between closed shell species. With the objective of gaining additional insight, this work reports a generalization of the absolutely localized molecular orbital (ALMO) energy decomposition analysis (EDA) to open shell fragments, described by self-consistent field methods, such as standard density functional theory. The ALMO-EDA variationally partitions an intermolecular interaction energy into three separate contributions; frozen orbital interactions, polarization, and charge transfer. The first examples involve comparison of the interactions of alkanes and alkyl radicals (methyl radical, methane, tertiary butyl radical, and isobutane) with sodium, potassium, hydronium, and ammonium cations. A second series of examples involve benzene cation interacting with a series of nucleophiles in both on-top and side-on geometries. The ALMO-EDA yields a variety of interesting insights into the relative roles of its component contributions as the interacting partners and their geometries are changed.

Horn, Paul R.; Sundstrom, Eric Jon; Baker, Thomas A.; Head-Gordon, Martin

2013-04-01

7

Local intermolecular interactions for selective CO2 capture by zeolitic imidazole frameworks: energy decomposition analysis  

International Nuclear Information System (INIS)

Intermolecular energy decomposition analysis (EDA) is reported for the binding of CO2 with zeolitic imidazole frameworks (ZIF) to provide a molecular level interpretation of the recent capacity and selectivity measurements of several ZIFs and to suggest a theoretical guideline to improve their performance further, using 1 nm size of organic linker fragment of the ZIFs as a target molecule. The EDA suggests that the local electronic interaction of CO2 and the substituent groups, mainly frozen density and polarization interactions with little charge transfer, is the primary binding interaction, but the electron correlation effects can be equally or more important depending on the binding geometry and functional groups. The present correlated calculations identify the preferred ZIF binding sites for various gases including CO2 to be mostly near the benzene substituent groups rather than the plane of imidazole rings. We predict that the NH2-substituted ZIF would have an enhanced capacity of CO2 as compared to the NO2-substituted ZIF that was recently synthesized and reported to be one of the materials with the best capacity results along with high gas selectivity. The present calculations may imply that the local functionality of the linking organics, rather than detailed framework structures, may be of primary importance in designing certain high capacity MOF or ZIF materials.F materials.

8

Rank dependence of coal physico-chemical parameters: 1. Estimation of intermolecular interaction energy by means of structural parameters  

Energy Technology Data Exchange (ETDEWEB)

The intermolecular interaction energies in coal have been estimated and the calculations involved are discussed. The intermolecular interaction energies (U{Delta}H{sub v}-RT{sub b}) between hydrocarbons of different classes have been calculated on the basis of experimental data on the standard heat of vaporization, {Delta}H{sub v}, and the boiling point, T{sub b}. Empirical formulae have been obtained for the calculation of {Delta}H{sub v} and T{sub b} as well as for the interaction energies in dimers. The structural parameters of the hydrocarbons used are as follows: molecular mass, H/C ratio, aromaticity, type of distribution of carbons, ionization potential, molar polarizability and the topological parameter, f, which is determined from the molecular structure. 22 refs., 4 figs., 4 tabs.

Krichko, A.A.; Gyul' maliev, A.M.; Gladun, T.G.; Gagarin, S.G. (Institute for Fossil Fuels, Moscow (USSR))

1991-03-01

9

Intermolecular interactions in solid benzene  

Science.gov (United States)

The lattice dynamics and molecular vibrations of benzene and deuterated benzene crystals are calculated from force constants derived from density-functional theory (DFT) calculations and compared with measured inelastic neutron-scattering spectra. A very small change (0.5%) in lattice parameter is required to obtain real lattice-mode frequencies across the Brillouin zone. There is a strong coupling between wagging and breathing modes away from the zone center. This coupling and sensitivity to cell size arises from two basic interactions. Firstly, comparatively strong interactions that hold the benzene molecules together in layers. These include an intermolecular interaction in which H atoms of one molecule link to the center of the aromatic ring of a neighboring molecule. The layers are held to each other by weaker interactions, which also have components that hold molecules together within a layer. Small changes in the lattice parameters change this second type of interaction and account for the changes to the lattice dynamics. The calculations also reveal a small auxetic effect in that elongation of the crystal along the b axis leads to an increase in internal pressure in the ac plane, that is, elongation in the b direction induces expansion in the a and c directions.

Kearley, G. J.; Johnson, M. R.; Tomkinson, J.

2006-01-01

10

Universal scaling of potential energy functions describing intermolecular interactions. II. The halide-water and alkali metal-water interactions  

Energy Technology Data Exchange (ETDEWEB)

The scaled forms of the newly introduced generalized potential energy functions (PEFs) describing intermolecular interactions [J. Chem. Phys. xx, yyyyy (2011)] have been used to fit the ab-initio minimum energy paths (MEPs) for the halide- and alkali metal-water systems X-(H2O), X=F, Cl, Br, I, and M+(H2O), M=Li, Na, K, Rb, Cs. These generalized forms produce fits to the ab-initio data that are between one and two orders of magnitude better in the ?2 than the original forms of the PEFs. They were found to describe both the long-range, minimum and repulsive wall of the potential energy surface quite well. Overall the 4-parameter extended Morse (eM) and generalized Buckingham exponential-6 (gB-e6) potentials were found to best fit the ab-initio data. Furthermore, a single set of parameters of the reduced form was found to describe all candidates within each class of interactions. The fact that in reduced coordinates a whole class of interactions can be represented by a single PEF, yields the simple relationship between the molecular parameters associated with energy (well depth, ?), structure (equilibrium distance, rm) and spectroscopy (anharmonic frequency, ?):€? = A? (? /?)1/ 2 /rm + B?? /rm 3 , where A and B are constants depending on the underlying PEF. This more general case of Badger’s rule has been validated using the experimentally measured frequencies of the hydrogen bonded OH stretching vibrations in the halide-water series.

Werhahn, Jasper C.; Akase, Dai; Xantheas, Sotiris S.

2014-08-14

11

[Analysis of intermolecular interaction energy inputs in benzene-imidazole and imidazole-imidazole systems in parallel displaced and T-configuration].  

Science.gov (United States)

Intermolecular interactions in several dimer aromatic systems were analyzed to determine how various energy contributions (electrostatic, exchange, repulsion, and polarization) change depending on the value of monomers separation. Different contributions to the intermolecular energy interactions between imidazole-imidazole and benzene-imidazole dimers are studied using the aug-cc-pVDZ basis set in the framework of ab initio Hartree-Fock and second-order Møller-Plesset perturbation theory methods. Special attention is paid to the exchange and dispersion energy binding contributions. PMID:24159814

Shchegolev, B F; McKee, M L; Zhuravlev, A V; Savvateeva-Popova, E V

2013-01-01

12

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

International Nuclear Information System (INIS)

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.

13

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

Science.gov (United States)

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.; Albernaz, Alessandra F.; Palazzetti, Federico; Lombardi, Andrea; Grossi, Gaia; Aquilanti, Vincenzo

2011-08-01

14

Predicting the sites and energies of noncovalent intermolecular interactions using local properties.  

Science.gov (United States)

Feed-forward artificial neural nets have been used to recognize H-bond donor and acceptor sites on drug-like molecules based on local properties (electron density, molecular electrostatic potential and local ionization energy, electron affinity, and polarizability) calculated at grid points around the molecule. Interaction energies for training were obtained from B97-D and ?B97X-D/aug-cc-pVDZ density-functional theory calculations on a series of model central molecules and H-bond acceptor and donor probes constrained to the grid points used for training. The resulting models provide maps of both classical and unusual H- and halogen-bonding sites. Note that these reactions result even though only classical H-bond donors and acceptors were used as probes around the central molecules. Some examples demonstrate the ability of the models to take the electronics of the central molecule into consideration and to provide semiquantitative estimates of interaction energies at low computational cost. PMID:22458324

El Kerdawy, Ahmed; Wick, Christian R; Hennemann, Matthias; Clark, Timothy

2012-04-23

15

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)

16

Intermolecular interactions as actors in energy-transfer processes in lanthanide complexes with 2,2'-bipyridine.  

Science.gov (United States)

A series of lanthanide complexes [LnCl(x)(bpy)(y)(H(2)O)(z)]Cl(3-x)(H(2)O)(n)(EtOH)(m) (Ln = Eu, Gd, Tb; x = 1, 2; y = 1, 2; z = 2-4) with different numbers of 2,2'-bipyridine (bpy), chloride ions, and water molecules in the inner coordination sphere were synthesized and investigated with the aim of relating their molecular geometry and crystal packing to the efficiency of ligand-to-metal energy transfer. In conjunction to the rotation of the pyridine rings upon coordination to the Ln ion, the high flexibility displayed by bpy ligands leads to rather unexpected bending of these rings with respect to the central bond, owing to intermolecular interactions such as Cl...pi and pi-stacking ones. Deciphering the luminescence properties of the Eu and Tb complexes needs to take into account both the composition of the inner coordination sphere and the peculiarities of the crystal packing. For instance, in addition to the classical ligand --> Eu charge-transfer state (LMCT), another charge-transfer state induced by pi-stacking interactions (SICT) could be identified. These two states, located between the singlet and triplet states of the bpy ligand(s), provide relays facilitating the energy migration from the singlet to the triplet states and eventually to the excited Eu states, improving the overall ligand-to-Eu energy transfer. Another point is the involvement of the inner-sphere water molecules in H-bonding with chloride ions, which considerably lowers their luminescence quenching ability, so that the adducts remain highly luminescent. For instance, the terbium chloride with two bpy ligands is an efficient near-UV to green light converter, with an overall quantum yield equal to 37% despite the coordinated water molecules. The interpretations given are substantiated by DFT and TD-DFT theoretical calculations of the complexes and ligand assemblies. PMID:19522489

Puntus, Lada N; Lyssenko, Konstantin A; Pekareva, Irina S; Bünzli, Jean-Claude G

2009-07-01

17

Probing intermolecular protein-protein interactions in the calcium-sensing receptor homodimer using bioluminescence resonance energy transfer (BRET)  

DEFF Research Database (Denmark)

The calcium-sensing receptor (CaR) belongs to family C of the G-protein coupled receptor superfamily. The receptor is believed to exist as a homodimer due to covalent and non-covalent interactions between the two amino terminal domains (ATDs). It is well established that agonist binding to family C receptors takes place at the ATD and that this causes the ATD dimer to twist. However, very little is known about the translation of the ATD dimer twist into G-protein coupling to the 7 transmembrane moieties (7TMs) of these receptor dimers. In this study we have attempted to delineate the agonist-induced intermolecular movements in the CaR homodimer using the new bioluminescence resonance energy transfer technique, BRET2, which is based on the transference of energy from Renilla luciferase (Rluc) to the green fluorescent protein mutant GFP2. We tagged CaR with Rluc and GFP2 at different intracellular locations. Stable and highly receptor-specific BRET signals were obtained in tsA cells transfected with Rluc- and GFP2-tagged CaRs under basal conditions, indicating that CaR is constitutively dimerized. However, the signals were not enhanced by the presence of agonist. These results could indicate that at least parts of the two 7TMs of the CaR homodimer are in close proximity in the inactivated state of the receptor and do not move much relative to one another upon agonist activation. However, we cannot exclude the possibility that the BRET technology is unable to register putative conformational changes in the CaR homodimer induced by agonist binding because of the bulk sizes of the Rluc and GFP2 molecules.

Jensen, Anders A.; Hansen, Jakob L

2002-01-01

18

Intermolecular interaction studies using small volumes.  

Science.gov (United States)

We present the use of 1-mm room-temperature probe technology to perform intermolecular interaction studies using chemical shift perturbation methods and saturation transfer difference (STD) spectroscopy using small sample volumes. The use of a small sample volume (5-10 µl) allows for an alternative titration protocol where individual samples are prepared for each titration point, rather than the usual protocol used for a 5-mm probe setup where the ligand is added consecutively to the solution containing the protein or host of interest. This allows for considerable economy in the consumption and cost of the protein and ligand amounts required for interaction studies. For titration experiments, the use of the 1-mm setup consumes less than 10% of the ligand amount required using a 5-mm setup. This is especially significant when complex ligands that are only available in limited quantities, typically because they are obtained from natural sources or through elaborate synthesis efforts, need to be investigated. While the use of smaller volumes does increase the measuring time, we demonstrate that the use of commercial small volume probes allows the study of interactions that would otherwise be impossible to address by NMR. PMID:21162136

Bourry, David; Sinnaeve, Davy; Gheysen, Katelijne; Fritzinger, Bernd; Vandenborre, Gianni; Van Damme, Els J M; Wieruszeski, Jean-Michel; Lippens, Guy; Ampe, Christophe; Martins, José C

2011-01-01

19

Small and efficient basis sets for the evaluation of accurate interaction energies: aromatic molecule-argon ground-state intermolecular potentials and rovibrational States.  

Science.gov (United States)

By evaluating a representative set of CCSD(T) ground state interaction energies for van der Waals dimers formed by aromatic molecules and the argon atom, we test the performance of the polarized basis sets of Sadlej et al. (J. Comput. Chem. 2005, 26, 145; Collect. Czech. Chem. Commun. 1988, 53, 1995) and the augmented polarization-consistent bases of Jensen (J. Chem. Phys. 2002, 117, 9234) in providing accurate intermolecular potentials for the benzene-, naphthalene-, and anthracene-argon complexes. The basis sets are extended by addition of midbond functions. As reference we consider CCSD(T) results obtained with Dunning's bases. For the benzene complex a systematic basis set study resulted in the selection of the (Z)Pol-33211 and the aug-pc-1-33321 bases to obtain the intermolecular potential energy surface. The interaction energy values and the shape of the CCSD(T)/(Z)Pol-33211 calculated potential are very close to the best available CCSD(T)/aug-cc-pVTZ-33211 potential with the former basis set being considerably smaller. The corresponding differences for the CCSD(T)/aug-pc-1-33321 potential are larger. In the case of the naphthalene-argon complex, following a similar study, we selected the (Z)Pol-3322 and aug-pc-1-333221 bases. The potentials show four symmetric absolute minima with energies of -483.2 cm(-1) for the (Z)Pol-3322 and -486.7 cm(-1) for the aug-pc-1-333221 basis set. To further check the performance of the selected basis sets, we evaluate intermolecular bound states of the complexes. The differences between calculated vibrational levels using the CCSD(T)/(Z)Pol-33211 and CCSD(T)/aug-cc-pVTZ-33211 benzene-argon potentials are small and for the lowest energy levels do not exceed 0.70 cm(-1). Such differences are substantially larger for the CCSD(T)/aug-pc-1-33321 calculated potential. For naphthalene-argon, bound state calculations demonstrate that the (Z)Pol-3322 and aug-pc-1-333221 potentials are of similar quality. The results show that these surfaces differ substantially from the available MP2/aug-cc-pVDZ potential. For the anthracene-argon complex it proved advantageous to calculate interaction energies by using the (Z)Pol and the aug-pc-1 basis sets, and we expect it to be increasingly so for complexes containing larger aromatic molecules. PMID:25317989

Cybulski, Hubert; Baranowska-??czkowska, Angelika; Henriksen, Christian; Fernández, Berta

2014-11-01

20

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

21

Universal scaling of potential energy functions describing intermolecular interactions. I. Foundations and scalable forms of new generalized Mie, Lennard-Jones, Morse, and Buckingham exponential-6 potentials  

Energy Technology Data Exchange (ETDEWEB)

Based on the formulation of the analytical expression of the potential V(r) describing intermolecular interactions in terms of the dimensionless variables r*=r/rm and !*=V/!, where rm is the separation at the minimum and ! the well depth, we propose more generalized scalable forms for the commonly used Lennard-Jones, Mie, Morse and Buckingham exponential-6 potential energy functions (PEFs). These new generalized forms have an additional parameter from and revert to the original ones for some choice of that parameter. In this respect, the original forms can be considered as special cases of the more general forms that are introduced. We also propose a scalable, but nonrevertible to the original one, 4-parameter extended Morse potential.

Xantheas, Sotiris S.; Werhahn, Jasper C.

2014-08-14

22

Accurate Calculations of Intermolecular Interaction Energies Using Explicitly Correlated Coupled Cluster Wave Functions and a Dispersion-Weighted MP2 Method  

Science.gov (United States)

Explicitly correlated coupled-cluster calculations of intermolecular interaction energies for the S22 benchmark set of Jure?ka, \\vsponer, ?erný, and Hobza (Chem. Phys. Phys. Chem. 2006, 8, 1985) are presented. Results obtained with the recently proposed CCSD(T)-F12a method and augmented double-? basis sets are found to be in very close agreement with basis set extrapolated conventional CCSD(T) results. Furthermore, we propose a dispersion-weighted MP2 (DW-MP2) approximation that combines the good accuracy of MP2 for complexes with predominately electrostatic bonding and SCS-MP2 for dispersion-dominated ones. The MP2-F12 and SCS-MP2-F12 correlation energies are weighted by a switching function that depends on the relative HF and correlation contributions to the interaction energy. For the S22 set, this yields a mean absolute deviation of 0.2 kcal/mol from the CCSD(T)-F12a results. The method, which allows obtaining accurate results at low cost, is also tested for a number of dimers that are not in the training set.

Marchetti, Oliver; Werner, Hans-Joachim

2009-10-01

23

Studies of pilocarpine:carbomer intermolecular interactions.  

Science.gov (United States)

The interactions between pilocarpine (PIL) and the anionic polyelectrolyte carbomer (CBR) were investigated. The effects of the chemical interactions on the chemical stability of the drug also were evaluated. The binary system was characterized by nuclear magnetic resonance techniques, Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction, scanning electron microscopy (SEM) and thermal analysis. The experiments showed that the complex, prepared by freeze-drying, is a solid amorphous form different from its precursors, thereby offering an interesting alternative for the preparation of extended release matrices. The solution stability of PIL was studied at pH 7 and 8, at 70 °C. The PIL solution stability was evaluated alone and in the presence of CBR. Results indicated that the drug in the presence of the polymer is 3.3 and 3.5 times more stable, at pH 7 and pH 8, respectively, than the drug without CBR. The activation energy and the frequency factor, according to Arrhenius plot, were estimated to be 13.9 ± 0.4 and 14.8 ± 0.5 kcalmol(-1), and 6.1 ± 0.3 and 7.6 ± 0.3, with and without the polymer, respectively. PMID:22349054

Zoppi, Ariana; Linck, Yamila Garro; Monti, Gustavo A; Genovese, Diego B; Jimenez Kairuz, Alvaro F; Manzo, Rubén H; Longhi, Marcela R

2012-05-10

24

Weak intermolecular interactions in gas-phase NMR  

OpenAIRE

Gas-phase NMR spectra demonstrating the effect of weak intermolecular forces on the NMR shielding constants of the interacting species are reported. We analyse the interaction of the molecular hydrogen isotopomers with He, Ne, and Ar, and the interaction in the He-CO_2 dimer. The same effects are studied for all these systems in the ab initio calculations. The comparison of the experimental and computed shielding constants is shown to depend strongly on the treatment of the ...

Garbacz, Piotr; Piszczatowski, Konrad; Jackowski, Karol; Moszynski, Robert; Jaszunski, Michal

2011-01-01

25

Switching intermolecular interactions by confinement in carbon nanotubes.  

Science.gov (United States)

The encapsulation of trityl-functionalised C60 molecules inside carbon nanotubes drastically affects the intermolecular interactions for this species. Whilst the orientations of molecules in the crystal are often controlled by thermodynamics, the molecular orientations in nanotubes are a result of kinetic control imposed by the mechanism of entry into and encapsulation within the nanotube. PMID:25415311

Chamberlain, T W; Lebedeva, M A; Abuajwa, W; Suyetin, M; Lewis, W; Bichoutskaia, E; Schröder, M; Khlobystov, A N

2015-01-14

26

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-? 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 A?, 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

27

Weak intermolecular interactions in gas-phase nuclear magnetic resonance.  

Science.gov (United States)

Gas-phase nuclear magnetic resonance (NMR) spectra demonstrating the effect of weak intermolecular forces on the NMR shielding constants of the interacting species are reported. We analyse the interaction of the molecular hydrogen isotopomers with He, Ne, and Ar, and the interaction in the He-CO(2) dimer. The same effects are studied for all these systems in the ab initio calculations. The comparison of the experimental and computed shielding constants is shown to depend strongly on the treatment of the bulk susceptibility effects, which determine in practice the pressure dependence of the experimental values. Best agreement of the results is obtained when the bulk susceptibility correction in rare gas solvents is evaluated from the analysis of the He-rare gas interactions, and when the shielding of deuterium in D(2)-rare gas systems is considered. PMID:21895188

Garbacz, Piotr; Piszczatowski, Konrad; Jackowski, Karol; Moszynski, Robert; Jaszu?ski, Micha?

2011-08-28

28

Weak intermolecular interactions in gas-phase NMR  

CERN Document Server

Gas-phase NMR spectra demonstrating the effect of weak intermolecular forces on the NMR shielding constants of the interacting species are reported. We analyse the interaction of the molecular hydrogen isotopomers with He, Ne, and Ar, and the interaction in the He-CO_2 dimer. The same effects are studied for all these systems in the ab initio calculations. The comparison of the experimental and computed shielding constants is shown to depend strongly on the treatment of the bulk susceptibility effects, which determine in practice the pressure dependence of the experimental values. Best agreement of the results is obtained when the bulk susceptibility correction in rare gas solvents is evaluated from the analysis of the He-rare gas interactions, and when the shielding of deuterium in D_2-rare gas systems is considered.

Garbacz, Piotr; Jackowski, Karol; Moszynski, Robert; Jaszunski, Michal

2011-01-01

29

Distinguishability and chiral stability in solution: Effects of decoherence and intermolecular interactions  

Energy Technology Data Exchange (ETDEWEB)

We examine the effect of decoherence and intermolecular interactions (chiral discrimination energies) on the chiral stability and the distinguishability of initially pure versus mixed states in an open chiral system. Under a two-level approximation for a system, intermolecular interactions are introduced by a mean-field theory, and interaction between a system and an environment is modeled by a continuous measurement of a population difference between the two chiral states. The resultant equations are explored for various parameters, with emphasis on the combined effects of the initial condition of the system, the chiral discrimination energies, and the decoherence in determining: the distinguishability as measured by a population difference between the initially pure and mixed states, and the decoherence process; the chiral stability as measured by the purity decay; and the stationary state of the system at times long relative to the time scales of the system dynamics and of the environmental effects.

Han, Heekyung [Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario M5T 3M7 (Canada); Wardlaw, David M., E-mail: dwardlaw@mun.ca [Department of Chemistry, Memorial University of Newfoundland, St. John' s, Newfoundland and Labrador A1C 5S7 (Canada); Frolov, Alexei M., E-mail: afrolov@uwo.ca [Department of Applied Mathematics, University of Western Ontario, London, Ontario N6H 5B7 (Canada)

2014-05-28

30

Distinguishability and chiral stability in solution: Effects of decoherence and intermolecular interactions  

International Nuclear Information System (INIS)

We examine the effect of decoherence and intermolecular interactions (chiral discrimination energies) on the chiral stability and the distinguishability of initially pure versus mixed states in an open chiral system. Under a two-level approximation for a system, intermolecular interactions are introduced by a mean-field theory, and interaction between a system and an environment is modeled by a continuous measurement of a population difference between the two chiral states. The resultant equations are explored for various parameters, with emphasis on the combined effects of the initial condition of the system, the chiral discrimination energies, and the decoherence in determining: the distinguishability as measured by a population difference between the initially pure and mixed states, and the decoherence process; the chiral stability as measured by the purity decay; and the stationary state of the system at times long relative to the time scales of the system dynamics and of the environmental effects

31

Long range intermolecular interactions between the alkali diatomics Na(2), K(2), and NaK.  

Science.gov (United States)

Long range interactions between the ground state alkali diatomics Na(2)-Na(2), K(2)-K(2), Na(2)-K(2), and NaK-NaK are examined. Interaction energies are first determined from ab initio calculations at the coupled-cluster with singles, doubles, and perturbative triples [CCSD(T)] level of theory, including counterpoise corrections. Long range energies calculated from diatomic molecular properties (polarizabilities and dipole and quadrupole moments) are then compared with the ab initio energies. A simple asymptotic model potential E(LR)=E(elec)+E(disp)+E(ind) is shown to accurately represent the intermolecular interactions for these systems at long range. PMID:20590191

Zemke, Warren T; Byrd, Jason N; Michels, H Harvey; Montgomery, John A; Stwalley, William C

2010-06-28

32

Control of emission by intermolecular fluorescence resonance energy transfer and intermolecular charge transfer.  

Science.gov (United States)

Control of emission by intermolecular fluorescence resonant energy transfer (IFRET) and intermolecular charge transfer (ICT) is investigated with the quantum-chemistry method using two-dimensional (2D) and three-dimensional (3D) real space analysis methods. The work is based on the experiment of tunable emission from doped 1,3,5-triphenyl-2-pyrazoline (TPP) organic nanoparticles (Peng, A. D.; et al. Adv. Mater. 2005, 17, 2070). First, the excited-state properties of the molecules, which are studied (TPP and DCM) in that experiment, are investigated theoretically. The results of the 2D site representation reveal the electron-hole coherence and delocalization size on the excitation. The results of 3D cube representation analysis reveal the orientation and strength of the transition dipole moments and intramolecular or intermolecular charge transfer. Second, the photochemical quenching mechanism via IFRET is studied (here "resonance" means that the absorption spectrum of TPP overlaps with the fluorescence emission spectrum of DCM in the doping system) by comparing the orbital energies of the HOMO (highest occupied molecular orbital) and the LUMO (lowest unoccupied molecular orbital) of DCM and TPP in absorption and fluorescence. Third, for the DCM-TPP complex, the nonphotochemical quenching mechanism via ICT is investigated. The theoretical results show that the energetically lowest ICT state corresponds to a pure HOMO-LUMO transition, where the densities of the HOMO and LUMO are strictly located on the DCM and TPP moieties, respectively. Thus, the lowest ICT state corresponds to an excitation of an electron from the HOMO of DCM to the LUMO of TPP. PMID:16686468

Sun, Mengtao; Pullerits, Tõnu; Kjellberg, Pär; Beenken, Wichard J D; Han, Keli

2006-05-18

33

Vacuolar H(+)-ATPases: intra- and intermolecular interactions.  

Science.gov (United States)

V-ATPases in eukaryotes are heteromultimeric, H(+)-transporting proteins. They are localized in a multitude of different membranes and energize many different transport processes. Unique features of V-ATPases are, on the one hand, their ability to regulate enzymatic and ion transporting activity by the reversible dissociation of the catalytic V(1) complex from the membrane bound proton translocating V(0) complex and, on the other hand, their high sensitivity to specific macrolides such as bafilomycin and concanamycin from streptomycetes or archazolid and apicularen from myxomycetes. Both features require distinct intramolecular as well as intermolecular interactions. Here we will summarize our own results together with newer developments in both of these research areas. PMID:21640428

Huss, Markus; Vitavska, Olga; Albertmelcher, Andrea; Bockelmann, Svenja; Nardmann, Christin; Tabke, Katharina; Tiburcy, Felix; Wieczorek, Helmut

2011-09-01

34

Evolutionary meandering of intermolecular interactions along the drift barrier.  

Science.gov (United States)

Many cellular functions depend on highly specific intermolecular interactions, for example transcription factors and their DNA binding sites, microRNAs and their RNA binding sites, the interfaces between heterodimeric protein molecules, the stems in RNA molecules, and kinases and their response regulators in signal-transduction systems. Despite the need for complementarity between interacting partners, such pairwise systems seem to be capable of high levels of evolutionary divergence, even when subject to strong selection. Such behavior is a consequence of the diminishing advantages of increasing binding affinity between partners, the multiplicity of evolutionary pathways between selectively equivalent alternatives, and the stochastic nature of evolutionary processes. Because mutation pressure toward reduced affinity conflicts with selective pressure for greater interaction, situations can arise in which the expected distribution of the degree of matching between interacting partners is bimodal, even in the face of constant selection. Although biomolecules with larger numbers of interacting partners are subject to increased levels of evolutionary conservation, their more numerous partners need not converge on a single sequence motif or be increasingly constrained in more complex systems. These results suggest that most phylogenetic differences in the sequences of binding interfaces are not the result of adaptive fine tuning but a simple consequence of random genetic drift. PMID:25535374

Lynch, Michael; Hagner, Kyle

2015-01-01

35

Ab initio investigation of intermolecular interactions in solid benzene  

CERN Document Server

A computational strategy for the evaluation of the crystal lattice constants and cohesive energy of the weakly bound molecular solids is proposed. The strategy is based on the high level ab initio coupled-cluster determination of the pairwise additive contribution to the interaction energy. The zero-point-energy correction and non-additive contributions to the interaction energy are treated using density functional methods. The experimental crystal lattice constants of the solid benzene are reproduced, and the value of 480 meV/molecule is calculated for its cohesive energy.

Bludsky, O; Soldan, P; 10.1103/PhysRevB.77.092103

2009-01-01

36

Intermolecular potential energy surfaces for the interaction between H2X (Xdbnd O, S) and a metastable Ne*(3P2,0) atom  

Science.gov (United States)

Potential energy surfaces for the interaction of a Ne*(3P2,0) atom with H2O and H2S molecules are obtained on the basis of a semi empirical method that has been previously used for some specific orientations in Ne*(3P2,0)-H2O system. The method is now suitable for all orientations and also for Ne*(3P2,0)-H2S system. Interesting features emerge by comparing the two systems and appear related to different characteristics of the two molecular partners. The potential energy surface for Ne*(3P2,0)-H2S has been also successfully tested for reproducing recent experimental Penning ionization electron spectroscopy data, sensible to some specific orientations of the two colliding partners.

Falcinelli, Stefano; Bartocci, Alessio; Candori, Pietro; Pirani, Fernando; Vecchiocattivi, Franco

2014-10-01

37

About intermolecular interactions in binary and ternary solutions of some azo-benzene derivatives.  

Science.gov (United States)

The nature and strength of the intermolecular interactions in the solutions of three azo-benzene derivatives (ADi, i=1, 2, 3) were established by solvatochromic effects in solvents with different electric permittivities, refractive indices and Kamlet-Taft constants. A quantum mechanical analysis corroborated with spectral data offered information about the excited state dipole moments and polarizabilities of the studied compounds. The separation of the supply of universal and specific interactions to the total spectral shift was made based on the regression coefficients from the equations describing the solvatochromic effect. Supplementary information about the composition of the first solvation shell and the energy in the solute-solvent molecular pairs were obtained analyzing the ternary solutions of ADi, i=1, 2, 3 compounds in solvent mixture Methanol (M)+n-Hexane (H). PMID:25168003

Ivan, Liliana Mihaela; Closca, Valentina; Burlea, Marin; Rusu, Elena; Airinei, Anton; Dorohoi, Dana Ortansa

2015-02-01

38

About intermolecular interactions in binary and ternary solutions of some azo-benzene derivatives  

Science.gov (United States)

The nature and strength of the intermolecular interactions in the solutions of three azo-benzene derivatives (ADi, i = 1, 2, 3) were established by solvatochromic effects in solvents with different electric permittivities, refractive indices and Kamlet-Taft constants. A quantum mechanical analysis corroborated with spectral data offered information about the excited state dipole moments and polarizabilities of the studied compounds. The separation of the supply of universal and specific interactions to the total spectral shift was made based on the regression coefficients from the equations describing the solvatochromic effect. Supplementary information about the composition of the first solvation shell and the energy in the solute-solvent molecular pairs were obtained analyzing the ternary solutions of ADi, i = 1, 2, 3 compounds in solvent mixture Methanol (M) + n-Hexane (H).

Ivan, Liliana Mihaela; Closca, Valentina; Burlea, Marin; Rusu, Elena; Airinei, Anton; Dorohoi, Dana Ortansa

2015-02-01

39

Reversible electron-induced cis-trans isomerization mediated by intermolecular interactions  

International Nuclear Information System (INIS)

Reversible isomerization processes are rarely found when organic molecular switches are adsorbed on metal surfaces. One obstacle is the large energy difference of the isomeric forms, since usually the most planar conformer has the largest adsorption energy. In the example of an imine derivative, we show a strategy for also stabilizing the non-planar isomer by intermolecular bonding to its neighbors. Tunneling electrons from the tip of a scanning tunneling microscope can then be used to induce reversible switching between the trans and cis-like state. Supported by model force-field calculations, we illustrate that the most probable cause of the enhanced stability of the three-dimensional cis state at specific adsorption sites is the electrostatic interaction with N sites of the neighboring molecule.

40

Characterization of intermolecular interaction between two substances when one substance does not possess any characteristic peak  

Science.gov (United States)

We explore whether it is possible to use 2D correlation spectrum to characterize intermolecular interactions between two solutes dissolved in the same solution when one substance does not possesses any characteristic peak. We demonstrate that the interaction can be manifested by characteristic cross peaks in 2D asynchronous correlated spectrum. The above cross peaks reflect the subtle spectral variations on the characteristic peak of another solute under intermolecular interaction. On the other hand, 2D synchronous spectrum is not suitable to characterize intermolecular interaction since the cross peaks contain irremovable interfering parts. The terbium-chloride/benzamide/methanol system is used to demonstrate that this approach is applicable in the real chemical system.

Li, Xiaopei; Fan, Xiaokun; Huang, Kun; Liu, Huizhou; Zhao, Ying; Wei, Yongju; Liu, Cuige; Xu, Yizhuang; Noda, Isao; Wu, Jinguang

2014-07-01

41

On the effect of a radiation field in modifying the intermolecular interaction between two chiral molecules  

International Nuclear Information System (INIS)

The change in the mutual energy of interaction between a pair of chiral molecules coupled via the exchange of a single virtual photon and in the presence of an electromagnetic field is calculated using nonrelativistic quantum electrodynamics. The particular viewpoint adopted is one that has an intuitive physical appeal and resembles a classical treatment. It involves the coupling of electric and magnetic dipole moments induced at each center by the incident radiation field to the resonant dipole-dipole interaction tensor. The energy shift is evaluated for fixed as well as random orientations of the molecular pair with respect to the direction of propagation of the field. A complete polarization analysis is carried out for the former situation by examining the effect of incident radiation that is linearly or circularly polarized and traveling in a direction that is parallel or perpendicular to the intermolecular distance vector. After tumble averaging, all polarization dependence of the energy shift vanishes. In both cases the interaction energy is directly proportional to the irradiance of the applied field, and is discriminatory, changing sign when one optically active species is replaced by its enantiomer. The asymptotic behavior of the energy shift at the limits of large and small separations is also studied

42

Potential functions for describing intermolecular interactions in cyanoacetylene clusters  

Science.gov (United States)

Potential functions for describing interactions between cyanoacetylene molecules based on ab initio determined molecular properties and IMPT calculations are proposed. Electrostatic interactions are described by a multipole expansion on atoms and midbond points; dispersion is expressed by a London-type function of atomic polarizabilities and induction is considered via a series of polarizabilities distributed over the atoms. The repulsion contribution was determined by using a test-particle model involving a helium atom as probe particle. Two functions based on two basis sets of different size, viz. 6-311G** and 5S4P2D/3S2P, were used. Cyanoacetylene dimer exhibits two minima corresponding to a linear and an antiparallel configuration, respectively. The proposed functions accurately reproduce the characteristics of the dimer minima as derived from ab initio calculations at the Møller-Plesset (MP2) level. In addition, they can describe cooperativeness in larger clusters; specifically, the dipole moment and interaction energy per molecule increase with increasing number of constituent units in the cluster. The behavior observed is similar to previously reported findings for HCN clusters.

Cabaleiro-Lago, Enrique M.; Ríos, Miguel A.

1998-11-01

43

Intermolecular interactions in mixtures of ethyl formate with methanol, ethanol, and 1-propanol on density, viscosity, and ultrasonic data  

Science.gov (United States)

Density (?), viscosity (?), and ultrasonic velocity ( U) have been measured for binary mixtures of ethyl formate with methanol, ethanol, and 1-propanol at 303 K. From the experimental data, adiabatic compressibility (?), acoustic impedance ( Z), viscous relaxation time (?), free length ( L f), free volume ( V f), internal pressure (?i), and Gibbs free energy (? G) have been deduced. It is shown that strength of intermolecular interactions between ethyl formate with selected 1-alcohols were in the order of methanol 1-propanol.

Elangovan, S.; Mullainathan, S.

2014-12-01

44

Isolating the non-polar contributions to the intermolecular potential for water-alkane interactions  

Science.gov (United States)

Intermolecular potential models for water and alkanes describe pure component properties fairly well, but fail to reproduce properties of water-alkane mixtures. Understanding interactions between water and non-polar molecules like alkanes is important not only for the hydrocarbon industry but has implications to biological processes as well. Although non-polar solutes in water have been widely studied, much less work has focused on water in non-polar solvents. In this study we calculate the solubility of water in different alkanes (methane to dodecane) at ambient conditions where the water content in alkanes is very low so that the non-polar water-alkane interactions determine solubility. Only the alkane-rich phase is simulated since the fugacity of water in the water rich phase is calculated from an accurate equation of state. Using the SPC/E model for water and TraPPE model for alkanes along with Lorentz-Berthelot mixing rules for the cross parameters produces a water solubility that is an order of magnitude lower than the experimental value. It is found that an effective water Lennard-Jones energy ?W/k = 220 K is required to match the experimental water solubility in TraPPE alkanes. This number is much higher than used in most simulation water models (SPC/E—?W/k = 78.2 K). It is surprising that the interaction energy obtained here is also higher than the water-alkane interaction energy predicted by studies on solubility of alkanes in water. The reason for this high water-alkane interaction energy is not completely understood. Some factors that might contribute to the large interaction energy, such as polarizability of alkanes, octupole moment of methane, and clustering of water at low concentrations in alkanes, are examined. It is found that, though important, these factors do not completely explain the anomalously strong attraction between alkanes and water observed experimentally.

Ballal, Deepti; Venkataraman, Pradeep; Fouad, Wael A.; Cox, Kenneth R.; Chapman, Walter G.

2014-08-01

45

Ab initio ground state phenylacetylene-argon intermolecular potential energy surface and rovibrational spectrum  

DEFF Research Database (Denmark)

We evaluate the phenylacetylene-argon intermolecular potential energy surface by fitting a representative number of ab initio interaction energies to an analytic function. These energies are calculated at a grid of intermolecular geometries, using the CCSD(T) method and the aug-cc-pVDZ basis set extended with a series of 3s3p2d1flg midbond functions. The potential is characterized by two equivalent global minima where the Ar atom is located above and below the phenylacetylene plane at a distance of 3.5781 angstrom from the molecular center of mass and at an angle of 9.08 degrees with respect to the axis perpendicular to the phenylacetylene plane and containing the center of mass. The calculated interaction energy is -418.9 cm(-1). To check further the potential, we obtain the rovibrational spectrum of the complex and the results are compared to the available experimental data. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4742153

Cybulski, Hubert; Fernandez, Berta

2012-01-01

46

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

International Nuclear Information System (INIS)

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

47

Dimensionality of intermolecular interactions in layered crystals by electronic-structure theory and geometric analysis.  

Science.gov (United States)

Two-dimensional (2D) and layered structures gained a lot of attention in the recent years ("post-graphene era"). The chalcogen cyanides S(CN)(2) and Se(CN)(2) offer themselves as interesting model systems to study layered inorganic crystal structures; both are built up from cyanide molecules connected by chalcogen bonds (ChBs). Here, we investigate ChBs and their cooperativity directly within the layers of the S(CN)(2) and Se(CN)(2) crystal structures and, furthermore, in putative O(CN)(2) and Te(CN)(2) crystal structures derived therefrom. Moreover, we determine the energetic contributions of ChBs within the layers to the overall stabilization energy. To compare these structures not only energetically but also geometrically, we derive a direction-dependent root mean square of the Cartesian displacement, a possible tool for further computational investigations of layered compounds. The molecular chains connected by ChBs are highly cooperative but do not influence each other when combined to layers: the ChBs are nearly orthogonal in terms of energy when connected to the same chalcogen acceptor atom. Layers built up from ChBs account for 41% to 79% of the overall interaction energy in the crystal. This provides new, fundamental insight into the meaning of ChBs, and therefore directed intermolecular interactions, for the stability of crystal structures. PMID:25363246

George, Janine; Deringer, Volker L; Dronskowski, Richard

2015-02-01

48

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

Energy Technology Data Exchange (ETDEWEB)

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.

Yin, Chih-Chien; Li, Arvin Huang-Te; Chao, Sheng D., E-mail: sdchao@spring.iam.ntu.edu.tw [Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan (China)

2013-11-21

49

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

50

Intermolecular interactions in N-(ferrocenylmethyl)anthracene-9-carboxamide.  

Science.gov (United States)

The title compound, [Fe(C(5)H(5))(C(21)H(16)NO)], was synthesized from the coupling reaction of anthracene-9-carboxylic acid and ferrocenylmethylamine. The ferrocenyl (Fc) group and the anthracene ring system both lie approximately orthogonal to the amide moiety. An amide-amide interaction (along the a axis) is the principal interaction [N.O = 2.910 (2) A]. A C-H.pi(arene) interaction [C.centroid = 3.573 (2) A] and a C-H.O interaction [C.O = 3.275 (3) A] complete the hydrogen bonding; two short (Fc)C.C(anthracene) contacts are also present. PMID:14671357

Gallagher, John F; Kelly, Paula N; Kenny, Peter T M; Lough, Alan J

2003-12-01

51

Intermolecular interactions in N-(ferrocenylmethyl)anthracene-9-carboxamide  

OpenAIRE

The title compound, [Fe(C?H?)(C??H??NO)], was synthesized from the coupling reaction of anthracene-9-carboxylic acid and ferrocenylmethylamine. The ferrocenyl (Fc) group and the anthracene ring system both lie approximately orthogonal to the amide moiety. An amide-amide interaction (along the a axis) is the principal interaction [N...O = 2.910 (2) Å]. A C-H...?(arene) interaction [C...centroid = 3.573 (2) Å] and a C-H...O interaction [C...O = 3.275 (3) Å] complete ...

Gallagher, John F.; Kelly, Paula N.; Kenny, Peter T. M.; Lough, Alan J.

2003-01-01

52

Intermolecular interaction of prednisolone with bovine serum albumin: Spectroscopic and molecular docking methods  

Science.gov (United States)

The intermolecular interaction of prednisolone with bovine serum albumin (BSA) was studied using fluorescence, circular dichroism (CD) and molecular docking methods. The experimental results showed that the fluorescence quenching of the BSA at 338 nm by prednisolone resulted from the formation of prednisolone-BSA complex. The number of binding sites (n) for prednisolone binding on BSA was approximately equal to 1. Base on the sign and magnitude of the enthalpy and entropy changes (?H0 = -149.6 kJ mol-1 and ?S0 = -370.7 J mol-1 K-1) and the results of molecular docking, it could be suggested that the interaction forces were mainly Van der Waals and hydrogen bonding interactions. Moreover, in the binding process of BSA with prednisolone, prednisolone molecule can be inserted into the hydrophobic cavity of subdomain IIIA (site II) of BSA. The distance between prednisolone and Trp residue of BSA was calculated as 2.264 nm according to Forster's non-radiative energy transfer theory.

Shi, Jie-hua; Zhu, Ying-Yao; Wang, Jing; Chen, Jun; Shen, Ya-Jing

2013-02-01

53

Helping Students Assess the Relative Importance of Different Intermolecular Interactions  

Science.gov (United States)

A semi-quantitative model has been developed to estimate the relative effects of dispersion, dipole-dipole interactions, and H-bonding on the normal boiling points ("T[subscript b]") for a subset of simple organic systems. The model is based upon a statistical analysis using multiple linear regression on a series of straight-chain organic…

Jasien, Paul G.

2008-01-01

54

The anisole--ammonia complex: Marks of the intermolecular interactions  

Science.gov (United States)

We report an experimental study, supported by classical and quantum calculations, of the anisole-ammonia jet cooled complex. The origin band of the S 1 ? S 0 electronic transition is red shifted with respect to the corresponding band for the bare anisole molecule. From the simulation of the origin band rotational contour and the results of quantum mechanical calculations, we have been able to determine the non-planar structure of the complex. The ammonia molecule is bonded to anisole via two hydrogen bonds: one in which the nitrogen lone pair interacts with the hydrogen atoms of the methoxy group; the other involving the ammonia hydrogen atoms and the ?-electron density of the aromatic ring.

Piani, Giovanni; Pasquini, Massimiliano; Pietraperzia, Giangaetano; Becucci, Maurizio; Armentano, Antonio; Castellucci, Emilio

2007-01-01

55

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

56

Intermolecular Interaction in the Binary Mixture of valine with Water at 303.15 K  

Directory of Open Access Journals (Sweden)

Full Text Available The ultrasonic velocity (u, density (? and viscosity (? have been measured at 2 MHz frequency in the binary mixtures of valine with water over entire range concentration at 303.15 K using ultrasonic interferometer technique. The experimental data have been used to calculate acoustical parameter namely adiabatic compressibility (?a, acoustic impedance (z, intermolecular free length (Lf and relative association (RA with a view to investigate the nature and strength of molecular interaction in the binary liquid mixture. The obtained result support the occurrence of complex formation through intermolecular hydrogen bonding in there binary liquid mixtures and further used to interpret the hydrophilic part of the solute and molecular interactions in the solutions.

S.Mirikar

2014-12-01

57

Ferroelectric ordering in chiral smectic C^* liquid crystals determined by nonchiral intermolecular interactions  

OpenAIRE

General microscopic mechanism of ferroelectric ordering in chiral smectic C* liquid crystals is considered. It is shown that if the mesogenic molecules have a sufficiently low symmetry, the spontaneous polarization is proportional to one of the biaxial vector order parameters of the smectic C phase. This order parameter may be determined by intermolecular interactions which are not sensitive to molecular chirality. At the same time, the polarization is also proportional to a...

Osipov, M. A.; Gorkunov, M. V.

2007-01-01

58

Intermolecular Interactions in Dye-Sensitized Solar Cells: A Computational Modeling Perspective  

OpenAIRE

We present a unified overview of our recent activity on the modeling of relevant intermolecular interactions occurring in dye-sensitized solar cells (DSCs). The DSC is an inherent complex system, whose efficiency is essentially determined by the interrelated phenomena occurring at the multiple molecular?semiconductor?electrolyte heterointerfaces. In this Perspective, we illustrate the basic methodology and selected applications of computational modeling of dye?dye and dye...

Pastore, Mariachiara; Angelis, Filippo

2013-01-01

59

1H NMR study on the intermolecular interactions of macrocyclic and single ?-amino acids  

Science.gov (United States)

Through analysis of 1H NMR spectra, evidence was found for intermolecular interactions between macrocyclic amino acid derivatives from L-tyrosine and their importance in the formation of aggregates in solution. It was also shown that both macrocyclic and simple amino acids are capable of retaining alcohol molecules through hydrogen bonding, where the alcohol molecule acts as a proton donor and the amino group acts as an acceptor.

Quevedo, Rodolfo; Pabón, Laura; Quevedo-Acosta, Yovanny

2013-06-01

60

NMR in Van Vleck magnetics and intermolecular interactions in molecular crystals and Chevrel phases  

International Nuclear Information System (INIS)

Aspects of orbital paramagnetism and intermolecular interactions are discussed in relation to compounds containing octahedral MF6 molecules (where M is a transition metal) and Chevrel phase cuboctahedron systems M6 X8. The 100th anniversary of the birth of Professor S A Altshuler, a pioneer in the use of NMR for studying Van Vleck magnetism, is a motivation for this review. (reviews of topical problems)

61

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

Energy Technology Data Exchange (ETDEWEB)

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){sub 4}] layers to form a solid of formula unit T(ImD){sub 2}[Ni(CN){sub 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){sub 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. - Graphical abstract: In the interlayers region imidazole derivative molecules are oriented according to their dipolar and quadrupolar interactions and minimizing the steric impediment. Highlights: • Imidazole derivatives intercalation compounds. • Intermolecular interaction between intercalated imidazole derivatives. • Hybrid inorganic–organic solids. • Pi–pi interactions and ferromagnetic coupling. • Dipolar and quadrupolar interactions between intercalated imidazole derivatives.

González, M.; Lemus-Santana, A.A. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico); Rodríguez-Hernández, J. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico); Instituto de Ciencia y Tecnología de Materiales, Universidad de La Habana, Havana (Cuba); Aguirre-Velez, C.I. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico); Knobel, M. [Institute of Physics “Gleb Wataghin”, UNICAMP, 13083-970 Campinas, SP (Brazil); Reguera, E., E-mail: edilso.reguera@gmail.com [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, México, DF (Mexico)

2013-08-15

62

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

International Nuclear Information System (INIS)

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. - Graphical abstract: In the interlayers region imidazole derivative molecules are oriented according to their dipolar and quadrupolar interactions and minimizing the steric impediment. Highlights: • Imidazole derivatives intercalation compounds. • Intermolecular interaction between intercalated imidazole derivatives. • Hybrid inorganic–organic solids. • Pi–pi interactions and ferromagnetic coupling. • Dipolar and quadrupolar interactions between intercalated imidazole derivatives

63

Electron-phonon interactions and intra- and intermolecular charge mobility in the monocations of annulenes.  

Science.gov (United States)

Possible electron pairing in pi-conjugated positively charged annulenes such as (CH)(18) (18an) and (CH)(30) (30an) is studied and compared with that in the positively charged acenes. The total electron-phonon coupling constants in the monocations (l(HOMO)) for 18an and 30an are estimated. The E(2g) modes of 1611 and 1201 cm(-1) most strongly couple to the highest occupied molecular orbitals (HOMO) in 18an and 30an, respectively. The l(HOMO) values for annulenes are larger than those for acenes. The phase pattern difference between the HOMO of acenes localized on the edge part of carbon atoms and the delocalized HOMO of annulenes is the main reason for the calculated results. In view of the calculated results of the l(HOMO) values, intramolecular electron mobility (sigma(intra,HOMO)), and the reorganization energies (RE(HOMO)) in the positively charged molecules, the monocations of annulenes cannot easily become good conductors compared with the monocations of acenes, but the condition of the attractive electron-electron interactions is realized more easily in the monocations of annulenes than in the monocations of acenes. The hypothetical intramolecular supercurrent originating from both intramolecular and intermolecular vibrations in the monocations of annulenes and acenes in a case where the distance between two adjacent molecules is too large for the molecular crystal to become normal metallic state, is also discussed. PMID:16970433

Kato, Takashi; Yamabe, Tokio

2006-09-21

64

An intermolecular electrostatic interaction controls the prepore-to-pore transition in a cholesterol-dependent cytolysin.  

Science.gov (United States)

?-Barrel pore-forming toxins (?PFTs) form an obligatory oligomeric prepore intermediate before the formation of the ?-barrel pore. The molecular components that control the critical prepore-to-pore transition remain unknown for ?PFTs. Using the archetype ?PFT perfringolysin O, we show that E183 of each monomer within the prepore complex forms an intermolecular electrostatic interaction with K336 of the adjacent monomer on completion of the prepore complex. The signal generated throughout the prepore complex by this interaction irrevocably commits it to the formation of the membrane-inserted giant ?-barrel pore. This interaction supplies the free energy to overcome the energy barrier (determined here to be ? 19 kcal/mol) to the prepore-to-pore transition by the coordinated disruption of a critical interface within each monomer. These studies provide the first insight to our knowledge into the molecular mechanism that controls the prepore-to-pore transition for a ?PFT. PMID:25646411

Wade, Kristin R; Hotze, Eileen M; Kuiper, Michael J; Morton, Craig J; Parker, Michael W; Tweten, Rodney K

2015-02-17

65

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

OpenAIRE

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

66

Intermolecular potential energy surface and thermophysical properties of ethylene oxide.  

Science.gov (United States)

A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C2H4O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide. PMID:25362314

Crusius, Johann-Philipp; Hellmann, Robert; Hassel, Egon; Bich, Eckard

2014-10-28

67

Intermolecular potential energy surface and thermophysical properties of ethylene oxide  

Energy Technology Data Exchange (ETDEWEB)

A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C{sub 2}H{sub 4}O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide.

Crusius, Johann-Philipp, E-mail: johann-philipp.crusius@uni-rostock.de; Hassel, Egon [Lehrstuhl für Technische Thermodynamik, Universität Rostock, 18059 Rostock (Germany); Hellmann, Robert; Bich, Eckard [Institut für Chemie, Universität Rostock, 18059 Rostock (Germany)

2014-10-28

68

Intermolecular potential energy surface and thermophysical properties of ethylene oxide  

International Nuclear Information System (INIS)

A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C2H4O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide

69

Intermolecular Tl···H-C anagostic interactions in luminescent pyridyl functionalized thallium(I) dithiocarbamates.  

Science.gov (United States)

Crystal structures of novel pyridyl functionalised [Tl(L)]? (L = (N-benzyl-N-methylpyridyl) dithiocarbamate(L1) 1, bis(N-methylpyridyl) dithiocarbamate(L2) 2, (N-methyl(1,4-benzodioxane-6-yl)-N-methylpyridyl)dithiocarbamate(L3) 3, (N-ferrocenyl-N-methylpyridyl) dithiocarbamate(L4) 4) complexes revealed rare intermolecular C-H···Tl anagostic and C-S···Tl interactions forming a six-membered chelate ring about the metal center, which have been assessed by DFT calculations. The strong thallophilic bonding is responsible for the strong luminescent characteristics of the complexes in the solid phase. PMID:25461980

Kumar, Vinod; Singh, Vikram; Gupta, Ajit N; Drew, Michael G B; Singh, Nanhai

2015-01-28

70

Practical aspects of wavelength ratiometry in the studies of intermolecular interactions  

Science.gov (United States)

Wavelength ratiometry (often abbreviated as ?-ratiometry) is one of the most popular methods to study intermolecular interactions that allows obtaining both thermodynamic and kinetic parameters and can be applied in a variety of sensing and imaging technologies. In comparison with simple recording of intensity it allows avoiding many technical problems and realizing many new possibilities. Here we briefly analyze different approaches in ?-ratiometric sensing that use single, double and multiple fluorescence emitters that are based on different mechanisms producing spectroscopic change and concentrate on their practical aspects. Finally we present several examples of successful application of this method and discuss the prospects for its further development.

Demchenko, Alexander P.

2014-12-01

71

The case of infrared carbonyl stretching intensities of 2-bromocyclohexanone: Conformational and intermolecular interaction insights  

Science.gov (United States)

The infrared spectrum of 2-bromocyclohexanone in the vapor phase was obtained for the first time, and the ?Cdbnd O intensity for the more polar equatorial conformer was surprisingly found to be higher than for the axial form, suggesting its larger population, opposite to calculations. Theoretical data for dimeric models showed that attractive intermolecular interactions in the equatorial- equatorial dimer are dominant, but this is not enough to explain the spectroscopic behavior, since the axial- axial dimer remains more stable. The higher C dbnd O molar absorptivity in the equatorial form is therefore invoked to explain its more intense C dbnd O band, as confirmed by charge calculations.

Coelho, Jakelyne V.; Freitas, Matheus P.; Ramalho, Teodorico C.; Martins, Carina R.; Bitencourt, Michelle; Cormanich, Rodrigo A.; Tormena, Cláudio F.; Rittner, Roberto

2010-07-01

72

Photo-induced spin transition of Iron(III) compounds with pi-pi intermolecular interactions.  

Science.gov (United States)

Iron(III) spin-crossover compounds [Fe(pap)(2)]ClO(4) (1), [Fe(pap)(2)]BF(4) (2), [Fe(pap)(2)]PF(6) (3), [Fe(qsal)(2)]NCS (4), and [Fe(qsal)(2)]NCSe (5) (Hpap=2-(2-pyridylmethyleneamino)phenol and Hqsal=2-[(8-quinolinylimino)methyl]phenol) were prepared and their spin-transition properties investigated by magnetic susceptibility and Mössbauer spectroscopy measurements. The iron(III) compounds exhibited spin transition with thermal hysteresis. Single crystals of the iron(III) compounds were obtained as suitable solvent adducts for X-ray analysis, and structures in high-spin (HS) and low-spin (LS) states were revealed. Light-induced excited-spin-state trapping (LIESST) effects of the iron(III) compounds were induced by light irradiation at 532 nm for 1-3 and at 800 nm for 4 and 5. The activation energy E(a) and the low-temperature tunneling rate k(HL)(T-->0) of iron(III) LIESST compound 1 were estimated to be 1079 cm(-1) and 2.4x10(-8) s(-1), respectively, by HS-->LS relaxation experiments. The Huang-Rhys factor S of 1 was also estimated to be 50, which was similar to that expected for iron(II) complexes. It is thought that the slow relaxation in iron(III) systems is achieved by the large structural distortion between HS and LS states. Introduction of strong intermolecular interactions, such as pi-pi stacking, can also play an important role in the relaxation behavior, because it can enhance the structural distortion of the LIESST complex. PMID:19191246

Hayami, Shinya; Hiki, Kenji; Kawahara, Takayoshi; Maeda, Yonezo; Urakami, Daisuke; Inoue, Katsuya; Ohama, Mitsuo; Kawata, Satoshi; Sato, Osamu

2009-01-01

73

Intermolecular interactions of trifluorohalomethanes with Lewis bases in the gas phase: An ab initio study  

Science.gov (United States)

We perform an ab initio computational study of molecular complexes with the general formula CF3X—B that involve one trifluorohalomethane CF3X (X = Cl or Br) and one of a series of Lewis bases B in the gas phase. The Lewis bases are so chosen that they provide a range of electron-donating abilities for comparison. Based on the characteristics of their electron pairs, we consider the Lewis bases with a single n-pair (NH3 and PH3), two n-pairs (H2O and H2S), two n-pairs with an unsaturated bond (H2CO and H2CS), and a single ?-pair (C2H4) and two ?-pairs (C2H2). The aim is to systematically investigate the influence of the electron pair characteristics and the central atom substitution effects on the geometries and energetics of the formed complexes. The counterpoise-corrected supermolecule MP2 and coupled-cluster single double with perturbative triple [CCSD(T)] levels of theory have been employed, together with a series of basis sets up to aug-cc-pVTZ. The angular and radial configurations, the binding energies, and the electrostatic potentials of the stable complexes have been compared and discussed as the Lewis base varies. For those complexes where halogen bonding plays a significant role, the calculated geometries and energetics are consistent with the ?-hole model. Upon formation of stable complexes, the C-X bond lengths shorten, while the C-X vibrational frequencies increase, thus rendering blueshifting halogen bonds. The central atom substitution usually enlarges the intermolecular bond distances while it reduces the net charge transfers, thus weakening the bond strengths. The analysis based on the ?-hole model is grossly reliable but requires suitable modifications incorporating the central atom substitution effects, in particular, when interaction components other than electrostatic contributions are involved.

Wang, Yi-Siang; Yin, Chih-Chien; Chao, Sheng D.

2014-10-01

74

Structural study of citrate layers on gold nanoparticles: role of intermolecular interactions in stabilizing nanoparticles.  

Science.gov (United States)

The structure of citrate adlayers on gold nanoparticles (AuNPs) was investigated. Infrared (IR) and X-ray photoelectron spectroscopy (XPS) analyses indicate citrate anions are adsorbed on AuNPs through central carboxylate groups. A unique structure of adsorbed citrate is determined, and a pH-induced structural transition is presented. IR analysis probes dangling dihydrogen anions (H2Citrate(-)) and hydrogen bonding of carboxylic acid groups between adsorbed and dangling citrate anions. A contribution of steric repulsion between citrate layers to particle stability is characterized. Structure-based modeling, which is consistent with scanning tunneling microscopy (STM) and transmission electron microscopy (TEM) images in the literature, suggests organization details relating to the formation of self-assembled layers on (111), (110), and (100) surfaces of AuNPs. Adsorption characteristics of the citrate layer include the interaction between hydrogen-bonded citrate chains, bilayer formation, surface coverage, and chirality. The enthalpic gain from intermolecular interactions and the importance of molecular structure/symmetry on the adsorption are discussed. Combining the enthalpic factor with surface diffusion and adsorption geometry of (1,2)-dicarboxyl fragments on Au(111), H2Citrate(-) anions effectively stabilize the (111) surface of the AuNPs. The detailed understanding of intermolecular interactions in the molecular adlayer provides insight for nanoparticle formation and stabilization. We expect these findings will be relevant for other nanoparticles stabilized by hydroxy carboxylate-based amino acids and have broad implications in NP-based interfacial studies and applications. PMID:24422457

Park, Jong-Won; Shumaker-Parry, Jennifer S

2014-02-01

75

[(PPh(3))Ag(HCB(11)Me(11))]: a complex with intermolecular Ag.H3C interactions.  

OpenAIRE

Both in the solid state and in solution, the complex, [(PPh3)Ag(HCB11Me11)] displays significant intermolecular Ag ? H3C interactions. This complex serves as a model for the interaction between a d10 metal center and an alkane.

Ingleson, Mj; Mahon, Mf; Patmore, Nj; Ruggiero, Gd; Weller, As

2002-01-01

76

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)

77

Theoretical study of intermolecular interactions in nanoporous networks on boron doped silicon surface  

Science.gov (United States)

Supramolecular networks on a doped boron silicon surface under ultra high vacuum (UHV) have been recently obtained (Makoudi et al., 2013). The used molecule contains different end-groups, bearing either bromine, iodine or hydrogen atoms denoted 1,3,5-tri(4?-bromophenyl)benzene (TBB), 1,3,5-tri(4-iodophenyl)benzene (TIB) and 1,3,5-triphenyl-benzene (THB). To explain the formation of the nanoporous structures, interactions of the type aryl-X⋯H hydrogen bonds (X being a halogen atom) have been proposed. In order to obtain a complete insight of the stabilizing interaction in these networks adsorbed on the Si(1 1 1)?3x?3R30°-boron surface, we present a full density-functional-theory study taking the van der Waals interactions into account. We investigated the energetic and structural properties of three different nanoporous networks constituted by TBB, TIB and THB molecules. The electronic studies allow us to identify hydrogen bond and dipole-dipole intermolecular interactions in the supramolecular halogen networks, whereas only dipole-dipole interactions are present in the 1,3,5-triphenyl-benzene nanoporous network.

Boukari, Khaoula; Duverger, Eric; Hanf, Marie-Christine; Stephan, Régis; Sonnet, Philippe

2014-11-01

78

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

International Nuclear Information System (INIS)

Highlights: • Ultrasonic, volumetric and spectroscopic properties of 2-CletOH + DMAE/DEAE liquid mixtures were studied. • Results showed the presence of intermolecular hydrogen bonding between the unlike molecules. • H-bonding occurred between hydrogen atom of –OH group of 2-CletOH and oxygen atom of –OH group of DMAE/DEAE. • The strength of intermolecular interactions was found in order: 2-CletOH + DEAE > 2-CletOH + DMAE. - Abstract: 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

79

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: • Ultrasonic, volumetric and spectroscopic properties of 2-CletOH + DMAE/DEAE liquid mixtures were studied. • Results showed the presence of intermolecular hydrogen bonding between the unlike molecules. • H-bonding occurred between hydrogen atom of –OH group of 2-CletOH and oxygen atom of –OH group of DMAE/DEAE. • The strength of intermolecular interactions was found in order: 2-CletOH + DEAE > 2-CletOH + DMAE. - Abstract: 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 (?{sub S}), intermolecular free length (L{sub f}), molar sound velocity (R), molar compressibility (B) and specific acoustic impedance (Z) along with excess values of ultrasonic velocity (u{sup E}), adiabatic compressibility (?{sub S}{sup E}), intermolecular free length (L{sub f}{sup E}), acoustic impedance (Z{sup E}) and molar volume (V{sub m}{sup E}). 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 [Material Science Research Laboratory, Department of Physics, University of Lucknow, Lucknow 226 007 (India); Awasthi, Anjali [Department of Physics, BBD University, Lucknow 227 015 (India); Awasthi, Aashees, E-mail: aasheesawasthi@rediffmail.com [Material Science Research Laboratory, Department of Physics, University of Lucknow, Lucknow 226 007 (India)

2013-09-23

80

Intermolecular nonradiative energy transfer in clusters with plasmonic nanoparticles  

Science.gov (United States)

The influence of carbon (fullerenes, nanotubes) and metal (Ni, Co, Cu, Ag) nanoparticles on the nonradiative electronic excitation energy transfer between the molecules of organic dyes (acrylic orange as a donor and Nile blue as an acceptor) in alcohol solutions of polyvinylbutyral is studied. It is found that, at particular concentrations of the mixture components, plasmonic nanoparticles affect the nonradiative electronic excitation energy transfer, which is manifested in an increase in the intensity of sensitized fluorescence of acceptors with simultaneous quenching of the fluorescence of donors. A very simple model is proposed to illustrate the observed redistribution of luminescence intensity between the spectral bands of the general spectrum. Molecular-dynamic calculations of the structure of nanocomposites performed for the same purpose confirmed the formation of associated molecular plasmonic complexes fixed by macrochain links.

Kucherenko, M. G.; Stepanov, V. N.; Kruchinin, N. Yu.

2015-01-01

81

Effects of Weak Intermolecular Interactions on the Molecular Isomerism of Tricobalt Metal Chains  

Energy Technology Data Exchange (ETDEWEB)

Depending on the number of interstitial solvent molecules, n, crystals of the linear chain compound Co3(dipyridylamide)4Cl2{center_dot}nCH2Cl2 adopt either symmetrical or unsymmetrical metal chain structures. We explore here the possible reasons for such behavior using Hirshfeld surface analysis of intermolecular interactions as well as the charge density determined from 100(1) K X-ray diffraction data on the unsymmetrical complex Co3(dipyridylamide)4Cl2{center_dot}2.11CH2Cl2, u-1, and crystal structures of u-1 determined from single crystal synchrotron X-ray diffraction data at 20, 150, and 300 K. The new crystal structures are compared with previous structural results on a crystal with slightly different solvent content. This change in solvent content only affects the bond distances to atom Co(3), which are also strongly affected by temperature changes due to a spin crossover transition. Large differences in intermolecular interactions are revealed by the Hirshfeld surface analysis between symmetrical (s-1) and unsymmetrical (u-1) crystal solvates, suggesting that the molecular isomerism is strongly influenced by crystal packing effects. Topological analysis of the static electron density of u-1 suggests that there is direct metal-metal bonding for both the shorter Co(1)-Co(2) and the longer Co(2)-Co(3) contact. The approximate description of the system as a (Co2)2+-dimer and an isolated Co2+-ion is reflected in the character of the metal-ligand interactions, which are more ionic for the isolated Co(3) atom, and the topological charges Co(1)+0.50, Co(2)+0.77, and Co(3)+1.36. The two termini of u-1 are found to be very different, both in terms of structural surroundings as well as topology. The central Co(2) atom is similar to a cobalt atom in a tetragonally distorted octahedral environment resulting in preferred occupancy in the t2g orbitals. The Co(1) atom has significant deformation in the xz and yz planes (z along the chain axis, x and y toward ligands) reflecting covalent interactions with the terminal chlorine atom Cl(1). The Co(3) atom has a relatively high occupancy of the dx2-y2 orbital and a relatively low occupancy of the dxy orbital confirming that these orbitals are involved in the spin crossover process and predominantly responsible for the observed variation in bond lengths with temperature.

Poulsen, R.; Overgaard, J; Schulman, A; Østergaard, C; Murillo, C; Spackman, M; Iversen, B

2009-01-01

82

Effects of weak intermolecular interactions on the molecular isomerism of tricobalt metal chains.  

Science.gov (United States)

Depending on the number of interstitial solvent molecules, n, crystals of the linear chain compound Co(3)(dipyridylamide)(4)Cl(2) x nCH(2)Cl(2) adopt either symmetrical or unsymmetrical metal chain structures. We explore here the possible reasons for such behavior using Hirshfeld surface analysis of intermolecular interactions as well as the charge density determined from 100(1) K X-ray diffraction data on the unsymmetrical complex Co(3)(dipyridylamide)(4)Cl(2) x 2.11 CH(2)Cl(2), u-1, and crystal structures of u-1 determined from single crystal synchrotron X-ray diffraction data at 20, 150, and 300 K. The new crystal structures are compared with previous structural results on a crystal with slightly different solvent content. This change in solvent content only affects the bond distances to atom Co(3), which are also strongly affected by temperature changes due to a spin crossover transition. Large differences in intermolecular interactions are revealed by the Hirshfeld surface analysis between symmetrical (s-1) and unsymmetrical (u-1) crystal solvates, suggesting that the molecular isomerism is strongly influenced by crystal packing effects. Topological analysis of the static electron density of u-1 suggests that there is direct metal-metal bonding for both the shorter Co(1)-Co(2) and the longer Co(2)-Co(3) contact. The approximate description of the system as a (Co(2))(2+)-dimer and an isolated Co(2+)-ion is reflected in the character of the metal-ligand interactions, which are more ionic for the isolated Co(3) atom, and the topological charges Co(1)(+0.50), Co(2)(+0.77), and Co(3)(+1.36). The two termini of u-1 are found to be very different, both in terms of structural surroundings as well as topology. The central Co(2) atom is similar to a cobalt atom in a tetragonally distorted octahedral environment resulting in preferred occupancy in the t(2g) orbitals. The Co(1) atom has significant deformation in the xz and yz planes (z along the chain axis, x and y toward ligands) reflecting covalent interactions with the terminal chlorine atom Cl(1). The Co(3) atom has a relatively high occupancy of the d(x(2)-y(2)) orbital and a relatively low occupancy of the d(xy) orbital confirming that these orbitals are involved in the spin crossover process and predominantly responsible for the observed variation in bond lengths with temperature. PMID:19438202

Poulsen, Rasmus D; Overgaard, Jacob; Schulman, Alexander; Østergaard, Christina; Murillo, Carlos A; Spackman, Mark A; Iversen, Bo B

2009-06-10

83

Study of the Crystal Structure of Titanylphthalocyanine by Rietveld Analysis and Intermolecular Energy Minimization Method  

Science.gov (United States)

Rietveld analysis and intermolecular energy minimization were used to refine the crystal structure parameters of one of the polymorphs of titanylphthalocyanine (TiOPc), which is a highly photosensitive pigment used in electrophotography. The most probable crystal structure is proposed to be a monoclinic unit cell, space group P21/c. The unit cell parameters are a{=}1.385 nm, b{=}1.392 nm, c{=}1.514 nm and ?{=}120.22°. There are four molecules per unit cell.

Oka, Kozo; Okada, Okimasa; Nukada, Katumi

1992-07-01

84

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

85

Intermolecular interactions and substrate effects for an adamantane monolayer on a Au(111) surface  

Science.gov (United States)

We study theoretically and experimentally the infrared (IR) spectrum of an adamantane monolayer on a Au(111) surface. Using a STM-based IR spectroscopy technique (IRSTM) we are able to measure both the nanoscale structure of an adamantane monolayer on Au(111) as well as its infrared spectrum, while DFT-based ab initio calculations allow us to interpret the microscopic vibrational dynamics revealed by our measurements. We find that the IR spectrum of an adamantane monolayer on Au(111) is substantially modified with respect to the gas-phase IR spectrum. The first modification is caused by the adamantane-adamantane interaction due to monolayer packing, and it reduces the IR intensity of the 2912 cm-1 peak (gas phase) by a factor of 3.5. The second modification originates from the adamantane-gold interaction, and it increases the IR intensity of the 2938 cm-1 peak (gas phase) by a factor of 2.6 and reduces its frequency by 276 cm-1. We expect that the techniques described here can be used for an independent estimate of substrate effects and intermolecular interactions in other diamondoid molecules and for other metallic substrates.

Sakai, Yuki; Nguyen, Giang D.; Capaz, Rodrigo B.; Coh, Sinisa; Pechenezhskiy, Ivan V.; Hong, Xiaoping; Wang, Feng; Crommie, Michael F.; Saito, Susumu; Louie, Steven G.; Cohen, Marvin L.

2013-12-01

86

Modeling intermolecular interactions of physisorbed organic molecules using pair potential calculations  

International Nuclear Information System (INIS)

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.

87

Intermolecular interactions in ternary solutions of some 1,2,4-triazolium ylids studied by spectral means  

Science.gov (United States)

Triazolium ylids are dipolar molecules with separated charges in their ground electronic state; the positive charge is located on one Nitrogen atom belonging to the heterocycle and the negative charge is located near the ylid carbanion. The intramolecular charge transfer from the carbanion to heterocycle gives a visible electronic absorption band, very sensitive to the solvent nature. Its position in the wavenumber scale offers information about the intermolecular interactions in which the ylid molecules are engaged. The spectral study revealed the presence of both universal and specific interactions in solutions of 1,2,4-triazolium ylids with protic solvents. By choosing adequate binary solvents, the contribution of the specific interaction of the weak hydrogen bond between the -OH atomic group of the protic solvents and the ylid carbanion can be estimated. Ternary solutions of the studied ylids achieved with Methanol +Benzene, Water + Ethanol and 1,3 Propanediol + Dimethyl formamide binary solvents are analyzed from spectral point of view and the difference between the potential energies in molecular pairs of the types: 1,2,4-triazolium ylid-protic solvent and 1,2,4-triazolium ylid-non protic were estimated on the basis of the statistic cell model of ternary solutions.

Closca, Valentina; Melniciuc-Puica, Nicoleta; Dorohoi, Dana Ortansa; Benchea, A. C.

2014-08-01

88

Anti-plasticizing effect of amorphous indomethacin induced by specific intermolecular interactions with PVA copolymer.  

Science.gov (United States)

The mechanism of how poly(vinyl alcohol-co-acrylic acid-co-methyl methacrylate) (PVA copolymer) stabilizes an amorphous drug was investigated. Solid dispersions of PVA copolymer, poly(vinyl pyrrolidone) (PVP), and poly(vinyl pyrrolidone-co-vinyl acetate) (PVPVA) with indomethacin (IMC) were prepared. The glass transition temperature (Tg)-proportion profiles were evaluated by differential scanning calorimetry (DSC). General Tg profiles decreasing with the IMC ratio were observed for IMC-PVP and IMC-PVPVA samples. An interesting antiplasticizing effect of IMC on PVA copolymer was observed; Tg increased up to 20% IMC ratio. Further addition of IMC caused moderate reduction with positive deviation from theoretical values. Specific hydrophilic and hydrophobic interactions between IMC and PVA copolymer were revealed by infrared spectra. The indole amide of IMC played an important role in hydrogen bonding with PVA copolymer, but not with PVP and PVPVA. X-ray diffraction findings and the endotherm on DSC profiles suggested that PVA copolymer could form a semicrystalline structure and a possibility of correlation of the crystallographic nature with its low hygroscopicity was suggested. PVA copolymer was able to prevent crystallization of amorphous IMC through both low hygroscopicity and the formation of a specific intermolecular interaction compared with that with PVP and PVPVA. PMID:24890320

Ueda, Hiroshi; Aikawa, Shohei; Kashima, Yousuke; Kikuchi, Junko; Ida, Yasuo; Tanino, Tadatsugu; Kadota, Kazunori; Tozuka, Yuichi

2014-09-01

89

Sensitivity of predicted gas hydrate occupancies on treatment of intermolecular interactions.  

Science.gov (United States)

The sensitivity of gas hydrate occupancies predicted on the basis of van der Waals-Platteeuw theory is investigated, as a function of the intermolecular guest-water interaction potential model, and of the number of water molecules taken into account. Simple analytical correction terms that account for the interactions with the water molecules beyond the cutoff distance are introduced, and shown to improve significantly the convergence rate, and hence the efficiency of the computation of the Langmuir constants. The predicted cage occupancies in pure methane and pure carbon dioxide clathrates, calculated using different recent guest-water pair potentials models derived from ab initio calculations, can vary significantly depending on the model. That sensitivity becomes especially strong in the case of multiple guest clathrates. It is shown that the abundances of coenclathrated molecules in multiple guest clathrate hydrates potentially formed on the surface of Mars can vary by more than two orders of magnitude depending on the model. These results underline the strong need for experimental data on pure and multiple guest clathrate hydrates, in particular in the temperature and pressure range that are relevant in extreme environment conditions, to discriminate among the theoretical models. PMID:20232974

Thomas, Caroline; Picaud, Sylvain; Ballenegger, Vincent; Mousis, Olivier

2010-03-14

90

Mass analyzed threshold ionization of phenol?CO: Intermolecular binding energies of a hydrogen-bonded complex  

Science.gov (United States)

[Phenol?CO]+ was studied using a combination of two-color resonant zero kinetic energy (ZEKE) spectroscopy and mass analyzed threshold ionization (MATI) spectroscopy to investigate the interaction of the CO ligand with a hydrogen-bonding cation. Vibrational progressions were observed in three intermolecular modes, the in-plane bend (42 cm-1), stretch (130 cm-1), and in-plane wag (160 cm-1), and are consistent with a planar hydrogen-bonded structure where the CO bonds through the carbon atom to the phenol OH group. Dissociation energies for the S0, S1, and D0 states were determined as 659±20, 849±20, and 2425±10 cm-1, respectively. The cationic and neutral dissociation energies of the phenol?CO complex are considerably stronger than those of phenol?N2, demonstrating the extent to which the larger quadrupole of CO affects the strength of binding.

Haines, Stephen R.; Dessent, Caroline E. H.; Müller-Dethlefs, Klaus

1999-08-01

91

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

92

Intermolecular vs molecule–substrate interactions: A combined STM and theoretical study of supramolecular phases on graphene/Ru(0001  

Directory of Open Access Journals (Sweden)

Full Text Available The competition between intermolecular interactions and long-range lateral variations in the substrate–adsorbate interaction was studied by scanning tunnelling microscopy (STM and force field based calculations, by comparing the phase formation of (sub- monolayers of the organic molecules (i 2-phenyl-4,6-bis(6-(pyridin-3-yl-4-(pyridin-3-ylpyridin-2-ylpyrimidine (3,3'-BTP and (ii 3,4,9,10-perylene tetracarboxylic-dianhydride (PTCDA on graphene/Ru(0001. For PTCDA adsorption, a 2D adlayer phase was formed, which extended over large areas, while for 3,3'-BTP adsorption linear or ring like structures were formed, which exclusively populated the areas between the maxima of the moiré structure of the buckled graphene layer. The consequences for the competing intermolecular interactions and corrugation in the adsorption potential are discussed and compared with the theoretical results.

Michael Roos

2011-07-01

93

Intermolecular Attractions  

Science.gov (United States)

Intermolecular attractions are responsible for everything from the temperatures at which substances boil to the power of your immune system in recognizing pathogens and the climbing ability of geckos! Feel the strength of London dispersion and dipole-dipole attractions, explore how intermolecular attractions affect boiling point and solubility, and investigate the special role of hydrogen bonds in DNA. Finally, design your own antibody based on intermolecular attractions.

The Concord Consortium

2011-12-11

94

Theory of intermolecular forces  

CERN Document Server

Theory of Intermolecular Forces deals with the exposition of the principles and techniques of the theory of intermolecular forces. The text focuses on the basic theory and surveys other aspects, with particular attention to relevant experiments. The initial chapters introduce the reader to the history of intermolecular forces. Succeeding chapters present topics on short, intermediate, and long range atomic interactions; properties of Coulomb interactions; shape-dependent forces between molecules; and physical adsorption. The book will be of good use to experts and students of quantum mechanics

Margenau, H; Ter Haar, D

1971-01-01

95

Intermolecular Interactions in Ternary Glycerol–Sample–H2O : Towards Understanding the Hofmeister Series (V)  

DEFF Research Database (Denmark)

We studied the intermolecular interactions in ternary glycerol (Gly)–sample (S)–H2O systems at 25?°C. By measuring the excess partial molar enthalpy of Gly, HGlyEHEGly, we evaluated the Gly–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 1P–S–H2O in that Na+, F? and Cl? are found as hydration centers from the induced changes on HIP-IPEHEIP--IP in the presence of S, while Br?, I?, and SCN? 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 Hofmeister’s concept of “H2O withdrawing power.” Br?, I? and SCN?, 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

96

Investigations on stabilities and intermolecular interactions of different naphthalene derivatives dimers by using B3LYP and M06-2X density functional calculations  

Science.gov (United States)

In this paper, the stabilities and hydrogen bond interactions of 4-chloro-1-naphthol, 1-hydrox-ynaphthalene and 1,4-dihydroxynaphthalene dimers have been theoretically investigated by means of study on binding energies with nonlocal hybrid three-parameter Lee-Yang-Parr, B3LYP, and M06-class functional calculations. Calculations on dimers aim to provide as a test of the efficacy of M06 calculations for intermolecular interaction calculations and more strongly bound systems. For hydroxyl- and halo-substituted derivatives of naphthalene, total electronic energies, their correction for the zero point vibrational energies with some calculated thermodynamic properties and their relative differences are together in order to discuss the rotamer structures. Static (hyper) polarizabilities and the electric dipole moments, frontier molecular orbital energy gaps and the relationships between them have been interpreted. Generally, they are seen that the calculated geometric parameters and spectral results were in a good agreement with the corresponding experimental data.

Karakaya, M.; Çiçek, A.; Ucun, F.; Yildiz, M.

2014-12-01

97

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. PMID:24907987

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

2014-06-01

98

THE INTERACTION OF PARAMAGNETIC RELAXATION REAGENTS WITH INTRA- AND INTERMOLECULAR HYDROGEN BONDED PHENOLS  

Science.gov (United States)

Intermolecular electron-nuclear 13-C relaxation times (T(1)sup e's) from solutions containing the paramagnetic relaxation reagent (PARR), Cr(acac)3, used in conjunction with 13-C T(1)'s in diamagnetic solutions (intramolecular 13-C - (1)H dipolar T(1)'s) provide a significant inc...

99

On the manifestation of Casimir effects in intermolecular interactions via the method of induced moments  

International Nuclear Information System (INIS)

A versatile, alternative method for calculating long-range interactions between atomic and molecular systems within the framework of non-relativistic quantum electrodynamics is the induced multipole moment approach. In the present contribution it is employed to compute the dispersion energy shift between a pair of neutral polarizable molecules in either ground or excited electronic states, and the change in mutual interaction energy caused by the action of an intense external radiation field. In this method the moments induced at each centre are coupled to each other via the resonant electric dipole-electric dipole interaction tensor, giving rise to an energy shift. On evaluating the expectation values for states corresponding to (i) both molecules in the ground state and the field in the vacuum state, (ii) both species excited and the field containing no photons, and (iii) both molecules in the ground state with the field containing I photons, respectively result in energy shifts for each of the three processes described above. For the modification of the dispersion interaction by laser light, two distinct mechanisms are identified. One, the dynamic contribution, is proportional to the polarizability of each molecule, and a second, the static term, involves the product of the static moment at one centre and the molecular first hyperpolarizability of the other entity. In both cases the energy shift has a linear dependence on radiation field intensity. After molecular adiation field intensity. After molecular averaging, the static contribution is found to vanish.

100

Intermolecular interaction in density functional theory: Application to carbon nanotubes and fullerenes  

Science.gov (United States)

A theoretical study of weak interactions in graphitic materials such as carbon nanotubes (CNTs), fullerenes, and graphene is presented here. Based on a localized orbital density-functional theory formalism, our treatment which has already been applied for graphene-graphene interaction describes independently the weak chemical as well as the van der Waals interactions with high accuracy. The weak chemical interaction is described in the frame of the linear combination of atomic orbital S2 model based on a weak overlap expansion, and the van der Waals interaction is treated in the dipolar approximation, taking into account virtual transitions of high energy. This formalism is applied here to the case of lateral interaction between CNTs, C60 dimers, adsorption of C60 on graphene and CNT, and encapsulation of C60 and CNT. The power law of the interaction is analyzed, and useful parameters such as C6 coefficients and an exponential model for the “chemical” interaction are extracted. Beyond the study of graphitic materials, this work opens interesting perspectives in the analysis of weakly bonded metal/organics interfaces.

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

2009-04-01

101

Intermolecular interactions involving noble-gas hydrides: Where the blue shift of vibrational frequency is a normal effect  

Science.gov (United States)

The intermolecular interactions of noble-gas hydride molecules (HNgY) are overviewed with emphasis on the experimentally observed species. These interactions include molecular complexes, interaction with surrounding matrix (matrix-site effect), and librational motion in a solid matrix. The developed models qualitatively explain all experimental IR spectral features of the matrix-isolated HNgY molecules. A number of complexes between noble-gas hydrides and other molecules have been experimentally and computationally studied. These complexes often involve hydrogen bonds and they show unusual spectral effects, such as large blue shifts of the H-Ng stretching frequencies. The blue shift seems to be the normal effect for the complexes of HNgY molecules. Remarkably, the complexes without hydrogen bonding also show substantial vibrational blue shifts. The H-Ng stretching blue shift presumably originates from the enhanced (HNg) +Y - charge separation upon complex formation. It is possible that the solvation and intermolecular interaction of the HNgY molecules can stabilize them in condense phases at normal (not cryogenic) conditions. Preparation of helium and neon compounds can be also discussed in terms of complexation (solvation) induced stabilization. In particular, the complexation-induced stabilization of hypothetical HHeF is computationally studied.

Lignell, Antti; Khriachtchev, Leonid

2008-10-01

102

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

103

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.

104

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 between 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

2012-01-01

105

Identification of molecular crystals capable of undergoing an acyl-transfer reaction based on intermolecular interactions in the crystal lattice.  

Science.gov (United States)

Investigation of the intermolecular acyl-transfer reactivity in molecular crystals of myo-inositol orthoester derivatives and its correlation with crystal structures enabled us to identify the essential parameters to support efficient acyl-transfer reactions in crystals: 1)?the favorable geometry of the nucleophile (-OH) and the electrophile (C-O) and 2)?the molecular assembly, reinforced by C-H???? interactions, which supports a domino-type reaction in crystals. These parameters were used to identify another reactive crystal through a data-mining study of the Cambridge Structural Database. A 2:1 co-crystal of 2,3-naphthalene diol and its di-p-methylbenzoate was selected as a potentially reactive crystal and its reactivity was tested by heating the co-crystals in the presence of solid sodium carbonate. A facile intermolecular p-toluoyl group transfer was observed as predicted. The successful identification of reactive crystals opens up a new method for the detection of molecular crystals capable of exhibiting acyl-transfer reactivity. PMID:23934729

Tamboli, Majid I; Krishnaswamy, Shobhana; Gonnade, Rajesh G; Shashidhar, Mysore S

2013-09-16

106

Tuning intermolecular interactions to enhance solid-state nanopore force spectroscopy  

Science.gov (United States)

Nanopores, nanometer sized holes in membranes, have recently come into prominence as tools for single molecule sensing. A technique called nanopore force spectroscopy uses the nanopore to probe energy landscapes between molecules. With the development of this technique, it will be possible for molecular recognition in complex fluids, such as blood. However, before that can be possible, solid-state nanopores, commonly fabricated in silicon nitride membranes, and having very confined sizes and charged surfaces, need to be optimized to minimize unwanted interactions between solution-phase molecules and the surface. DNA, for example, a crucial part of nanopore force spectroscopy, frequently sticks to the nanopore surface. Surface functionalization techniques, both on the nanopore and molecular surface, were attempted in this thesis work. These surface functionalization methods aimed to reduce surface charge or alter molecular properties in order to minimize the unwanted surface interactions, and they include silane modification, fluid lipid bilayer coating, and surfactant self-assembly on the DNA phosphate backbone. Results from some of these methods yield insights to improve nanopore force spectroscopy performance that will minimize the unwanted surface interactions and deliver on the promise of nanopore sensing.

Foun, Elaine

107

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

108

Features of polymer chain dynamics as revealed by intermolecular nuclear magnetic dipole-dipole interaction: model calculations and field-cycling NMR relaxometry.  

Science.gov (United States)

Proton NMR phenomena such as spin-lattice relaxation, free-induction decays, and solid echoes are analyzed with respect to contributions by intermolecular dipole-dipole interactions in polymer melts. The intermolecular dipole-dipole correlation function is calculated by taking into account the correlation hole effect characteristic for polymer melts. It is shown that the ratio between the intra- and intermolecular contributions to NMR measurands depends on the degree of isotropy of chain dynamics anticipated in different models. This, in particular, refers to the tube/reptation model that is intrinsically anisotropic in clear contrast to n-renormalized Rouse models, where no such restriction is implied. Due to anisotropy, the tube/reptation model predicts that the intramolecular contribution to the dipole-dipole correlation function increases with time relative to the intermolecular contribution. Therefore, the intramolecular contribution is expected to dominate NMR measurands by tendency at long times (or low frequencies). On the other hand, the isotropic nature of the n-renormalized Rouse model suggests that the intermolecular contribution tends to prevail on long-time scales (or low frequencies). Actually, theoretical estimations and the analysis of experimental spin-lattice relaxation data indicate that the intermolecular contribution to proton NMR measurands is no longer negligible for times longer than 10(-7) s-10(-6) s corresponding to frequencies below the megahertz regime. Interpretations not taking this fact into account need to be reconsidered. The systematic investigation of intermolecular interactions in long-time/low frequency proton NMR promises the revelation of the dynamic features of segment displacements relative to each other in polymer melts. PMID:20210412

Fatkullin, N; Gubaidullin, A; Stapf, S

2010-03-01

109

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: • The inelastic neutron spectrum of cyclopentanone was obtained. • The neutron spectrum of the pure compound reveals presence of C–H?O hydrogen bonds. • Almost exact match between simulated C–H?O bonded dimer and experimental spectra. • Anti-translational ?H?O mode assigned to band at 95 cm{sup ?1} and confirmed by DFT results. - Abstract: The inelastic neutron scattering (INS) spectra of cyclopentanone were obtained for pure and 50% CCl{sub 4} 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{sup ?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{sup ?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., E-mail: pmvaz@fc.ul.pt [CQB, Department of Chemistry and Biochemistry, Faculty of Science, University of Lisbon, 1749-016 Lisbon (Portugal); Nolasco, Mariela M. [Departamento de Química – CICECO, Universidade de Aveiro, P-3810-193 Aveiro (Portugal); Ribeiro-Claro, Paulo J.A., E-mail: prc@ua.pt [Departamento de Química – CICECO, Universidade de Aveiro, P-3810-193 Aveiro (Portugal)

2013-12-12

110

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.

2013-08-01

111

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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english 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; Regiane C. M. U. de, Araújo.

2007-08-01

112

Intermolecular spectroscopy of gases  

International Nuclear Information System (INIS)

Spectroscopic techniques have been very successfully applied to the study of individual molecules. The same techniques can also be used to investigate intermolecular interactions. Collision-induced absorption (CIA) and collision-induced light scattering (CILS) are important examples of intermolecular interactions. These effects can be described by the dynamical information contained in the general intermolecular correlation functions. One of the aims of this review is to stress the central role of these correlation functions in the field of intermolecular spectroscopy. Because they have a well-defined physical meaning, they are very suitable for the purpose of introducing new physical approximations, particularly in the case of liquids. Some aspects of the theory of CIA will be discussed, mainly as applied to gases. References to similar situations in CILS will occasionally be made, but no comprehensive review will be attempted. One of the basic quantities in CIA is the absorption coefficient. The question is investigated wether it can be expanded in powers of the density. Finally, the moments of the spectrum, interference effects and line shapes are discussed. (KBE)

113

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

Science.gov (United States)

It is the purpose of this paper to extract unlike intermolecular potential energies of five carbon dioxide-based binary gas mixtures including CO2-He, CO2-Ne, CO2-Ar, CO2-Kr, and CO2-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 K 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.

Moghadasi, Jalil; Yousefi, Fakhri; Papari, Mohammad Mehdi; Faghihi, Mohammad Ali; Mohsenipour, Ali Asghar

2009-09-01

114

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.

2009-10-01

115

Intermolecular electronic interactions in the primary charge separation in bacterial photosynthesis  

Energy Technology Data Exchange (ETDEWEB)

In this paper the intermolecular overlap approximation is used to calculate the relative magnitudes of the electronic transfer integrals between the excited singlet state ({sup 1}P*) of the bacteriochlorophyll dimer (P) and the accessory bacteriochlorophyll (B) and between B{sup {minus}} and bacteriopheopytin (H), along the L and M subunits of the reaction center (RC) of Rps. viridis. The ratio of the electron-transfer integrals for B{sub L}{sup {minus}}H{sub L}{sup {minus}}B{sub L}H{sub L}{minus} and for B{sub M}{sup {minus}}H{sub M}{minus}B{sub M}H{sub M}{sup {minus}} was calculated to be 2.1 {plus minus} 0.5, which together with the value of 2.8 {plus minus} 0.7 for the ratio of the transfer integrals for {sup 1}P*B{sub L}-P{sup +}B{sub L}- and for {sup 1}P*B{sub M}-P{sup +}B{sub M}- results in the electronic contribution of 33 {plus minus} 16 to the ratio k{sub L}/k{sub m} of the rate constants k{sub L} and k{sub M} for the primary charge separation across the L and M branches of the RC, respectively. The asymmetry of the electronic coupling terms, which originates from the combination of the asymmetry in the charge distribution of {sup 1}P* and of structural asymmetry of the P-M and B-H arrangements across the L and M subunits, provides a major contribution to the unidirectionality of the charge separation in bacterial photosynthesis. A significant contribution to the transfer integrals between adjacent pigments originates from nearby methyl groups through hyperconjugation. The ratio 6 {plus minus} 2 of the transfer integrals for {sup 1}P*B{sub L}-P{sup +}B{sub L}- and for B{sub L}-H{sub L}-B{sub L}H{sub L}- was utilized to estimate the energetic parameters required to ensure the dominance of the superexchange mediated unistep electron transfer {sup 1}P*BH {yields} P{sup +}BH{sup {minus}} over the thermally activated {sup 1}P*B {yields} P{sup +}B{sup {minus}} process. 31 refs., 6 figs., 2 tabs.

Plato, M.; Moebius, K.; Michel-Beyerle, M.E.; Bixon, M.; Jortner, J. (Freie Universitaet Berlin (West Germany))

1988-10-26

116

12C/13C 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 12C/13C 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 CHF3. 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

117

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

118

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.

119

Two alternative derivations of the static contribution to the radiation-induced intermolecular energy shift  

International Nuclear Information System (INIS)

Two contrasting physical viewpoints and calculational approaches are adopted within the framework of molecular quantum electrodynamics for the evaluation of the static contribution to the change in mutual interaction energy between a pair of electric dipole polarizable molecules in an intense radiation field. This term arises when a real photon is scattered by the same molecular center with coupling between the two bodies occurring via exchange of a single virtual photon. In one method it is found that utilization of an effective three-photon interaction operator enables the energy shift to be obtained using second order perturbation theory with summation over only four time-ordered diagrams, each of which contain collapsed interaction vertices. The result is then shown to be obtained even more easily in a second approach that involves calculating the expectation values for both molecules in the ground electronic state and the field containing N photons of mode (k-vector,?) of the electric dipole moments induced at each molecule by the incident field, which are coupled to the resonant dipole-dipole interaction tensor. The static contribution in question is shown to arise from the interaction of a permanent electric dipole moment in one species with the first hyperpolarizability of the other. Both methods are compared and contrasted with a previous computation in which contributions to the energy shift arising from 48 time-ordered diagrams were summed using fourth ordred diagrams were summed using fourth order perturbation theory

120

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 connect the molecules into chains propagating in [011], which are cross-linked via C—H...? interactions, generating a three-dimensional network. Aromatic ?–? stacking also occurs [shortest centroid–centroid separation = 3.6012?(11?Å].

Richard Betz

2011-05-01

121

The structural basis of androgen receptor activation: Intramolecular and intermolecular amino–carboxy interactions  

OpenAIRE

Nuclear receptors (NRs) are ligand-regulated transcription factors important in human physiology and disease. In certain NRs, including the androgen receptor (AR), ligand binding to the carboxy-terminal domain (LBD) regulates transcriptional activation functions in the LBD and amino-terminal domain (NTD). The basis for NTD–LBD communication is unknown but may involve NTD–LBD interactions either within a single receptor or between different members of an AR dimer. Here, measurement of FRET...

Schaufele, Fred; Carbonell, Xavier; Guerbadot, Martin; Borngraeber, Sabine; Chapman, Mark S.; Ma, Aye Aye K.; Miner, Jeffrey N.; Diamond, Marc I.

2005-01-01

122

Structural investigations on N'-substituted N-acylguanidines - Intermolecular interactions with solvents, anions and receptors  

OpenAIRE

Acylguanidines are an abundant class of compounds with various applications in organic and pharmaceutical chemistry. Within the subgroup of N’-substituted and especially monoalkylated N-acylguanidines, highly potent and selective ligands for G protein coupled receptors have been identified in recent years. In the field of molecular recognition, acylguanidines are valued for their ability to form strong fork-like hydrogen bond (H-bond) interactions with carboxylate anions. Although their bas...

Kleinmaier, Roland

2011-01-01

123

Macrocyclic ?-Sheet Peptides that Mimic Protein Quaternary Structure through Intermolecular ?-Sheet Interactions  

OpenAIRE

This paper reports the design, synthesis, and characterization of a family of cyclic peptides that mimic protein quaternary structure through ?-sheet interactions. These peptides are 54-membered-ring macrocycles comprising an extended heptapeptide ?-strand, two Hao ?-strand mimics [JACS 2000, 122, 7654] joined by one additional ?-amino acid, and two ?-linked ornithine ?-turn mimics [JACS 2003, 125, 876]. Peptide 3a, as the representative of these cyclic peptides, contains a heptapeptide...

Khakshoor, Omid; Demeler, Borries; Nowick, James S.

2007-01-01

124

Intermolecular interactions in highly concentrated protein solutions upon compression and the role of the solvent  

Science.gov (United States)

The influence of high hydrostatic pressure on the structure and protein-protein interaction potential of highly concentrated lysozyme solutions up to about 370 mg ml-1 was studied and analyzed using small-angle X-ray scattering in combination with a liquid-state theoretical approach. In the concentration region below 200 mg ml-1, the interaction parameters of lysozyme solutions are affected by pressure in a nonlinear way, which is probably due to significant changes in the structural properties of bulk water, i.e., due to a solvent-mediated effect. Conversely, for higher concentrated protein solutions, where hydration layers below ˜4 water molecules are reached, the interaction potential turns rather insensitive to compression. The onset of transient (dynamic) clustering is envisaged in this concentration range. Our results also show that pressure suppresses protein nucleation, aggregation and finally crystallization in supersaturated condensed protein solutions. These findings are of importance for controlling and fine-tuning protein crystallization. Moreover, these results are also important for understanding the high stability of highly concentrated protein solutions (as they occur intracellularly) in organisms thriving under hydrostatic pressure conditions such as in the deep sea, where pressures up to the kbar-level are reached.

Grobelny, S.; Erlkamp, M.; Möller, J.; Tolan, M.; Winter, R.

2014-12-01

125

Study of Intermolecular Interactions of Acetophenone and Benzene at 303.15, 313.15 and 323.15 K  

Directory of Open Access Journals (Sweden)

Full Text Available The behaviour of mixture of acetophenone  and  benzene  as a function of temperature and composition  has been investigated by measuring sound velocity in conjunction with density at 303.15, 313.15and 323.15 K. Derived parameters computed from density (? and sound velocity (U have been used to determine excess molar volumes (VME, excess isentropic compressibilities (KSE and excess inter molecular free length (LfE.The excess functions have been discussed in terms of intermolecular interactions between the components of binary mixture. The validity of various theoretical approaches of liquids has been tested for the system by comparing theoretical sound speeds with those experimentally determined over the entire composition range in the temperature range 303.15-323.15K. The computed results have been fitted to the Redlich-Kister polynomial equation to estimate the smoothening coefficients and standard deviations for this system. The validity of various theoretical approaches of liquids has been tested for the system by comparing theoretical sound speeds with those experimentally determined over the entire composition range in the temperature303.15-323.15K.

K. Saravanakumar

2010-05-01

126

Intermolecular Interaction and the Extended Wormlike Chain Conformation of Chitin in NaOH/Urea Aqueous Solution.  

Science.gov (United States)

The intra- and intermolecular interactions of chitin in NaOH/urea aqueous system were studied by a combination of NMR measurements (including (13)C NMR, (23)Na NMR, and (15)N NMR) and differential scanning calorimetry. The results revealed that the NaOH and chitin formed a hydrogen-bonded complex that was surrounded by the urea hydrates to form a sheath-like structure, leading to the good dissolution. The optimal concentration range, in which chitin was molecularly dispersed in NaOH/urea aqueous, was found to investigate the chain conformation in the dilute solution with a combination of static and dynamic light scattering. The weight-average molecular weight (Mw), radii of gyration (?Rg?z), and hydrodynamic radii (?Rh?z) values of chitin were determined, and the structure-sensitive parameter (?) and persistent length (Lp) were calculated to be >2.0 and ?30 nm, respectively, suggesting an extended wormlike chain conformation. The visualized images from TEM, cryo-TEM, and AFM indicated that, chitin nanofibers were fabricated from the parallel aggregation of chitin chains in NaOH/urea system. This work would provide a theoretical guidance for constructing novel chitin-based nanomaterials via "bottom-up" method at the molecular level. PMID:25712045

Fang, Yan; Duan, Bo; Lu, Ang; Liu, Maili; Liu, Huili; Xu, Xiaojuan; Zhang, Lina

2015-04-13

127

Macrocyclic beta-sheet peptides that mimic protein quaternary structure through intermolecular beta-sheet interactions.  

Science.gov (United States)

This paper reports the design, synthesis, and characterization of a family of cyclic peptides that mimic protein quaternary structure through beta-sheet interactions. These peptides are 54-membered-ring macrocycles comprising an extended heptapeptide beta-strand, two Hao beta-strand mimics [JACS 2000, 122, 7654] joined by one additional alpha-amino acid, and two delta-linked ornithine beta-turn mimics [JACS 2003, 125, 876]. Peptide 3a, as the representative of these cyclic peptides, contains a heptapeptide sequence (TSFTYTS) adapted from the dimerization interface of protein NuG2 [PDB ID: 1mio]. 1H NMR studies of aqueous solutions of peptide 3a show a partially folded monomer in slow exchange with a strongly folded oligomer. NOE studies clearly show that the peptide self-associates through edge-to-edge beta-sheet dimerization. Pulsed-field gradient (PFG) NMR diffusion coefficient measurements and analytical ultracentrifugation (AUC) studies establish that the oligomer is a tetramer. Collectively, these experiments suggest a model in which cyclic peptide 3a oligomerizes to form a dimer of beta-sheet dimers. In this tetrameric beta-sheet sandwich, the macrocyclic peptide 3a is folded to form a beta-sheet, the beta-sheet is dimerized through edge-to-edge interactions, and this dimer is further dimerized through hydrophobic face-to-face interactions involving the Phe and Tyr groups. Further studies of peptides 3b-3n, which are homologues of peptide 3a with 1-6 variations in the heptapeptide sequence, elucidate the importance of the heptapeptide sequence in the folding and oligomerization of this family of cyclic peptides. Studies of peptides 3b-3g show that aromatic residues across from Hao improve folding of the peptide, while studies of peptides 3h-3n indicate that hydrophobic residues at positions R3 and R5 of the heptapeptide sequence are important in oligomerization. PMID:17419629

Khakshoor, Omid; Demeler, Borries; Nowick, James S

2007-05-01

128

Macrocyclic ?-Sheet Peptides that Mimic Protein Quaternary Structure through Intermolecular ?-Sheet Interactions  

Science.gov (United States)

This paper reports the design, synthesis, and characterization of a family of cyclic peptides that mimic protein quaternary structure through ?-sheet interactions. These peptides are 54-membered-ring macrocycles comprising an extended heptapeptide ?-strand, two Hao ?-strand mimics [JACS 2000, 122, 7654] joined by one additional ?-amino acid, and two ?-linked ornithine ?-turn mimics [JACS 2003, 125, 876]. Peptide 3a, as the representative of these cyclic peptides, contains a heptapeptide sequence (TSFTYTS) adapted from the dimerization interface of protein NuG2 [PDB ID: 1mio]. 1H NMR studies of aqueous solutions of peptide 3a show a partially folded monomer in slow exchange with a strongly folded oligomer. NOE studies clearly show that the peptide self-associates through edge-to-edge ?-sheet dimerization. Pulsed-field gradient (PFG) NMR diffusion coefficient measurements and analytical ultracentrifugation (AUC) studies establish that the oligomer is a tetramer. Collectively, these experiments suggest a model in which cyclic peptide 3a oligomerizes to form a dimer of ?-sheet dimers. In this tetrameric ?-sheet sandwich, the macrocyclic peptide 3a is folded to form a ?-sheet, the ?-sheet is dimerized through edge-to-edge interactions, and this dimer is further dimerized through hydrophobic face-to-face interactions involving the Phe and Tyr groups. Further studies of peptides 3b–3n, which are homologues of peptide 3a with 1–6 variations in the heptapeptide sequence, elucidate the importance of the heptapeptide sequence in the folding and oligomerization of this family of cyclic peptides. Studies of peptides 3b–3g show that aromatic residues across from Hao improve folding of the peptide, while studies of peptides 3h–3n indicate that hydrophobic residues at positions R3 and R5 of the heptapeptide sequence are important in oligomerization. PMID:17419629

Khakshoor, Omid; Demeler, Borries; Nowick, James S.

2008-01-01

129

Mixed layers of ?-lactoglobulin and SDS at air-water interfaces with tunable intermolecular interactions.  

Science.gov (United States)

Mixtures of ?-lactoglobulin (BLG) and sodium dodecyl sulfate (SDS) were studied at pH 3.8 and 6.7 under equilibrium conditions. At these pH conditions, BLG carries either a positive or a negative net charge, respectively, which enables tunable electrostatic interactions between anionic SDS surfactants and BLG proteins. For pH 3.8, vibrational sum-frequency generation (SFG) and ellipsometry indicate strong BLG-SDS complex formation at air-water interfaces that is caused by attractive electrostatic interactions. The latter complexes are already formed in the bulk solution which was confirmed by a thermodynamic study of BLG-SDS mixtures using isothermal titration calorimetry (ITC). For acidic conditions we determine from our ITC data an exothermal binding enthalpy of -40 kJ mol(-1). Increasing SDS/BLG molar ratios above 10 leads to a surface excess of SDS and thus to a charge reversal from a positive net charge with BLG as the dominating surface adsorbed species to a negatively charged layer with SDS as the dominating surface species. The latter is evidenced by a pronounced minimum in SFG intensities that is also accompanied by a phase change of O-H stretching bands due to a reorientation of H2O within the local electric field. This phase change which occurs at SDS/BLG molar ratio between 1 and 10 causes a polarity change in SFG intensities from BLG aromatic C-H stretching vibrations. Conclusions from SFG spectra are corroborated by ellipsometry which shows a dramatic increase in layer thicknesses at molar ratios where a charge reversal occurs. The formation of interfacial multilayers comprising SDS-BLG complexes is, thus, caused by cancellation of electrostatic interactions which leads to agglomeration at the interface. In contrast to pH 3.8, behavior of BLG-SDS mixtures at pH 6.7 is different due to repulsive electrostatic interactions between SDS and BLG which lead to a significantly reduced binding enthalpy of -17 kJ mol(-1). Finally, it has to be mentioned that SFG spectra show a coexistence of BLG and SDS molecules at the interface for BLG-SDS molar ratios > 2. PMID:24678897

Engelhardt, Kathrin; Weichsel, Ulrike; Kraft, Elena; Segets, Doris; Peukert, Wolfgang; Braunschweig, Björn

2014-04-17

130

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

131

Electronic structure, intermolecular interactions and electron emission dynamics via anion photoelectron imaging  

Science.gov (United States)

This dissertation explores the use of anion photoelectron imaging to interrogate electronic dynamics in small chemical systems with an emphasis on photoelectron angular distributions. Experimental ion generation, mass selection, laser photodetachment and photoelectron imaging were performed in a negative-ion photoelectron imaging spectrometer described in detail. Results for photodetachment from the simplest anion, H-, are used to illustrate fundamental principles of quantum mechanics and provide basic insight into the physics behind photoelectron imaging from a pedagogical perspective. This perspective is expanded by introducing imaging results for additional, representative atomic and small molecular anions (O-, NH2- and N3-) obtained at multiple photon energies to address the energy-dependence of photoelectron angular distributions both conceptually and semi-quantitatively in terms of interfering partial photoelectron waves. The effect of solvation on several of these species (H-, O-, and NH2 -) is addressed in photoelectron imaging of several series of cluster anions. The 532 and 355 nm energy spectra for H-(NH3) n and NH2-(NH3) n (n = 0-5) reveal that these species are accurately described as the core anion solute stabilized electrostatically by n loosely coordinated NH3 molecules. The photoelectron angular distributions for solvated H- deviate strongly from those predicted for unsolvated H- as the electron kinetic energy approaches zero, indicating a shift in the partial-wave balance consistent with both solvation-induced perturbation (and symmetry-breaking) of the H - parent orbital and photoelectron-solvent scattering. The photoelectron energy spectra obtained for the cluster series [O(N2O) n]- and [NO(N2O) n]- indicate the presence of multiple structural isomers of the anion cores, the former displaying sharp core-switching at n = 4, the latter isomer coexistence over the entire range studied. The photoelectron angular distributions for detachment from the O- (N2O)n and NO-(N 2O)n isomers deviate strongly from those expected for bare O- and NO-, respectively, in the region of an anionic shape resonance of N2O, suggesting resonant photoelectron-solvent scattering. Partial-wave models for two-centered photoelectron interference in photodetachment from dissociating I2 - is presented and discussed in the context of previous results. 10 New time-resolved photoelectron imaging results for I2 -, for both parallel and perpendicular pump and probe beam polarizations, are presented and briefly discussed. Finally, new ideas and directions are proposed.

Grumbling, Emily Rose

132

Fine structures in vibrational circular dichroism spectra of chiral molecules with rotatable hydroxyl groups and their application in the analysis of local intermolecular interactions  

Science.gov (United States)

The effect of hydroxyl group on vibrational circular dichroism is addressed. (-)-Menthol is investigated as a representative chiral molecule which has been widely used as a chiral starting material. Free rotation of the hydroxyl group in (-)-menthol allows it to exist in various conformations in solution. The variety of conformations inevitably affects local intermolecular interactions and the resultant efficiency of asymmetric syntheses. However, the precise relationship between the conformations and intermolecular interactions arising from rotation of the hydroxyl group has remained an unsolved issue despite the molecule's importance. Here, the conformations and interactions are investigated using vibrational circular dichroism (VCD). VCD is quite sensitive to slight differences in the conformation of chiral molecules and their local environment. We examined various conformers in (-)-menthol and compared the VCD spectrum with that of (-)-menthone. It revealed the rotation of the polar hydroxyl group sensitively affects the VCD activity, resulting in the emergence of various patterns in the corresponding VCD spectra, especially in the wavenumber regions at around 1064 cm-1 and 1254 cm-1. Among these regions, the latter one is further investigated to examine the feasibility of applying the sensitive response to the analysis on the local intermolecular environment. It includes solute-solvent interactions via hydroxyl groups, which is important for biomacromolecule structural stability and efficient stereoselective syntheses. As a consequence, distinctive fine structures in the VCD spectra, including an unpredicted band, are observed when varying temperature and concentration. Their possible assignment is also discussed.

Konno, Kohzo; Shiina, Isamu; Yui, Hiroharu

2013-03-01

133

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

134

Intermolecular potential energy surface and thermophysical properties of the CH4-N2 system  

Science.gov (United States)

A five-dimensional potential energy surface (PES) for the interaction of a rigid methane molecule with a rigid nitrogen molecule was determined from quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the CCSD(T) level of theory was utilized to compute a total of 743 points on the PES. The interaction energies were calculated using basis sets of up to quadruple-zeta quality with bond functions and were extrapolated to the complete basis set limit. An analytical site-site potential function with nine sites for methane and five sites for nitrogen was fitted to the interaction energies. The PES was validated by calculating the cross second virial coefficient as well as the shear viscosity and binary diffusion coefficient in the dilute-gas limit for CH4-N2 mixtures. An improved PES was obtained by adjusting a single parameter of the analytical potential function in such a way that quantitative agreement with the most accurate experimental values of the cross second virial coefficient was achieved. The transport property values obtained with the adjusted PES are in good agreement with the best experimental data.

Hellmann, Robert; Bich, Eckard; Vogel, Eckhard; Vesovic, Velisa

2014-12-01

135

Intermolecular potential energy surface and thermophysical properties of the CH4-N2 system.  

Science.gov (United States)

A five-dimensional potential energy surface (PES) for the interaction of a rigid methane molecule with a rigid nitrogen molecule was determined from quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the CCSD(T) level of theory was utilized to compute a total of 743 points on the PES. The interaction energies were calculated using basis sets of up to quadruple-zeta quality with bond functions and were extrapolated to the complete basis set limit. An analytical site-site potential function with nine sites for methane and five sites for nitrogen was fitted to the interaction energies. The PES was validated by calculating the cross second virial coefficient as well as the shear viscosity and binary diffusion coefficient in the dilute-gas limit for CH4-N2 mixtures. An improved PES was obtained by adjusting a single parameter of the analytical potential function in such a way that quantitative agreement with the most accurate experimental values of the cross second virial coefficient was achieved. The transport property values obtained with the adjusted PES are in good agreement with the best experimental data. PMID:25494743

Hellmann, Robert; Bich, Eckard; Vogel, Eckhard; Vesovic, Velisa

2014-12-14

136

Vibrational absorption, vibrational circular dichroism, and theoretical studies of methyl lactate self-aggregation and methyl lactate-methanol intermolecular interactions  

Science.gov (United States)

The infrared vibrational absorption (VA) and vibrational circular dichroism (VCD) spectra of methyl lactate in carbon tetrachloride and methanol have been measured in the 1000-1800 cm-1 region. Noticeable changes due to the solute self-aggregation and solvent-solute intermolecular hydrogen-bonding interactions have been detected in the reported spectra of the 2M methyl lactate solution in CCl4 and in methanol, respectively. Molecular dynamics simulations and a series of density functional theory (DFT) B3LYP/6-311++G??) and single point MP2/6-311++G?? energy calculations have been performed to identify and to model the explicit hydrogen-bonding interactions between the methanol solvent and the methyl lactate solute and among the methyl lactate molecules. Geometry search and optimization have been performed for the most stable conformers of the methyl lactate dimer and the methyl lactate-(methanol)N clusters, with N =1, 2, and 3. The relative single point MP2 energies among conformers are noticeably different from those obtained with DFT for the larger methyl lactate-methanol complexes. The VA and VCD spectra of these complexes have been simulated and compared to the corresponding experimental spectra. From the combined experimental and theoretical VA and VCD studies, it has been identified that both the methyl lactate monomer and dimer are the main species in the 2M CCl4 solution with 65% and 35% relative abundances, respectively, while the binary (55%) and quaternary (30%) methyl lactate-methanol clusters dominate in the 2M methanol solution, together with a smaller amount (15%) of the methyl lactate monomer. The effects of solute self-aggregation and solute-solvent interactions have been investigated in detail.

Liu, Yang; Yang, Guochun; Losada, Martin; Xu, Yunjie

2010-06-01

137

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

138

Vibrational relaxation of the symmetric #betta#6(A1)-vibration of thiophene in some liquid thiophene mixtures. Intermolecular interactions and motional characteristics  

International Nuclear Information System (INIS)

Raman isotropic line shapes of the #betta#6(A1)-vibration of thiophene are analysed by two characteristic parameters of their associated vibrational relaxation function for 19 different liquid mixtures, including isotopic dilution as well as changes of temperature and concentration. The data support the view that several intermolecular interactions are operative for relaxation with different relevant motions affecting them, both in resonant and in ''local field'' coupling. (author)

139

Intermolecular interactions and charge transfer transitions in aromatic hydrocarbon-tetracyanoethylene complexes.  

Science.gov (United States)

A comprehensive theoretical study of the electronically excited states in complexes between tetracyanoethylene (TCNE) and three aromatic electron donors, benzene, naphthalene and anthracene, was performed with a focus on charge transfer (CT) transitions. The results show that the algebraic diagrammatic construction method to second order (ADC(2)) provides excellent possibilities for reliable calculations of CT states. Significant improvements in the accuracy of the computed transition energies are obtained by using the scaled opposite-spin (SOS) variant of ADC(2). Solvent effects were examined on the basis of the conductor-like screening model (COSMO) which has been implemented recently in the ADC(2) method. The dielectric constant and the refractive index of dichloromethane have been chosen in the COSMO calculations to compare with experimental solvatochromic effects. The computation of optimized ground state geometries and enthalpies of formation has been performed at the second-order Møller-Plesset perturbation theory (MP2) level. By comparison with experimental data and with high-level coupled-cluster methods including explicitly correlated (F12) wave functions, the importance of the SOS approach is demonstrated for the ground state as well. In the benzene-TCNE complex, the two lowest electronic excitations are of CT character whereas in the naphthalene and anthracene TCNE complexes three low-lying CT states are observed. As expected, they are strongly stabilized by the solvent. Geometry optimization in the lowest excited state allowed the calculation of fluorescence transitions. Solvent effects lead to a zero gap between S1 and S0 for the anthracene-TCNE complex. Therefore, in the series of benzene-TCNE to anthracene a change from a radiative to a nonradiative decay mechanism to the ground state is to be expected. PMID:25156236

Aquino, Adélia A J; Borges, Itamar; Nieman, Reed; Köhn, Andreas; Lischka, Hans

2014-10-14

140

Molecular-beam study of the ammonia-noble gas systems: Characterization of the isotropic interaction and insights into the nature of the intermolecular potential  

Science.gov (United States)

We report new high resolution molecular beam experiments aimed at characterizing the intermolecular interaction in the NH3-Ng (Ng = He, Ne, Ar, Kr, Xe) weakly bound complexes. Integral cross section data are obtained over a sufficiently wide velocity range and with rotationally hot NH3 molecules to produce (except for the NH3-He case) a well resolved "glory" quantum interference pattern. Data analysis, carried out by employing a recently proposed potential model, allows unique information on the absolute scale of the intermolecular interaction to be obtained both at long range and at the equilibrium distance. An extensive and internally consistent comparison with the behavior of the corresponding Kr-Ng systems is exploited in order to identify those cases where an interaction component due to charge transfer effects provides an appreciable intermolecular bond stabilization that is clearly distinct from and must be added to the standard van der Waals plus induction picture. The results of the present investigation extend the phenomenology of perturbative charge transfer effects in gas phase complexes involving hydrogenated molecules.

Pirani, Fernando; Roncaratti, Luiz F.; Belpassi, Leonardo; Tarantelli, Francesco; Cappelletti, D.

2011-11-01

141

On the theory of the proton free induction decay and Hahn echo in polymer systems: The role of intermolecular magnetic dipole-dipole interactions and the modified Anderson-Weiss approximation  

Science.gov (United States)

The influence of the intermolecular magnetic dipole-dipole interaction on the free induction decay (FID) as well as on the Hahn-echo of proton spins in polymer melts is investigated. It is shown that for isotropic models of polymer dynamics, when polymer segment displacements do not correlate with an initial chain conformation, the influence of the intermolecular magnetic dipole-dipole interactions to the FID and Hahn echo is increasing more rapidly with evolution time than the corresponding influence of the intramolecular magnetic dipole-dipole interactions. On the other hand, the situation is inverted for the tube-reptation model: here the influence of the intramolecular magnetic dipole-dipole interactions to the FID and Hahn echo is increasing faster with time than the contribution from intermolecular interactions. A simple expression for the relative mean squared displacements of polymer segments from different chains is obtained from the intermolecular contribution to the FID. A modified Anderson-Weiss approximation, taking into account flip-flop transitions between different spins, is proposed and on that basis, the conditions for extracting the relative intermolecular mean squared displacements of polymer segments from the intermolecular contribution to the proton FID is established. Systematic investigations of intermolecular contributions, which were considered as an unimportant factor for FID and Hahn echo in polymer systems by most previous works, actually cannot be considered as negligible and opens a new dimension for obtaining information about polymer dynamics in the millisecond regime.

Fatkullin, N.; Gubaidullin, A.; Mattea, C.; Stapf, S.

2012-12-01

142

The role of the intermolecular magnetic dipole-dipole interaction in low frequency proton NMR in polymer melts  

Energy Technology Data Exchange (ETDEWEB)

The different contributions to the dynamic magnetic dipole-dipole correlation function, which is responsible for proton NMR phenomena like the spin-lattice relaxation, the free induction decay, the solid echo, etc., are analyzed. For the anisotropic tube-reptation model the relative weight of the intra-molecular contribution in the time dependent magnetic dipole-dipole correlation function should progressively increase with time, corresponding to lower resonance frequency, compared to the intermolecular contribution. For the isotropic n-Renormalized Rouse model the situation is opposite: with increasing of time/decreasing frequency the relative weight of the intermolecular contribution progressively increases and may eventually dominate. Theoretical estimations and analyses of published experimental results, connected with proton NMR spin-lattice relaxations in polymer melts, directly show that at times longer than and at frequencies below the regime, neglecting the intermolecular contributions to proton NMR phenomena in polymer melts, as had been done in the majority of scientific papers, is incorrect.

Fatkullin, Nail; Gubaidullin, Anvar [Kazan State University, Kazan, Tatarstan (Russian Federation); Stapf, Siegfried [Technische Universitaet Ilmenau (Germany). Dept. Technical Physics II; Kimmich, Rainer [University of Ulm (Germany). Sektion Kernresonanzspektroskopie

2010-07-01

143

The role of the intermolecular magnetic dipole-dipole interaction in low frequency proton NMR in polymer melts  

International Nuclear Information System (INIS)

The different contributions to the dynamic magnetic dipole-dipole correlation function, which is responsible for proton NMR phenomena like the spin-lattice relaxation, the free induction decay, the solid echo, etc., are analyzed. For the anisotropic tube-reptation model the relative weight of the intra-molecular contribution in the time dependent magnetic dipole-dipole correlation function should progressively increase with time, corresponding to lower resonance frequency, compared to the intermolecular contribution. For the isotropic n-Renormalized Rouse model the situation is opposite: with increasing of time/decreasing frequency the relative weight of the intermolecular contribution progressively increases and may eventually dominate. Theoretical estimations and analyses of published experimental results, connected with proton NMR spin-lattice relaxations in polymer melts, directly show that at times longer than and at frequencies below the regime, neglecting the intermolecular contributions to proton NMR phenomena in polymer melts, as had been done in the majority of scientific papers, is incorrect.

144

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

145

Collecting high-order interactions in an effective pairwise intermolecular potential using the hydrated ion concept: The hydration of Cf{sup 3+}  

Energy Technology Data Exchange (ETDEWEB)

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(H{sub 2}O){sub n}]{sup m+}(H{sub 2}O){sub ?} 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 H{sub 2}O for three of the intermolecular potentials predict an aquaion structure with coordination number close to 8 and average R{sub Cf??O} in the range 2.43–2.48 Å, whereas the fourth one is closer to 9 with R{sub 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; Pappalardo, Rafael R.; Marcos, Enrique Sánchez, E-mail: sanchez@us.es [Departmento de Química Física, Universidad de Sevilla, 41012 Seville (Spain); Hernández-Cobos, Jorge [Instituto de Ciencias Físicas, UNAM, Apartado Postal 48-3, 62251 Cuernavaca (Mexico)

2014-06-07

146

Driving unidirectional molecular rotary motors with visible light by intra- and intermolecular energy transfer from palladium porphyrin.  

Science.gov (United States)

Driving molecular rotary motors using visible light (530-550 nm) instead of UV light was achieved using palladium tetraphenylporphyrin as a triplet sensitizer. Visible light driven rotation was confirmed by UV/vis absorption, circular dichroism and (1)H NMR spectroscopy and the rotation was confirmed to be unidirectional and with similar photostationary states, despite proceeding via a triplet instead of a singlet excited state of the molecular motor. Energy transfer proceeds in both inter- and intramolecular fashion from the triplet state of the porphyrin to the motor. Stern Volmer plots show that the rate of intermolecular quenching of the porphyrin excited state by the molecular motor is diffusion-controlled. PMID:23036108

Cnossen, Arjen; Hou, Lili; Pollard, Michael M; Wesenhagen, Philana V; Browne, Wesley R; Feringa, Ben L

2012-10-24

147

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.

148

Intermolecular Interactions in the (CO2)2, N2-CO2 and CO-CO2 Complexes.  

Czech Academy of Sciences Publication Activity Database

Ro?. 69, ?. 1 (2004), s. 177-188. ISSN 0010-0765 R&D Projects: GA ?R GA203/00/0600 Institutional research plan: CEZ:AV0Z4040901 Keywords : van der Waals complexes * interaction energy * ab initio calculations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.062, year: 2004

Fišer, J.; Boublík, T.; Polák, Rudolf

2004-01-01

149

Influence of inter-molecular interactions on the elasto-damage mechanics of collagen fibrils: A bottom-up approach towards macroscopic tissue modeling  

Science.gov (United States)

In this paper, a novel modeling approach for describing the elasto-damage mechanical response of collagen fibrils is proposed. The model is developed by adopting a multiscale rationale that allows to consistently account for nanoscale mechanisms and to introduce model parameters with a clear biophysical/biochemical meaning. A detailed description of nanoscale inter-molecular interactions is considered, highlighting their great influence on fibril mechanical response. The model is successfully validated by comparisons with available data based on molecular dynamics simulations. Proposed results prove model capability to reproduce many well-established features of fibril mechanics, fully in agreement with available experimental evidence.

Marino, Michele; Vairo, Giuseppe

2014-12-01

150

Renewable energy liberation by nonthermal intermolecular bond dissociation in water and ethanol  

Science.gov (United States)

Prior indication that renewable energy can be extracted from hydrogen bonds in water has led to several investigations of the energy balance when bulk liquid is converted into micron scale droplets by directional (nonthermal) forces. The demonstration of this effect has previously involved pulsed high current arcs in water which produce large electrodynamic forces. Here, we show that renewable energy is also liberated during the creation of droplets by electrostatic forces in electrohydrodynamic atomization (electrospray) experiments. Using both ethanol and water, the energy outputs, primarily the droplet kinetic energy, were always greater than the energy inputs, implying that stored energy was liberated from the liquid. The energetics of generic chemical bonding are investigated to demonstrate that although this discovery was not publicly anticipated, it is consistent with conventional theory. This experimental breakthrough should have a major impact on the quest for renewable energy sources, capable of powering electricity generators.

Graneau, N.; Verdoold, S.; Oudakker, G.; Yurteri, C. U.; Marijnissen, J. C. M.

2011-02-01

151

INTER-MOLECULAR INTERACTIONS OF TETRAHYDROPYRAN + 1-BUTANOL BINARY SYSTEM AT T= (298.15, 303.15, 308.15, 313.15 & 318.15 K  

Directory of Open Access Journals (Sweden)

Full Text Available The evaluation of the different thermo dynamical parameters such as isentropic compressibility, molar volume, free length, acoustic impedance, internal pressure with their excess E E values, excess velocity (u , deviations of isentropic compressibility (? K , excess molar volume (V , s m E E E excess free length (L , excess acoustic impedance (Z and excess internal pressure (ð over the entire f i range of composition have been carried out at T = (298.15, 303.15, 308.15, 313.15 & 318.15 K from the measurements of ultrasonic velocity (u and density (ñ of pure & binary liquid mixtures of tetrahydropyran (THP with 1-butanol. The results thus obtained are discussed for molecular interaction. The nature of these values as seen from the plots of these ultrasonic parameters with the composition range indicates presence of the intermolecular interaction between the components of molecules of the mixture.

Anil Kumar K

2014-06-01

152

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.

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

1871-18-01

153

Intra- and intermolecular energy transfer of large molecules in solution after picosecond excitation  

International Nuclear Information System (INIS)

As an example of intramolecular vibrational redistribution experimental data of anthracene are presented. The absorption tail of anthracene at room temperature is compared with the transient absorption taken 7 ps after excitation with infrared photons of 3050 cm-1. The small shoulder seen at the room temperature curve results from three hot bands around 1400 cm-1. After IR-excitation of the CH stretching modes, the energy is rapidly redistributed and the absorption of the hot bands increases drastically. The experimental data suggest a rise of internal temperature of 170 K and the same increase of temperature is calculated when the energy of 3050 cm-1 is distributed over all the vibrational modes of anthracene. Similar findings were made for a number of other molecules

154

The "excited state C-C bond cleavage-luminescence" phenomenon of a biphenyl-substituted methylenecyclopropane triggered by intermolecular energy transfer from triplet benzophenone.  

Science.gov (United States)

Existence of the "excited state C-C bond cleavage-luminescence" phenomenon was demonstrated by utilizing intermolecular energy transfer from the excited-triplet benzophenone to 2,2-di(4-biphenylyl)-1-methylenecyclopropane (3). An excellent linear relationship between the intensity of the excitation laser light and that of luminescence clearly shows that formation of the corresponding excited trimethylenemethane biradical (3)4??* proceeds via a one-photon route. PMID:25267075

Matsui, Yasunori; Kido, Taiki; Ohta, Eisuke; Ikeda, Hiroshi

2014-11-21

155

A surface plasmon resonance study of the intermolecular interaction between Escherichia coli topoisomerase I and pBAD/Thio supercoiled plasmid DNA.  

Science.gov (United States)

To date, the bacterial DNA topoisomerases are one of the major target biomolecules for the discovery of new antibacterial drugs. DNA topoisomerase regulates the topological state of DNA, which is very important for replication, transcription and recombination. The relaxation of negatively supercoiled DNA is catalyzed by bacterial DNA topoisomerase I (topoI) and this reaction requires Mg(2+). In this report, we first quantitatively studied the intermolecular interactions between Escherichia coli topoisomerase I (EctopoI) and pBAD/Thio supercoiled plasmid DNA using surface plasmon resonance (SPR) technique. The equilibrium dissociation constant (Kd) for EctopoI-pBAD/Thio interactions was determined to be about 8 nM. We then studied the effect of Mg(2+) on the catalysis of EctopoI-pBAD/Thio reaction. A slightly higher equilibrium dissociation constant (~15 nM) was obtained for Mg(2+) coordinated EctopoI (Mg(2+)EctopoI)-pBAD/Thio interactions. In addition, we observed a larger dissociation rate constant (kd) for Mg(2+)EctopoI-pBAD/Thio interactions (~0.043 s(-1)), compared to EctopoI-pBAD/Thio interactions (~0.017 s(-1)). These results suggest that enzyme turnover during plasmid DNA relaxation is enhanced due to the presence of Mg(2+) and furthers the understanding of importance of the Mg(2+) ion for bacterial topoisomerase I catalytic activity. PMID:24530905

Tiwari, Purushottam Babu; Annamalai, Thirunavukkarasu; Cheng, Bokun; Narula, Gagandeep; Wang, Xuewen; Tse-Dinh, Yuk-Ching; He, Jin; Darici, Yesim

2014-03-01

156

Intra- and intermolecular Se···X (X = Se, O) interactions in selenium-containing heterocycles: 3-benzoylimino-5-(morpholin-4-yl)-1,2,4-diselenazole.  

Science.gov (United States)

In the selenium-containing heterocyclic title compound {systematic name: N-[5-(morpholin-4-yl)-3H-1,2,4-diselenazol-3-ylidene]benzamide}, C13H13N3O2Se2, the five-membered 1,2,4-diselenazole ring and the amide group form a planar unit, but the phenyl ring plane is twisted by 22.12 (19)° relative to this plane. The five consecutive N-C bond lengths are all of similar lengths [1.316 (6)-1.358 (6) Å], indicating substantial delocalization along these bonds. The Se···O distance of 2.302 (3) Å, combined with a longer than usual amide C=O bond of 2.252 (5) Å, suggest a significant interaction between the amide O atom and its adjacent Se atom. An analysis of related structures containing an Se-Se···X unit (X = Se, S, O) shows a strong correlation between the Se-Se bond length and the strength of the Se···X interaction. When X = O, the strength of the Se···O interaction also correlates with the carbonyl C=O bond length. Weak intermolecular Se···Se, Se···O, C-H···O, C-H···? and ?-? interactions each serve to link the molecules into ribbons or chains, with the C-H···O motif being a double helix, while the combination of all interactions generates the overall three-dimensional supramolecular framework. PMID:24816018

Linden, Anthony; Zhou, Yuehui; Heimgartner, Heinz

2014-05-01

157

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

158

Model for an RNA tertiary interaction from the structure of an intermolecular complex between a GAAA tetraloop and an RNA helix.  

Science.gov (United States)

In large structured RNAs, RNA hairpins in which the strands of the duplex stem are connected by a tetraloop of the consensus sequence 5'-GNRA (where N is any nucleotide, and R is either G or A) are unusually frequent. In group I introns there is a covariation in sequence between nucleotides in the third and fourth positions of the loop with specific distant base pairs in putative RNA duplex stems: GNAA loops correlate with successive 5'-C-C.G-C base pairs in stems, whereas GNGA loops correlate with 5'-C-U.G-A. This has led to the suggestion that GNRA tetraloops may be involved in specific long-range tertiary interactions, with each A in position 3 or 4 of the loop interacting with a C-G base pair in the duplex, and G in position 3 interacting with a U-A base pair. This idea is supported experimentally for the GAAA loop of the P5b extension of the group I intron of Tetrahymena thermophila and the L9 GUGA terminal loop of the td intron of bacteriophage T4 (ref. 4). NMR has revealed the overall structure of the tetraloop for 12-nucleotide hairpins with GCAA and GAAA loops and models have been proposed for the interaction of GNRA tetraloops with base pairs in the minor groove of A-form RNA. Here we describe the crystal structure of an intermolecular complex between a GAAA tetraloop and an RNA helix. The interactions we observe correlate with the specificity of GNRA tetraloops inferred from phylogenetic studies, suggesting that this complex is a legitimate model for intramolecular tertiary interactions mediated by GNRA tetraloops in large structured RNAs. PMID:7526219

Pley, H W; Flaherty, K M; McKay, D B

1994-11-01

159

The study of intermolecular energy transfers in electronic energy quenching for molecular collisions N2-N2, N2-O2, O2-O2  

Directory of Open Access Journals (Sweden)

Full Text Available Contributions of intermolecular electron energy transfers in the electronic quenching are calculated for molecular collisions N2(A3?u+, W3?u+N2(X1?g+, v=0, N2(A3?u++N2(X1?g+, v?0, N2(A3?u++O2(X3?g?, v=0–2, O2(a1?g, b1?g++O2(X3?g?, v=0–2. The calculation has allowed one to estimate the product branching ratios. It is shown that there is a dependence of the calculated rate coefficients on the vibrational excitation of N2(X1?g+ and O2(X3?g? molecules. In many cases, the calculated rate coefficients have a good agreement with available experimental data.

A. S. Kirillov

2008-05-01

160

Surface activity at the planar interface in relation to the thermodynamics of intermolecular interactions in the ternary system: maltodextrin-small-molecule surfactant-legumin.  

Science.gov (United States)

We report on the effect of potato maltodextrins with variable dextrose equivalent (Paselli SA-2, SA-6 and SA-10) on the surface behavior at the air-water interface of the mixture: legumin+small-molecule surfactant. Distinct in nature small-molecule surfactants (model: sodium salt of capric acid, Na-caprate; and commercially important: a citric acid ester of monoglyceride, CITREM) have been under our consideration. The role of the structure of both of the maltodextrins and the small-molecule surfactants in the effect studied has been elucidated by measurements in a bulk aqueous medium of the enthalpy of their interaction from mixing calorimetry, value of weight average molecular weight of the maltodextrins and the thermodynamics of the pair maltodextrin-solvent and maltodextrin-protein interactions from laser static light scattering. The combined data of mixing calorimetry and light scattering suggest some complex formation between the small-molecule surfactants and the maltodextrins. Predominantly hydrophobic interactions along with hydrogen bonding form the basis of the complexes. The effect of the maltodextrins on the thermodynamics of the protein heat denaturation and thereby on the protein conformational stability in the presence of the small-molecule surfactants has been studied by differential scanning calorimetry. The interrelation between the thermodynamics of intermolecular interactions in a bulk and the surface behavior at the planar air-water interface of the ternary systems (maltodextrin+legumin+small-molecule surfactant) has been elucidated by tensiometry. The effect of the maltodextrins on the surface activity of mixtures of legumin with the small-molecule surfactants is governed by the competitive in relation to the protein interactions with the small-molecule surfactants and a subsequent change in the thermodynamic properties of the both biopolymers, which are favorable to the ternary complex formation. PMID:11377947

Myasoedova, M S.; Semenova, M G.; Belyakova, L E.; Antipova, A S.

2001-07-01

161

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

162

Intermolecular inter-ligand interaction in mixed ligand complexes of lanthanides(III) involving histidine and some amino acids  

International Nuclear Information System (INIS)

The formation constant studies on binary and mixed ligand complexes of Pr (III) and Nd (III) involving histidine (hist) as primary ligand and ?-alanine (?-ala), valine (val) or leucine (leu) as secondary ligands have been undertaken to evaluate the extra-stabilization in the mixed ligand complexes due to possible occurrence of intramolecular inter-ligand interaction. Stability quantifying parameters (? log k and ?? log k) indicate significant inter-ligand interaction. (author)

163

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

164

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 A?, and with the complex in a linear configuration. At intermediate distances the surface is rather similar to that developed previously by Munteanu and Ferna?ndez (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.

Ferna?ndez, Berta; Henriksen, Christian

2013-01-01

165

Intra and inter-molecular interactions dictate the aggregation state of irinotecan co-encapsulated with floxuridine inside liposomes  

DEFF Research Database (Denmark)

PURPOSE: The inter/intramolecular interactions between drugs (floxuridine, irinotecan) and excipients (copper gluconate, triethanolamine) in the dual-drug liposomal formulation CPX-1 were elucidated in order to identify the physicochemical properties that allow coordinated release of irinotecan and floxuridine and maintenance of the two agents at a fixed, synergistic 1:1 molar ratio. METHODS: Release of irinotecan and floxuridine from the liposomes was assessed using an in vitro-release assay. Fluorescence, Nuclear Magnetic Resonance spectroscopy (NMR) and UV-Vis were used to characterize the aggregation state of the drugs within the liposomes. RESULTS: Coordinated release of the drugs from liposomes was disrupted by removing copper gluconate. Approximately 45% of the total irinotecan was detectable in the copper-containing CPX-1 formulation by NMR, which decreased to 19% without copper present in the liposomal interior. Formation of higher order, NMR-silent aggregates was associated with slower and uncoordinated irinotecan release relative to floxuridine and loss of the synergistic drug/drug ratio. Solution spectroscopy and calorimetry revealed that while all formulation components were required to achieve the highest solubility of irinotecan, direct drug-excipient binding interactions were absent. CONCLUSIONS: Long-range interactions between irinotecan, floxuridine and excipients modulate the aggregation state of irinotecan, allowing for simultaneous release of both drugs from the liposomes.

Dicko, Awa; Frazier, April A

2008-01-01

166

Ligand field and intermolecular interactions tuning the magnetic properties of spin-crossover Fe(II) polymer with 4,4?-bipyridine  

Science.gov (United States)

A new spin crossover coordination polymer (SCO-CPs) of Fe(II)-4,4?-bipyridine (4,4?-bipy) family: {Fe(4,4?-bipy)2(H2O)2}·(4,4?-bipy)· 8(H2O)·2(ClO4) (3), which displays half spin transitions between 100 and 300 K, has been synthesized and structurally characterized. Compound 3 featured with two-dimensional (2-D) grids connected by hydrogen bonds and ?…? packing between one-dimensional (1-D) chains, the 2-D grids expand to three-dimensional (3-D) architecture supported by a 'S-shaped holder' involving lattice 4-4?-bipy, water molecules and perchlorate anion. We compared 3 with the other two analogous complexes: ({Fe(4,4?-bipy) (H2O)2 (NCS)2}·4,4?-bipy, 1 and {Fe(4,4?-bipy)2(NCS)2}·mSolv, 2) through Hirshfeld surfaces analysis, which revealed that the low ligand field strength (NCS-) and lone-pair…H contacts contribute to the stabilization of HS (high-spin) state of the Fe(II) ion, while the high ligand field strength (4,4?-bipy) and strong intermolecular contacts (hydrogen bonds and ?…? packing interactions) make for the LS (low-spin) state.

Luo, Yang-Hui; Liu, Qing-Ling; Yang, Li-Jing; Ling, Yang; Wang, Wei; Sun, Bai-Wang

2015-02-01

167

A theoretical-experimental proposal, in teaching sequences about intermolecular interactions on teaching chemistry using varations of the test of adulteration in gasline and urucum dyes  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports presents the results of a research developed with students of the high school in the Dourados, Mato Grosso do Sul, with the objective of proposing a theoretical-experimental teaching sequences, potentially significant, approaching the theme Intermolecular Interactions. The teaching sequence was developed with 44 students of the last year of the high school, with the duration of 9 classes of 50 minutes. The methodology presents the characteristics of the qualitative research, being based on David Ausubel's theoretical. We used, as advance organizer, the test determination of the ethanol content in gasoline, adapting, along the experiments, to the use of the natural dyes of the urucum seeds communly used through the region the research was done. The instruments used to collect the information was through the use of questionnaires and observations of the classes. At the end 32 students presented arguments, developing in each stage, as well as in participation, as in classroom discussion, evidencing the evolution conceptual on the process of significant learning.

Ademir de Souza Pereira

2012-09-01

168

Self-assembly polymorphism of 2,7-bis-nonyloxy-9-fluorenone: solvent induced the diversity of intermolecular dipole-dipole interactions.  

Science.gov (United States)

In this present work, a scanning tunneling microscope (STM) operated under ambient conditions was utilized to probe the self-assembly behavior of 2,7-bis-nonyloxy-9-fluorenone (F-OC9) at the liquid-solid (l/s) interface. On the highly oriented pyrolytic graphite (HOPG) surface, two-dimensional (2D) polymorphism with diversity of intermolecular dipole interactions induced by solvent was found. Solvents ranged from hydrophilic solvating properties with high polarity, such as viscous alkylated acids, to nonpolar alkylated aromatics and alkanes. 1-Octanol and dichloromethane were used to detect the assembly of F-OC9 at the gas-solid (g/s) interface. The opto-electronic properties of F-OC9 were determined by UV-vis and fluorescence spectroscopy in solution. Our results showed that there were tremendous solvent-dependent self-assemblies in 2D ordering for the surface-confined target molecules. When a homologous series of alkanoic acids ranging from heptanoic to nonanoic acid were employed as solvents, the self-assembled monolayer evolved from low-density coadsorbed linear lamellae to a semi-circle-like pattern at relatively high concentrations, which was proven to be the thermodynamic state as it was the sole phase observed at the g/s interface after the evaporation of solvent. Moreover, by increasing the chain length of the alkylated acids, the weight of the carboxylic group, also being the group responsible for the dielectric properties, diminished from heptanoic to nonanoic acid, which could make the easier/earlier appearance of a linear coadsorption effect. However, this was not the case for nonpolar 1-phenyloctane and n-tetradecane: no concentration effect was detected. It showed a strong tendency to aggregate to generate coexistence of separate domains of different phases due to the fast nucleation sites. Furthermore, thermodynamic calculations indicated that the stable structural coexistence of the fluorenone derivative was attributed to synergistic intermolecular dipole-dipole and van der Waals (vdWs) forces at l/s interface. It is believed that the results are of significance to the fields of solvent induced polymorphism assembly and surface science. PMID:25554245

Cui, Lihua; Miao, Xinrui; Xu, Li; Hu, Yi; Deng, Wenli

2015-02-01

169

Intermolecular and surface forces  

CERN Document Server

This reference describes the role of various intermolecular and interparticle forces in determining the properties of simple systems such as gases, liquids and solids, with a special focus on more complex colloidal, polymeric and biological systems. The book provides a thorough foundation in theories and concepts of intermolecular forces, allowing researchers and students to recognize which forces are important in any particular system, as well as how to control these forces. This third edition is expanded into three sections and contains five new chapters over the previous edition.· starts fr

Israelachvili, Jacob N

2011-01-01

170

Intermolecular and Surface Forces  

CERN Document Server

This reference describes the role of various intermolecular and interparticle forces in determining the properties of simple systems such as gases, liquids and solids, with a special focus on more complex colloidal, polymeric and biological systems. The book provides a thorough foundation in theories and concepts of intermolecular forces, allowing researchers and students to recognize which forces are important in any particular system, as well as how to control these forces. This third edition is expanded into three sections and contains five new chapters over the previous edition.· starts fr

Israelachvili, Jacob N

2010-01-01

171

Basis Set Dependence of Interaction Energies Computed Using Composite Post-MP2 Methods.  

Czech Academy of Sciences Publication Activity Database

Ro?. 9, ?. 1 (2013), s. 330-337. ISSN 1549-9618 R&D Projects: GA ?R GBP208/12/G016 Institutional support: RVO:61388963 Keywords : plesset perturbation-theory * intermolecular interaction energies * density fitting approximations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.310, year: 2013

Platts, J. A.; Hill, J. G.; Riley, K. E.; ?ezá?, Jan; Hobza, Pavel

2013-01-01

172

Readout system for delay line detectors with a time stamp TDC and a small angle scattering study of intermolecular interactions in protein solutions  

Energy Technology Data Exchange (ETDEWEB)

The present work consists of two parts: The first part is a contribution to instrumentation and more particularly the development of a readout system for gas detectors used in small angle X-ray scattering (SAXS) and the second part covers the results of an investigation of interactions between proteins in solution. One aim of the instrumentation part was to investigate the role of fluorescence in gas proportional detector with delay line readout, a phenomenon that leads to events, unrelated to the actual scattering pattern. For this purpose a time stamp (TS-) TDC readout was developed that is able to detect simultaneous events in the detector by using all timing information in the anode and cathode signals (check-sum). It was found that the fluorescence of the gas clearly limits the spatial and time resolution in gas detection. The present observations confirm the influence of argon fluorescence on the point-spread function (PSF) and demonstrate that a rejection mechanism that analyses single events only cannot entirely eliminate these effects. The signal-to-noise ratio can, however, be improved by taking the drift time of the electrons and the check-sum of the signals into account. Drift time measurements are made possible by the unique ability of the TS-TDC to correlate the observation of scattered photons with individual radiation bunches in the storage ring. This feature could also facilitate time-resolved measurements with nanosecond-resolution. In the second part of this thesis gas detectors were used in a contribution to an important topic in biophysics: the study of intermolecular interactions in protein solutions. This was done by measuring the structure factors of protein solutions. According to the DLVO theory the main interactions between spherical particles are the hard-sphere interactions, a short range attraction, due to surface-surface forces, and a long range repulsion caused by the fact that the particles are charged. A computer program was written, which calculates the structure factors from the pair potentials and was shown to reproduce some results in the literature as well as all the main observations in our experiments. Several measurements were made on solutions of the proteins glucose oxidase and lysozyme under various conditions in order to investigate the interactions of these proteins in the presence of co-solutes such as salts, urea, TMAO, glycine or at different protein concentrations. The influence of variables like temperature and pH on the attractive and repulsive interactions and in particular the pair potentials was also studied. The main features of the structure factors observed in the protein concentration series are correctly predicted with the program. (orig.)

Niebuhr, M.

2004-07-01

173

Intermolecular interactions between salmon calcitonin, hyaluronate, and chitosan and their impact on the process of formation and properties of peptide-loaded nanoparticles.  

Science.gov (United States)

The principal aim of this work was to study the formulation of a ternary complex comprising salmon calcitonin (sCT), hyaluronate (HA), and chitosan (CS) in a nanoparticle (NP) format. As interactions between the constituents are possible, their presence and component mass mixing ratio (MMR) and charge mixing ratio (CMR) were investigated to tune the properties of NPs. Intermolecular interactions between sCT and HA as well as sCT and CS were studied by infrared spectroscopy (FTIR) and dynamic viscosity. The impact of MMR, CMR, and HA molecular weight on the sCT loading capacity in NPs and in vitro release properties was determined. sCT complexes to HA via electrostatic interactions and a support for hydrophobic interactions between sCT and HA as well as sCT and CS was found by FTIR. The sCT/HA complex is soluble but, depending on the mass mixing ratio between sCT and HA, NPs and microparticles were also formed indicative of associative phase separation between HA and sCT. The negatively charged HA/CS/sCT NPs were characterized by very high values (above 90%) of peptide association for the systems tested. Also, high sCT loading up to 50% were achieved. The peptide loading capacity and in vitro release properties were dependent on the NP composition. The zeta potential of the NPs without sCT was negative and ranging from -136 to -36 mV, but increased to -84 to -19 mV when the peptide was loaded. The particle size was found to be smaller and ranging 150-230 nm for sCT/NPs in comparison to NPs without sCT (170-260 nm). Short-term storage studies in liquid dispersions showed that the colloidal stability of NPs was acceptable and no release of sCT was observed for up to 3 days. In conclusion, a range of NP systems comprising sCT, HA, and CS was successfully developed and characterized. Such NPs may be considered as a suitable nanoparticulate format for the delivery of sCT. PMID:25447822

Umerska, Anita; Corrigan, Owen I; Tajber, Lidia

2014-12-30

174

Theoretical study of intermolecular energy transfer involving electronically excited molecules: He(1S) + H2(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 + H2(B 1?/sub u/+) was undertaken. Iterative natural orbital configuration interaction (CI) calculations were performed to obtain the interaction potential between He and H2(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 + H2(E,F 1?/sub g/+) and with He + H2(X 1?/sub g/+) and cause a local maximum and a deep minimum in the He + H2(B 1?/sub u/+) PES, respectively. The crossing with He + H2(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 H2(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

175

New Type of Dual Solid-State Thermochromism: Modulation of Intramolecular Charge Transfer by Intermolecular ?-? Interactions, Kinetic Trapping of the Aci-Nitro Group, and Reversible Molecular Locking  

Science.gov (United States)

When heated above room temperature, some crystalline polymorphs of the 1,3-bis(hydroxyalkylamino)-4,6-dinitrobenzenes (BDBn, n = 2-5), bis(hydroxyalkyl) analogues of the intramolecular charge-transfer molecule 1,3-diamino-4,6-dinitrobenzene, exhibit "dual" thermochromism: gradual color change from yellow to orange at lower temperatures, and sharp color change from orange to red at higher temperatures. These two thermochromic changes are related to different solid-state processes. When allowed to cool to room temperature, the yellow color of the thermochromic molecules with different alkyl length (n) is recovered with unexpectedly different kinetics, the order of the respective rate constants ranging from 10-7-10-6 s-1 for BDB2 to about 0.1 s-1 in the case of BDB3. The thermochromic mechanism and the reasons behind the different kinetics were clarified on the basis of detailed crystallographic characterization, kinetic thermoanalysis, and spectroscopic study of eight crystalline forms (seven polymorphs and one solvate). It was found that the polymorphism is due to the possibility of "locking" and "unlocking" of the alkyl arms by formation of a strong intramolecular hydrogen bond between the hydroxyl groups at their hydroxyl termini. The locking of BDB2, with shortest alkyl arms, is reversible and it can be controlled thermally; either of the two conformations can be obtained in the solid state by proper thermal treatment. By use of high temperature in situ single crystal X-ray diffraction analysis of BDB3, direct evidence was obtained that the gradual thermochromic change is related to increased distance and weakened ?-? interactions between the stacked benzene rings: the lattice expands preferably in the stacking direction, causing enhanced oscillator strength and red shift of the absorption edge of the intramolecular charge transfer transition. The second, sharp thermochromic change had been assigned previously to solid-solid phase transition triggered by intramolecular proton transfer of one amino proton to the nitro group, whereupon an aci-nitro form is thermally populated. Contrary to the numerous examples of solid thermochromic molecules based on either pericyclic reactions or keto-enol tautomerism, this system appears to be the first organic thermochromic family where the thermochromic change appears as an effect of intermolecular ?-? interactions and thermal intramolecular proton transfer to aromatic nitro group.

Naumov, Pan?e; Lee, Sang Cheol; Ishizawa, Nobuo; Jeong, Young Gyu; Chung, Ihn Hee; Fukuzumi, Shunichi

2009-09-01

176

Insights into the nature of intermolecular interactions in low-energy conformers of perindopril erbumine.  

Czech Academy of Sciences Publication Activity Database

Athens : World Scientific and Engineerin Academy and Society, 2009 - (Mastorakis, N.; Croitoru, A.; Balas, V.; Son, E.; Mladenov, V.), s. 190-193 ISBN 978-960-474-062-8. [WSEAS International Conference on Mathematics and Computers in Biology and Chemistry /10./. Prague (CZ), 23.03.2009-25.03.2009] R&D Projects: GA AV ?R IAA400500602; GA MŠk 2B08021 Institutional research plan: CEZ:AV0Z40500505 Keywords : perindopril erbumine * ab initio * conformation Subject RIV: CF - Physical ; Theoretical Chemistry

Czernek, Ji?í

177

Inhomogeneous and interacting vacuum energy  

OpenAIRE

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...

De-santiago, Josue; Wands, David; Wang, Yuting

2012-01-01

178

Desensitization of metastable intermolecular composites  

Science.gov (United States)

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

179

Intermolecular dispersion interactions of normal alkanes with rare gas atoms: van der Waals complexes of n-pentane with helium, neon, and argon  

International Nuclear Information System (INIS)

Interaction energies of normal pentane with three rare gas atoms (helium, neon, and argon) were calculated using ab initio methods: the second-order Moller-Plesset (MP2), the fourth-order Moller-Plesset (MP4), and coupled cluster with single and double substitutions with noniterative triple excitation (CCSD(T)) levels of theory. Dunning's correlation consistent basis sets up to aug-cc-pVQZ were applied. Eight profiles (246 points for each rare gas atom) of potential energy surface (PES) of all-trans (anti-anti) conformation of n-pentane were scanned. Optimal distances for complex formation were found. MP2 interaction energies at the basis set limit were evaluated by three different methods (Feller's, Helgaker's, and Martin's). The MP2 interaction energy at the basis set limit for a global minimum of n-pentane complex with argon was more than 400 cm-1, so formation of a stable complex (at least at low temperature) can be expected. A comparison with previously published data on propane complexes with rare gas atoms (both computational and experimental) was done. The MP4 level of theory was found to be sufficient for a description of C5H12 complexes with helium, neon, and argon

180

Intermolecular dispersion interactions of normal alkanes with rare gas atoms: van der Waals complexes of n-pentane with helium, neon, and argon  

Energy Technology Data Exchange (ETDEWEB)

Interaction energies of normal pentane with three rare gas atoms (helium, neon, and argon) were calculated using ab initio methods: the second-order Moller-Plesset (MP2), the fourth-order Moller-Plesset (MP4), and coupled cluster with single and double substitutions with noniterative triple excitation (CCSD(T)) levels of theory. Dunning's correlation consistent basis sets up to aug-cc-pVQZ were applied. Eight profiles (246 points for each rare gas atom) of potential energy surface (PES) of all-trans (anti-anti) conformation of n-pentane were scanned. Optimal distances for complex formation were found. MP2 interaction energies at the basis set limit were evaluated by three different methods (Feller's, Helgaker's, and Martin's). The MP2 interaction energy at the basis set limit for a global minimum of n-pentane complex with argon was more than 400 cm{sup -1}, so formation of a stable complex (at least at low temperature) can be expected. A comparison with previously published data on propane complexes with rare gas atoms (both computational and experimental) was done. The MP4 level of theory was found to be sufficient for a description of C{sub 5}H{sub 12} complexes with helium, neon, and argon.

Balabin, Roman M. [Gubkin Russian State University of Oil and Gas, 199991 Moscow (Russian Federation)], E-mail: balabin.r@gubkin.ru

2008-09-03

181

Intermolecular hydrogen bond energies in crystals evaluated using electron density properties: DFT computations with periodic boundary conditions.  

Science.gov (United States)

The hydrogen bond (H-bond) energies are evaluated for 18 molecular crystals with 28 moderate and strong O-H···O bonds using the approaches based on the electron density properties, which are derived from the B3LYP/6-311G** calculations with periodic boundary conditions. The approaches considered explore linear relationships between the local electronic kinetic G(b) and potential V(b) densities at the H···O bond critical point and the H-bond energy E(HB). Comparison of the computed E(HB) values with the experimental data and enthalpies evaluated using the empirical correlation of spectral and thermodynamic parameters (Iogansen, Spectrochim. Acta Part A 1999, 55, 1585) enables to estimate the accuracy and applicability limits of the approaches used. The V(b)-E(HB) approach overestimates the energy of moderate H-bonds (E(HB) X-ray diffraction experiments. PMID:22786749

Vener, M V; Egorova, A N; Churakov, A V; Tsirelson, V G

2012-11-01

182

Intermolecular potential energy surface, microwave and infrared spectra of the Kr-CO 2 complex from ab initio calculations  

Science.gov (United States)

We present a new potential energy surface for Kr-CO 2 which incorporates its dependence on the asymmetric Q3 normal mode with CO 2 in both ground ( ?3 = 0) and the first excited ( ?3 = 1) states were generated by integration of this potential over the Q3 coordinate. Each potential is found to have a T-shaped global minimum. The radial DVR/angular FBR method are applied to calculate the rovibrational energy levels. The calculated band origin shifts, microwave and infrared spectra are in good agreement with the available experiment values.

Chen, Rong; Zhu, Hua; Xie, Daiqian

2011-08-01

183

Effect of surface-plasmon polaritons on spontaneous emission and intermolecular energy-transfer rates in multilayered geometries  

Energy Technology Data Exchange (ETDEWEB)

We use a Green's tensor method to investigate the spontaneous emission rate of a molecule and the energy-transfer rate between molecules placed in two types of layered geometries: a slab geometry and a planar waveguide. We focus especially on the role played by surface-plasmon polaritons in modifying the spontaneous emission and energy-transfer rates as compared to free space. In the presence of more than one interface, the surface-plasmon polariton modes split into several branches, and each branch can contribute significantly to modifying the electromagnetic properties of atoms and molecules. Enhancements of several orders of magnitude both in the spontaneous emission rate of a molecule and the energy-transfer rate between molecules are obtained and, by tuning the parameters of the geometry, one has the ability to control the range and magnitude of these enhancements. For the energy-transfer rate interference effects between contributions of different plasmon-polariton branches are observed as oscillations in the distance dependence of this rate.

Marocico, C. A.; Knoester, J. [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747 AG Groningen (Netherlands)

2011-11-15

184

Intermolecular vibrations and spin--orbit predissociation dynamics of NeOH (X 2?)  

International Nuclear Information System (INIS)

Stimulated emission pumping of NeOH is used to access the bound intermolecular vibrational levels supported by the OH X 2?3/2+Ne potential energy surface as well as predissociative levels correlating with the spin--orbit excited state of OH X 2?1/2+Ne which lie more than 100 cm-1 above the dissociation limit. Intermolecular stretching intervals and rotor constants yield the radial dependence of the average interaction between Ne and OH X 2?3/2,1/2, while the spacings between angular levels provide information on the anisotropy of the potentials. The lifetime of spin--orbit predissociative levels is found to increase by a factor of 3 upon intermolecular stretching excitation, from 8.5 ps to more than 27 ps. This increase in lifetime is attributed to the fall-off in the coupling between the two spin--orbit states with increasing intermolecular separation distance. The dominant coupling for spin--orbit predissociation is provided by the difference potential, the change in the intermolecular potential when the unpaired electron of OH lies in or out of the NeOH plane. The energies, rotor constants, and lifetimes of the bound and predissociative NeOH levels observed experimentally are compared with theoretical calculations of these quantities based on ab initio potentials for Ne+OH X 2? by Yang and Alexander (accompanying paper). Remarkably good agreement is found between experiment agreement is found between experiment and theory, given the weakness of the Ne+OH X 2? interaction. copyright 1995 American Institute of Physics

185

Morphology-controlled self-assembled nanostructures of 5,15-di[4-(5-acetylsulfanylpentyloxy)phenyl]porphyrin derivatives. Effect of metal-ligand coordination bonding on tuning the intermolecular interaction.  

Science.gov (United States)

Novel metal-free 5,15-di[4-(5-acetylsulfanylpentyloxy)phenyl]porphyrin H2[DP(CH3COSC5H10O)2P] (1) and its zinc congener Zn[DP(CH3COSC5H10O)2P] (2) were designed and synthesized. Single-crystal X-ray diffraction (XRD) analysis confirmed the tetrapyrrole nature of these two compounds, revealing the existence of metal-ligand coordination bond between the carbonyl oxygen in the aryloxy side chain of meso-attached phenyl group in the porphyrin molecule with the zinc center of neighboring porphyrin molecule in the crystal structure of 2. This intermolecular Zn-O coordination bond induces the formation of a supramolecular chain structure in which the porphyrinato zinc moieties are arranged in a "head-to-tail" mode (J-aggregate), which is in contrast to a "face-to-face" stacking mode (H-aggregate) in the supramolecular structure formed depending on the C-H...pi interaction in the crystal of 1. Their self-assembling properties in MeOH and n-hexane were comparatively investigated by scanning electronic microscopy and XRD technique. Intermolecular pi-pi interaction of metal-free porphyrin 1 leads to the formation of hollow nanospheres and nanoribbons in MeOH and n-hexane, respectively. In contrast, introduction of additional Zn-O coordination bond for porphyrinato zinc complex 2 induces competition with intermolecular pi-pi interaction, resulting in nanostructures with nanorod and hollow nanosphere morphology in MeOH and n-hexane. The IR and XRD results clearly reveal the presence and absence of such metal-ligand coordination bond in the nanostructures formed from porphyrinato zinc complex 2 and metal-free porphyrin 1, respectively, which is further unambiguously confirmed by the single-crystal XRD analysis result for both compounds. Electronic absorption spectroscopic data on the self-assembled nanostructures reveal the H-aggregate nature in the hollow nanospheres and nanoribbons formed from metal-free porphyrin 1 due to the pi-pi intermolecular interaction between porphyrin molecules and J-aggregate nature in the nanorods and hollow nanospheres of 2 depending on the dominant metal-ligand coordination bonding interaction among the porphyrinato zinc molecules. The present result appears to represent the first effort toward controlling and tuning the morphology of self-assembled nanostructures of porphyrin derivatives via molecular design and synthesis through introduction of metal-ligand coordination bonding interaction. Nevertheless, availability of single crystal and molecular structure revealed by XRD analysis for both porphyrin derivatives renders it possible to investigate the formation mechanism as well as the molecular packing conformation of self-assembled nanostructures of these typical organic building blocks with large conjugated system in a more confirmed manner. PMID:19007122

Gao, Yingning; Zhang, Xiaomei; Ma, Changqin; Li, Xiyou; Jiang, Jianzhuang

2008-12-17

186

Intermolecular Adhesion in Conjugated Polymers  

CERN Document Server

Conjugated polymers are observed to aggregate in solution. To account for this observation we propose a inter-chain binding mechanism based on the intermolecular tunneling of the delocalized $\\pi$-electrons occurring at points where the polymers cross. This tunneling mechanism predicts specific bound structures of chain that depend on whether they are semiconducting or metallic. Semiconducting chains should form polyacene-like states exhibiting binding at every other site, while (doped) metallic chains can bind at each site. We also show that solitons co-localize with the intermolecular binding sites thereby strengthening the binding effect and investigate the conformational statistics of the resulting bimolecular aggregates.

Schmit, J D; Schmit, Jeremy D.; Levine, Alex J.

2006-01-01

187

Intermolecular Interaction in the Formaldehyde-Dimethyl Ether and Formaldehyde-Dimethyl Sulfide Complexes Investigated by Fourier Transform Microwave Spectroscopy and ab Initio Calculations.  

Science.gov (United States)

The ground-state rotational spectra of the formaldehyde-dimethyl ether (H2CO-DME) and formaldehyde-dimethyl sulfide (H2CO-DMS) complexes have been studied by Fourier transform microwave spectroscopy. The a-type and c-type rotational transitions have been assigned for the normal and deutrated formaldehyde-containing species of both complexes. In the case of H2CO-DME, doublets were observed with the splitting 10-300 kHz, whereas no such splittings were observed for H2CO-DMS, D2CO-DME, and D2CO-DMS. The observed rotational spectra were found consistent with a structure of Cs symmetry with DME or DMS bound to H2CO by two types of hydrogen bonds: C-H(DME/DMS)---O(H2CO) and O(DME)/S(DMS)---H-C(H2CO). The Rcm distances between the centers of mass of the component molecules in the H2CO-DME and H2CO-DMS complexes were determined to be 3.102 and 3.200 Å, respectively, which are shorter than those in most related complexes. The spectral and NBO analyses showed that H2CO-DMS has a stronger charge transfer interaction than H2CO-DME does and that the binding energy of H2CO-DMS is larger than that of H2CO-DME. PMID:25679958

Tatamitani, Yoshio; Kawashima, Yoshiyuki; Osamura, Yoshihiro; Hirota, Eizi

2015-03-12

188

Inter-molecular correlations in liquid Se2Br2  

International Nuclear Information System (INIS)

The structure of molecular liquid Se2Br2 was analyzed by means of reverse Monte Carlo structural modeling, using a calculation based on high-energy x-ray diffraction data. It was found that, between the optical isomers of L and D types, the number of L–D neighboring molecular pairs increases, while that of the L–L and D–D pairs decreases with increasing temperature. From this temperature dependence and from the relaxation mode analysis of quasi-elastic neutron scattering spectra, it is reasonable to assume that the presence of L–D pairs relates to genuine inter-molecular interactions while the L–L and D–D pairs appear due to geometrical packing of the gauche-shaped molecules. (paper)

189

Ab initio calculations of structures and interaction energies of toluene dimers including CCSD(T) level electron correlation correction  

Science.gov (United States)

The intermolecular interaction energy of the toluene dimer has been calculated with the ARS-F model (a model chemistry for the evaluation of intermolecular interaction energy between ARomatic Systems using Feller's method), which was formerly called as the AIMI model III. The CCSD(T) (coupled cluster calculations with single and double substitutions with noniterative triple excitations) interaction energy at the basis set limit has been estimated from the second-order Møller-Plesset perturbation interaction energy at the basis set limit obtained by Feller's method and the CCSD(T) correction term obtained using a medium-size basis set. The cross (C2) dimer has the largest (most negative) interaction energy (-4.08kcal/mol). The antiparallel (C2h) and parallel (CS) dimers (-3.77 and -3.41kcal/mol, respectively) are slightly less stable. The dispersion interaction is found to be the major source of attraction in the toluene dimer. The dispersion interaction mainly determines the relative stability of the stacked three dimers. The electrostatic interaction of the stacked three dimers is repulsive. Although the T-shaped and slipped-parallel benzene dimers are nearly isoenergetic, the stacked toluene dimers are substantially more stable than the T-shaped toluene dimer (-2.62kcal/mol). The large dispersion interaction in the stacked toluene dimers is the cause of their enhanced stability.

Tsuzuki, Seiji; Honda, Kazumasa; Uchimaru, Tadafumi; Mikami, Masuhiro

2005-04-01

190

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

191

Intermolecular potential functions from spectroscopic properties of weakly bound complexes  

Energy Technology Data Exchange (ETDEWEB)

Goal is to consolidate the information from high resolution spectroscopy of weakly bound cluster molecules through a theoretical model of intermolecular potential energy surfaces. The ability to construct analytic intermolecular potential functions that accurately predict the interaction energy between small molecules will have a major impact in chemistry, biochemistry, and biology. This document presents the evolution and capabilities of a potential function model developed here, and then describes plans for future developments and applications. This potential energy surface (PES) model was first used on (HCCH){sub 2}, (CO{sub 2}){sub 2}, HCCH - CO{sub 2}; it had to be modified to work with HX dimers and CO{sub 2}-HX complexes. Potential functions have been calculated for 15 different molecular complexes containing 7 different monomer molecules. Current questions, logical extensions and new applications of the model are discussed. The questions are those raised by changing the repulsion and dispersion terms. A major extension of the PES model will be the inclusion of induction effects. Projects in progress include PES calculations on (HCCH){sub 3}, CO{sub 2} containing complexes, (HX){sub 2}, HX - CO{sub 2}, CO{sub 2} - CO, (CO{sub 2}){sub 3}, and (OCS){sub 2}. The first PES calculation for a nonlinear molecule will be for water and ammonia complexes. Possible long-term applications for biological molecules are discussed. Differences between computer programs used for molecular mechanics and dynamics in biological systems are discussed, as is the problem of errors. 12 figs, 74 refs. (DLC)

Muenter, J.S.

1992-01-01

192

Evidence for Intermolecular Interactions between the Intracellular Domains of the Arabidopsis Receptor-Like Kinase ACR4, Its Homologs and the Wox5 Transcription Factor.  

Science.gov (United States)

Arabidopsis CRINKLY4 (ACR4) is a receptor-like kinase (RLK) involved in the global development of the plant. The Arabidopsis genome encodes four homologs of ACR4 that contain sequence similarity and analogous architectural elements to ACR4, termed Arabidopsis CRINKLY4 Related (AtCRRs) proteins. Additionally, a signaling module has been previously proposed including a postulated peptide ligand, CLE40, the ACR4 RLK, and the WOX5 transcription factor that engage in a possible feedback mechanism controlling stem cell differentiation. However, little biochemical evidence is available to ascertain the molecular aspects of receptor heterodimerization and the role of phosphorylation in these interactions. Therefore, we have undertaken an investigation of the in vitro interactions between the intracellular domains (ICD) of ACR4, the CRRs and WOX5. We demonstrate that interaction can occur between ACR4 and all four CRRs in the unphosphorylated state. However, phosphorylation dependency is observed for the interaction between ACR4 and CRR3. Furthermore, sequence analysis of the ACR4 gene family has revealed a conserved 'KDSAF' motif that may be involved in protein-protein interactions among the receptor family. We demonstrate that peptides harboring this conserved motif in CRR3 and CRK1are able to bind to the ACR4 kinase domain. Our investigations also indicate that the ACR4 ICD can interact with and phosphorylate the transcription factor WOX5. PMID:25756623

Meyer, Matthew R; Shah, Shweta; Zhang, J; Rohrs, Henry; Rao, A Gururaj

2015-01-01

193

Evidence for Intermolecular Interactions between the Intracellular Domains of the Arabidopsis Receptor-Like Kinase ACR4, Its Homologs and the Wox5 Transcription Factor  

Science.gov (United States)

Arabidopsis CRINKLY4 (ACR4) is a receptor-like kinase (RLK) involved in the global development of the plant. The Arabidopsis genome encodes four homologs of ACR4 that contain sequence similarity and analogous architectural elements to ACR4, termed Arabidopsis CRINKLY4 Related (AtCRRs) proteins. Additionally, a signaling module has been previously proposed including a postulated peptide ligand, CLE40, the ACR4 RLK, and the WOX5 transcription factor that engage in a possible feedback mechanism controlling stem cell differentiation. However, little biochemical evidence is available to ascertain the molecular aspects of receptor heterodimerization and the role of phosphorylation in these interactions. Therefore, we have undertaken an investigation of the in vitro interactions between the intracellular domains (ICD) of ACR4, the CRRs and WOX5. We demonstrate that interaction can occur between ACR4 and all four CRRs in the unphosphorylated state. However, phosphorylation dependency is observed for the interaction between ACR4 and CRR3. Furthermore, sequence analysis of the ACR4 gene family has revealed a conserved ‘KDSAF’ motif that may be involved in protein-protein interactions among the receptor family. We demonstrate that peptides harboring this conserved motif in CRR3 and CRK1are able to bind to the ACR4 kinase domain. Our investigations also indicate that the ACR4 ICD can interact with and phosphorylate the transcription factor WOX5. PMID:25756623

Meyer, Matthew R.; Shah, Shweta; Zhang, J.; Rohrs, Henry; Rao, A. Gururaj

2015-01-01

194

How resonance assists hydrogen bonding interactions: an energy decomposition analysis.  

Science.gov (United States)

Block-localized wave function (BLW) method, which is a variant of the ab initio valence bond (VB) theory, was employed to explore the nature of resonance-assisted hydrogen bonds (RAHBs) and to investigate the mechanism of synergistic interplay between pi delocalization and hydrogen-bonding interactions. We examined the dimers of formic acid, formamide, 4-pyrimidinone, 2-pyridinone, 2-hydroxpyridine, and 2-hydroxycyclopenta-2,4-dien-1-one. In addition, we studied the interactions in beta-diketone enols with a simplified model, namely the hydrogen bonds of 3-hydroxypropenal with both ethenol and formaldehyde. The intermolecular interaction energies, either with or without the involvement of pi resonance, were decomposed into the Hitler-London energy (DeltaEHL), polarization energy (DeltaEpol), charge transfer energy (DeltaECT), and electron correlation energy (DeltaEcor) terms. This allows for the examination of the character of hydrogen bonds and the impact of pi conjugation on hydrogen bonding interactions. Although it has been proposed that resonance-assisted hydrogen bonds are accompanied with an increasing of covalency character, our analyses showed that the enhanced interactions mostly originate from the classical dipole-dipole (i.e., electrostatic) attraction, as resonance redistributes the electron density and increases the dipole moments in monomers. The covalency of hydrogen bonds, however, changes very little. This disputes the belief that RAHB is primarily covalent in nature. Accordingly, we recommend the term "resonance-assisted binding (RAB)" instead of "resonance-assisted hydrogen bonding (RHAB)" to highlight the electrostatic, which is a long-range effect, rather than the electron transfer nature of the enhanced stabilization in RAHBs. PMID:17143867

Beck, John Frederick; Mo, Yirong

2007-01-15

195

Roles of Intramolecular and Intermolecular Interactions in Functional Regulation of the Hsp70 J-protein Co-Chaperone Sis1.  

Science.gov (United States)

Unlike other Hsp70 molecular chaperones, those of the eukaryotic cytosol have four residues, EEVD, at their C-termini. EEVD(Hsp70) binds adaptor proteins of the Hsp90 chaperone system and mitochondrial membrane preprotein receptors, thereby facilitating processing of Hsp70-bound clients through protein folding and translocation pathways. Among J-protein co-chaperones functioning in these pathways, Sis1 is unique, as it also binds the EEVD(Hsp70) motif. However, little is known about the role of the Sis1:EEVD(Hsp70) interaction. We found that deletion of EEVD(Hsp70) abolished the ability of Sis1, but not the ubiquitous J-protein Ydj1, to partner with Hsp70 in in vitro protein refolding. Sis1 co-chaperone activity with Hsp70?EEVD was restored upon substitution of a glutamic acid of the J-domain. Structural analysis revealed that this key glutamic acid, which is not present in Ydj1, forms a salt bridge with an arginine of the immediately adjacent glycine-rich region. Thus, restoration of Sis1 in vitro activity suggests that intramolecular interactions between the J-domain and glycine-rich region control co-chaperone activity, which is optimal only when Sis1 interacts with the EEVD(Hsp70) motif. However, we found that disruption of the Sis1:EEVD(Hsp70) interaction enhances the ability of Sis1 to substitute for Ydj1 in vivo. Our results are consistent with the idea that interaction of Sis1 with EEVD(Hsp70) minimizes transfer of Sis1-bound clients to Hsp70s that are primed for client transfer to folding and translocation pathways by their preassociation with EEVD binding adaptor proteins. These interactions may be one means by which cells triage Ydj1- and Sis1-bound clients to productive and quality control pathways, respectively. PMID:25687964

Yu, Hyun Young; Ziegelhoffer, Thomas; Osipiuk, Jerzy; Ciesielski, Szymon J; Baranowski, Maciej; Zhou, Min; Joachimiak, Andrzej; Craig, Elizabeth A

2015-04-10

196

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

Science.gov (United States)

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 connect the mol­ecules into chains propagating in [011], which are cross-linked via C—H?? inter­actions, generating a three-dimensional network. Aromatic ?–? stacking also occurs [shortest centroid–centroid separation = 3.6012?(11)?Å]. PMID:21754359

Betz, Richard; Gerber, Thomas; Hosten, Eric; Schalekamp, Henk

2011-01-01

197

Redetermined structure of diphenyl-phospho-nimidotriphenyl-phospho-rane: location of the hydrogen atoms and analysis of the inter-molecular inter-actions.  

Science.gov (United States)

The title compound, C(30)H(25)NOP(2), 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 mol-ecule. An intra-molecular C-H?O inter-action occurs. In the crystal, short C-H?O contacts connect the mol-ecules into chains propagating in [011], which are cross-linked via C-H?? inter-actions, generating a three-dimensional network. Aromatic ?-? stacking also occurs [shortest centroid-centroid separation = 3.6012?(11)?Å]. PMID:21754359

Betz, Richard; Gerber, Thomas; Hosten, Eric; Schalekamp, Henk

2011-05-01

198

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  

International Nuclear Information System (INIS)

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

199

Interfacial Interactions in Polyurethane Elastomer - Poly(vinyl chloride Blends  

Directory of Open Access Journals (Sweden)

Full Text Available An influence of chemical structure of hard segment in poly((urethane-ureas (PUU on intermolecular interactions in PUU/poly(vinyl chloride (PVC composite systems, as well as their morphology and mechanical properties has been studies. A formation of intra-and intermolecular interaction in the PUU/LiCl and PUU/PVC systems was determined by FTIR. Structural asymmetry and weakening intermolecular interactions in PUU promotes an increasing energy of interfacial H-bonds in PUU/PVC blends. Obtained nanocomposite materials have enhanced tensile properties.

Malysheva T.

2014-08-01

200

Interfacial Interactions in Polyurethane Elastomer - Poly(vinyl chloride) Blends  

OpenAIRE

An influence of chemical structure of hard segment in poly((urethane-urea)s (PUU) on intermolecular interactions in PUU/poly(vinyl chloride) (PVC) composite systems, as well as their morphology and mechanical properties has been studies. A formation of intra-and intermolecular interaction in the PUU/LiCl and PUU/PVC systems was determined by FTIR. Structural asymmetry and weakening intermolecular interactions in PUU promotes an increasing energy of interfacial H-bonds in PUU/PVC blends. Obtai...

Malysheva T.

2014-01-01

201

An NMR crystallography DFT-D approach to analyse the role of intermolecular hydrogen bonding and pi-pi interactions in driving cocrystallisation of indomethacin and nicotinamide  

OpenAIRE

Density functional theory (DFT) calculations using the Perdew-Burke- Ernzerhof (PBE) exchange-correlation functional are presented for a 1:1 cocrystal formed by indomethacin and nicotinamide (IND-NIC) as well as for crystal structures of the individual components. DFT-D approaches which correct the DFT energy for dispersion effects, specifically the Grimme (G06) and Tkatchenko-Scheffler (TS) schemes, are investigated: for geometry optimisation starting with crystal structures determined exper...

Dudenko, Dv; Yates, Jr; Harris, Kdm; Brown, Sp

2013-01-01

202

Bulk and molecular compressibilities of organic-inorganic hybrids [(CH?)?N]?MnX? (X = Cl, Br); role of intermolecular interactions.  

Science.gov (United States)

This work reports an X-ray diffraction, X-ray absorption, and Raman spectroscopy study of [(CH?)?N]?MnX? (X = Cl, Br) under pressure. We show that both compounds share a similar phase diagram with pressure. A P2?/c monoclinic structure describes precisely the [(CH?)?N]?MnCl? crystal in the 0.1-6 GPa range, prior to crystal decomposition and amorphization, while [(CH?)?N]?MnBr? can be described by a Pmcn orthorhombic structure in its stability pressure range of 0-3 GPa. These materials are attractive systems for pressure studies since they are readily compressible through the weak interaction between organic/inorganic [(CH?)?N?/MnX?²?] tetrahedra through hydrogen bonds and contrast with the small compressibility of both tetrahedra. Here we determine the equation-of-state (EOS) of each crystal and compare it with the corresponding local EOS of the MnX?²? and (CH?)?N? tetrahedra, the compressibility of which is an order and 2 orders of magnitude smaller than the crystal compressibility, respectively, in both chloride and bromide. The variations of the Mn-Cl bond distance obtained by extended X-ray absorption fine structure and the frequency of the totally symmetric ??(A?) Raman mode of MnCl?²? with pressure in [(CH?)?N]?MnCl? allowed us to determine the associated Grüneisen parameter (?(loc) = 1.15) and hence an accurate local EOS. On the basis of a local compressibility model, we obtained the Grüneisen parameters and corresponding variations of the intramolecular Mn–Br and C–N bond distances of MnBr?²? (?(loc) = 1.45) and (CH?)?N? (?(loc) = 3.0) in [(CH?)?N]?MnBr?. PMID:25244664

Barreda-Argüeso, Jose Antonio; Nataf, Lucie; Rodríguez-Lazcano, Yamilet; Aguado, Fernando; González, Jesús; Valiente, Rafael; Rodríguez, Fernando; Wilhelm, Heribert; Jephcoat, Andrew P

2014-10-01

203

Dynamics of interacting dark energy  

CERN Document Server

Dark energy and dark matter are only indirectly measured via their gravitational effects. It is possible that there is an exchange of energy within the dark sector, and this offers an interesting alternative approach to the coincidence problem. We consider two broad classes of interacting models where the energy exchange is a linear combination of the dark sector densities. The first class has been previously investigated, but we define new variables and find a new exact solution, which allows for a more direct, transparent and comprehensive analysis. The second class has not been investigated in general form before. We give general conditions on the parameters in both classes to avoid unphysical behavior (such as negative energy densities).

Caldera-Cabral, Gabriela; Urena-Lopez, L Arturo

2008-01-01

204

Intermolecular adhesion in conducting polymers  

CERN Document Server

We analyze the interaction of two conducting, charged polymer chains in solution using a minimal model for their electronic degrees of freedom. We show that a crossing of the two chains in which the polymers pass within Angstroms of each other leads to a decrease of the electronic energy of the combined system that is significantly larger than the thermal energy and thus promotes interchain aggregation. We consider the competition of this attractive interaction with the screened electrostatic repulsion and thereby propose a phase diagram for such polymers in solution; depending on the charge density and persistence length of the chains, the polymers may be unbound, bound in loose, braid-like structures, or tightly bound in a parallel configuration.

Schmit, J D; Schmit, Jeremy D.; Levine, Alex J.

2004-01-01

205

Experimental Proof of Resonant Auger Decay Driven Intermolecular Coulombic Decay  

Science.gov (United States)

Resonant Auger decay driven Intermolecular Coulombic Decay through synchrotron radiation in gas phase carbon monoxided dimers and nitrogen dimers has been studied. We report the first experiment where the low-energy ICD-electron has been measured in coincidence with the ionic fragments and Resonant Auger ICD has been proved experimentally.

Trinter, F.; Schöffler, M. S.; Kim, H.-K.; Sturm, F.; 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.

2014-04-01

206

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

207

The study of intermolecular energy transfers in electronic energy quenching for molecular collisions N{sub 2}-N{sub 2}, N{sub 2}-O{sub 2}, O{sub 2}-O{sub 2}  

Energy Technology Data Exchange (ETDEWEB)

Contributions of intermolecular electron energy transfers in the electronic quenching are calculated for molecular collisions N{sub 2}(A{sup 3}{sigma}{sub u}{sup +}, W{sup 3}{delta}{sub u})+N{sub 2}(X{sup 1}{sigma}{sub g}{sup +}, v=0), N{sub 2}(A{sup 3}{sigma}{sub u}{sup +})+N{sub 2}(X{sup 1}{sigma}{sub g}{sup +}, v{>=}0), N{sub 2}(A{sup 3}{sigma}{sub u}{sup +})+O{sub 2}(X{sup 3}{sigma}{sub g}{sup -}, v=0-2), O{sub 2}(a{sup 1}{delta}{sub g}, b{sup 1}{sigma}{sub g}{sup +})+O{sub 2}(X{sup 3}{sigma}{sub g}{sup -}, v=0-2). The calculation has allowed one to estimate the product branching ratios. It is shown that there is a dependence of the calculated rate coefficients on the vibrational excitation of N{sub 2}(X{sup 1}{sigma}{sub g}{sup +}) and O{sub 2}(X{sup 3}{sigma}{sub g}{sup -}) molecules. In many cases, the calculated rate coefficients have a good agreement with available experimental data. (orig.)

Kirillov, A.S. [Kola Science Centre RAS, Apatity (Russian Federation). Polar Geophysical Inst.

2008-07-01

208

Conformations and intermolecular interactions pattern in solid chloroxylenol and triclosan (API of anti-infective agents and drugs). A (35)Cl NQR, (1)H-(14)N NQDR, X-ray and DFT/QTAIM study.  

Science.gov (United States)

Two antibacterial and antifungal agents, chloroxylenol (4-chloro-3,5-dimethyl-phenol) and triclosan (5-chloro-2-(2',4'-dichlorophenoxy)-phenol), were studied experimentally in solid state with an X-ray, (35)Cl-nuclear quadrupole resonance (NQR) and (17)O-nuclear quadrupole double resonance (NQDR) spectroscopies and, theoretically, with the density functional theory/quantum theory of atoms in molecules (DFT/QTAIM). The crystallographic structure of triclosan, which crystallises in space group P31 with one molecule in the asymmetric unit [a?=?12.64100(10), b?=?12.64100(10), c = 6.71630(10) Å], was solved with an X-ray and refined to a final R-factor of 2.81% at room temperature. The NQR frequencies of (35)Cl and (17)O were detected with the help of the density functional theory (DFT) assigned to particular chlorine and oxygen sites in the molecules of both compounds. The NQR frequencies at (35)Cl sites in chloroxylenol and triclosan were found to be more differentiated than frequencies at the (17)O site. The former better describes the substituent withdrawing effects connected to ?-electron delocalization within the benzene rings and the influence of temperature; whereas, those at the (17)O site provide more information on O-H bond and intermolecular interactions pattern. The conformation adopted by diphenyl ether of triclosan in solid state was found to be typical of diphenyl ethers, but the opposite to those adopted when it was bound to different inhibitors. According to an X-ray study, temperature had no effect on the conformation of the diphenyl ring of triclosan, which was the same at 90?K and at room temperature (RT). The scattering of NQR frequencies reproduced by the DFT under assumption of the X-ray data at 90?K and RT is found to be a good indicator of the quality of resolution of the crystallographic structure. PMID:22354770

Latosi?ska, J N; Latosi?ska, M; Tomczak, M A; Seliger, J; Zagar, V; Maurin, J K

2012-02-01

209

On the thermodynamic characteristics of the benzene...Ar{sub 2} complex: An application of the ab initio intermolecular potential  

Energy Technology Data Exchange (ETDEWEB)

The benzene...Ar{sub 2} cluster was studied by constant energy molecular dynamics simulations using the ab initio intermolecular potential for the benzene...Ar interaction. The relative population of the energetically less favorable one-sided structure was found to higher that the population of the global minimum (two-sided structure). The preference of the energetically less stable structure was explained by the entropy effect. The thermodynamic functions (entropy, internal energy, and free energy) were calculated independently by integration of the canonical distribution function. 34 refs, 4 fig., 2 tab.

Vacek, J.; Hobza, P. [Institute of Physical Chemistry (Czechoslovakia)

1996-02-15

210

Desensitization and recovery of metastable intermolecular composites  

Science.gov (United States)

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

211

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

212

Nano-spectroscopic imaging of intermolecular structure, coupling and dynamics  

OpenAIRE

Molecular self-assembly, the function of biomembranes, and the performance of organic solar cells rely on molecular interactions on the nanoscale. The understanding and design of such intrinsic or engineered heterogeneous functional soft matter has long been impeded by a lack of spectroscopic tools with sufficient nanometer spatial resolution, attomolar sensitivity, and intermolecular spectroscopic specificity. We implement vibrational scattering-scanning near-field optical ...

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

2013-01-01

213

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

214

Molecular simulation of fluids with non-identical intermolecular potentials: Thermodynamic properties of 10-5 + 12-6 Mie potential binary mixtures  

Science.gov (United States)

General methods for combining interactions between particles characterised by non-identical intermolecular potentials are investigated. The combination methods are tested by performing molecular dynamics simulations to determine the pressure, energy, isochoric and isobaric heat capacities, thermal expansion coefficient, isothermal compressibility, Joule-Thomson coefficient, and speed of sound of 10-5 + 12-6 Mie potential binary mixtures. In addition to the two non-identical Mie potentials, mixtures are also studied with non-identical intermolecular parameters. The combination methods are compared with results obtained by simply averaging the Mie exponents. When either the energy or size parameters are non-identical, very significant differences emerge in the thermodynamic properties predicted by the alternative combination methods. The isobaric heat capacity is the thermodynamic property that is most affected by the relative magnitude of the intermolecular potential parameters and the method for combining non-identical potentials. Either the arithmetic or geometric combination of potentials provides a simple and effective way of performing simulations involving mixtures of components characterised by non-identical intermolecular potentials, which is independent of their functional form.

Stiegler, Thomas; Sadus, Richard J.

2015-02-01

215

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

216

Cyclin A probes by means of intermolecular sensitization of terbium-chelating peptides.  

Science.gov (United States)

Intermolecular sensitization of lanthanide ions was effectively implemented in the development of fluorescent sensors targeting cyclin A. A chelating unit has been conjugated to peptides containing a known cyclin A binding motif (CBM). Upon interaction of the modified terbium-chelating peptides with the cyclin A substrate recruitment groove, the Tb3+ ion is placed in the vicinity of the Trp217 side chain, which results in efficient intermolecular terbium sensitization and specific long wavelength fluorescent emission from the metal center. PMID:18593119

Pazos, Elena; Torrecilla, Daniel; Vázquez López, Miguel; Castedo, Luis; Mascareñas, José L; Vidal, Anxo; Vázquez, M Eugenio

2008-07-30

217

Intermolecular electronic and vibrational energy transfer from the single vibronic levels of p-difluorobenzene (1B2/sub u/) to cyclobutanone  

International Nuclear Information System (INIS)

An attempt has been made to measure the singlet--singlet electronic energy transfer rates from 17 single vibronic levels (SVL) of p-C6H4F2(1B2/sub u/) to cyclobutanone. No variation in the energy transfer cross sections have been found for the 17 SVL transitions, and an average value of 103 A2 (?sigma/sub c/2) is obtained. This value is nearly identical to the value obtained for the vibrationally relaxed, thermal levels. The reason for the lack of variation is suggested to be the consequence of rapid, intramolecular vibrational energy redistribution induced by collisional perturbation

218

Intermolecular electronic and vibrational energy transfer from the single vibronic levels of p-difluorobenzene (/sup 1/B/sub 2//sub u/) to cyclobutanone  

Energy Technology Data Exchange (ETDEWEB)

An attempt has been made to measure the singlet--singlet electronic energy transfer rates from 17 single vibronic levels (SVL) of p-C/sub 6/H/sub 4/F/sub 2/(/sup 1/B/sub 2//sub u/) to cyclobutanone. No variation in the energy transfer cross sections have been found for the 17 SVL transitions, and an average value of 103 A/sup 2/ (..pi..sigma/sub c//sup 2/) is obtained. This value is nearly identical to the value obtained for the vibrationally relaxed, thermal levels. The reason for the lack of variation is suggested to be the consequence of rapid, intramolecular vibrational energy redistribution induced by collisional perturbation.

Volk, L.J.; Lee, E.K.C.

1977-07-01

219

Interacting agegraphic tachyon model of dark energy  

OpenAIRE

Scalar-field dark energy models like tachyon are often regarded as an effective description of an underlying theory of dark energy. In this Letter, we implement the interacting agegraphic dark energy models with tachyon field. We demonstrate that the interacting agegraphic evolution of the universe can be described completely by a single tachyon scalar field. We thus reconstruct the potential as well as the dynamics of the tachyon field according to the evolutionary behavior...

Sheykhi, A.

2009-01-01

220

Hadronic interactions at intermediate energies  

International Nuclear Information System (INIS)

This report discusses research on the following topics: Hyperon physics at the AGS; strange dibaryons; muon decay into electron and gamma ray experiment; inelastic antineutron-proton scattering; antinucleon-nucleon interactions; and photoproduction of high transverse momentum jets. (LSP)

221

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

222

Interaction Energy Based Protein Structure Networks  

OpenAIRE

The three-dimensional structure of a protein is formed and maintained by the noncovalent interactions among the amino-acid residues of the polypeptide chain. These interactions can be represented collectively in the form of a network. So far, such networks have been investigated by considering the connections based on distances between the amino-acid residues. Here we present a method of constructing the structure network based on interaction energies among the amino-acid residues in the prot...

Vijayabaskar, M. S.; Vishveshwara, Saraswathi

2010-01-01

223

Interactions of Dark Energy with Other Components  

Science.gov (United States)

In this paper, we studied the interactions of dark energy with dark matter, black hole, and wormhole. It was shown that, in phantom case, the interaction terms make arise the new behaviors, such as avoidance from big rip, the decrease of black hole mass, and the increase of the wormhole throat size.

Kim, Sung-Won; Keum, Yong-Yeon

2010-04-01

224

Ion-surface interactions at low energies  

International Nuclear Information System (INIS)

Ion-surface interactions in the low energy range (around 1 keV) can be understood to some extent using simple models such as single two-body collision processes or undisturbed electronic energy levels. More detailed investigations show that multiple collisions, shadowing and different neutralization processes for bulk and surface scattering have to be considered. For a complete description of the interaction a three dimensional treatment is necessary, including trajectory dependent neutralization. (Author)

225

Large-scale compensation of errors in pairwise-additive empirical force fields: comparison of AMBER intermolecular terms with rigorous DFT-SAPT calculations.  

Science.gov (United States)

The intermolecular interaction energy components for several molecular complexes were calculated using force fields available in the AMBER suite of programs and compared with Density Functional Theory-Symmetry Adapted Perturbation Theory (DFT-SAPT) values. The extent to which such comparison is meaningful is discussed. The comparability is shown to depend strongly on the intermolecular distance, which means that comparisons made at one distance only are of limited value. At large distances the coulombic and van der Waals 1/r(6) empirical terms correspond fairly well with the DFT-SAPT electrostatics and dispersion terms, respectively. At the onset of electronic overlap the empirical values deviate from the reference values considerably. However, the errors in the force fields tend to cancel out in a systematic manner at equilibrium distances. Thus, the overall performance of the force fields displays errors an order of magnitude smaller than those of the individual interaction energy components. The repulsive 1/r(12) component of the van der Waals expression seems to be responsible for a significant part of the deviation of the force field results from the reference values. We suggest that further improvement of the force fields for intermolecular interactions would require replacement of the nonphysical 1/r(12) term by an exponential function. Dispersion anisotropy and its effects are discussed. Our analysis is intended to show that although comparing the empirical and non-empirical interaction energy components is in general problematic, it might bring insights useful for the construction of new force fields. Our results are relevant to often performed force-field-based interaction energy decompositions. PMID:20603660

Zgarbová, Marie; Otyepka, Michal; Sponer, Jirí; Hobza, Pavel; Jurecka, Petr

2010-09-21

226

Vacuum energies and multipole interactions  

Scientific Electronic Library Online (English)

Full Text Available 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].

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

2010-06-01

227

Monopole interaction and single-particle energies  

International Nuclear Information System (INIS)

The importance of the monopole component of effective NN interaction has been pointed out since 1960's in the context of energy difference between different shell-model configurations [1-3]. It has been more emphasized in recent studies on shell structure evolution in neutron-rich nuclei [4-6]. The definition of single-particle (s.p.) energy is not trivial, especially for open-shell nuclei. According to the prescription of Baranger [7], we derived an expression of s.p. energies by employing a shell-model sum rule technique [5]. The result is very simple and reasonable. The s.p. energy can be evaluated for any state by a sum of ?jcore with respect to the core nucleus and a part which arises from interaction between valence nucleons by calculating occupation numbers of s.p. orbits. The s.p. energies are determined only by the monopole strengths of NN interaction. This formulation allows us, for the first time, to discuss quantitatively changes of s.p. energies from a nucleus to another due to the monopole interaction, and, consequently, the evolution of shell structure. We have studied the monopole interaction in detail [6]. It is the lowest order term in the multipole expansion of NN interactions. The spin-tensor decomposition revealed that the monopole strengths are dominated by the triplet-even attraction of the central force, which contains second-order effects of the tensor force. The two-body monopole interaction is renormalized, as a very good approximation, to the one-body s.p. energies, which indicates that the above formulation of s.p. energies is consistent with the two-body interaction. The monopole, therefore, dominates the nuclear binding due to NN interactions. However, since the monopole interaction is expressed by number operators, it is diagonal with respect to shell-model configurations, and further binding is gained mainly by the quadrupole component. A study is under progress on the roles of central, tensor and spin-orbit components of NN interactions in a wide range of nuclear chart, with an emphasis on the monopole interaction.(author)

228

JACEE results on very high energy interactions  

International Nuclear Information System (INIS)

Direct observations of cosmic ray interactions in emulsion chambers of the JACEE experiment at energies above 1 TeV/nucleon are presented. An analysis of two decay of short lived particles produced in cosmic ray interactions is described. The known decay modes of bottom and charged particles do not account satisfactorily for the observations. This could possibly indicate a new decay channel of a heavy particle. The JACEE results support the hypothesis of existence of a long-flying component in cosmic ray showers. An interaction event was observed which may be the first direct observation of (mini)anticentauro interaction. (author)

229

An improved intermolecular potential for sulfur hexafluoride  

International Nuclear Information System (INIS)

Second virial coefficient data and viscosity were used to evaluate effective isotropic intermolecular potential functions proposed in the literature for sulfur hexafluoride. It was found that none of the potentials could predict the properties simultaneously. We have constructed a Morse--Morse--Spline--van der Waals (MMSV) potential which satisfactorily correlates second virial coefficient and viscosity data at the same time

230

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

231

Department of High Energy Nuclear Interactions - Overview  

International Nuclear Information System (INIS)

Full text: During the year 2001 the Department of High Energy Nuclear Interactions was involved in the following experiments and projects: * The PHOBOS experiment at the Relativistic Heavy Ion Collider (RHIC), Brookhaven National Laboratory (BNL), aimed at understanding the behavior of strongly interacting matter at high temperature and density. Quantum Chromodynamics, the fundamental theory of strong interactions, predicts that under these conditions, which may be probed in high energy heavy-ion collisions, a new state of matter will be formed, the quark-gluon plasma. The PHOBOS activities in the year 2001 concentrated on the studies of charged particle densities at mid-rapidity as a function of primary energy and centrality, the anisotropy of the final state azimuthal angle distribution and particle ratios at mid-rapidity in heavy ion interactions at the highest accelerator energies. * The objective of the PIERRE AUGER PROJECT is a high-statistics study of cosmic rays at energies above 1019 eV. The arrival directions, energies and mass composition of the cosmic rays will be measured in the effort to provide data necessary to determine the origin of these particles. The ICARUS experiment is designed for neutrino studies. The interactions and oscillations of the solar and atmospheric neutrinos will be studied. The search for proton decay and detection of neutrino bursts in case of a supernova event are also possible using the ICARUS detector. The data gathered in fixed target emulsion experiments E868/869 at BNL and EMU13 at CERN were used to investigate the nuclear fragmentation and particle production in heavy ion interactions as a function of primary energy and mass of the target nucleons. Some details on the research activities of the Department in the year 2001 are presented in Research Reports. (author)

232

Density functional theory calculations on dipeptide gallic acid interaction  

Science.gov (United States)

In the present investigation, an attempt has been made to study the interaction of dipeptides with gallic acid, using Becke3 parameter Lee Yang Parr (B3LYP) method employing 3-21G*, 6-31G* and 6-31+G* basis sets. The interaction energies of the dipeptide-gallic acid complexes are in the range of -5 to -18 kcal/mol depending on the mode of intermolecular complexation. Calculated molecular electrostatic potential (MESP) for the various intermolecular complexes revealed the electrostatic nature of the interaction. Qualitative estimations based on chemical hardness and chemical potential demonstrated fractional electron transfer from dipeptide to gallic acid.

Madhan, B.; Parthasarathi, R.; Subramanian, V.; Raghava Rao, J.; Nair, Balachandran Unni; Ramasami, T.

2003-02-01

233

Enantioselective catalysis of the intermolecular [2+2] photocycloaddition between 2-pyridones and acetylenedicarboxylates.  

Science.gov (United States)

Intermolecular [2+2] photocycloadditions represent the most versatile and widely applicable of photochemical reactions. For the first time, such intermolecular reactions have been carried out in a catalytic fashion using a chiral triplet sensitizer, with high enantioselectivity (up to 92%?ee). The low catalyst loading (2.5-5?mol%) underlines the high efficiency of the process both in terms of reaction acceleration and differentiation of the enantiotopic faces of the substrate. The substrate is anchored to the chiral catalyst through noncovalent interactions (hydrogen bonds), thus providing a chiral environment in which the enantioselective photocycloaddition proceeds. The densely functionalized products present numerous possibilities for further synthetic transformations. PMID:24888463

Maturi, Mark M; Bach, Thorsten

2014-07-14

234

High energy electron beam interaction with tantalum  

International Nuclear Information System (INIS)

Preliminary studies were performed on the interaction of high energy electron beams (HEEB) with commercially pure tantalum (Ta). Small Ta bars, nominally 2 x 0.5 x 0.1 cm were irradiated with HEEBs of energies ranging from 2.5 to 3 MeV, 1.5 kA, 1 to 2 micros pulse with a beam radius of 0.3 cm and larger. These HEEBs had a gaussian energy distribution. Following exposure in a vacuum, the bars were examined visually, with light optical microscopy and scanning electron microscopy which also provided energy dispersive x-rays (EDX) analysis. Weight and dimensional measurements were made on some of the bars. Based on the results of these examinations, a model for the interaction of HEEBs with Ta was developed and is presented

235

Binding energies of hypernuclei and ?-nuclear interactions  

International Nuclear Information System (INIS)

Variational calculations indicate that a reasonable description of ?p scattering and of ? separation energies can be obtained in terms of ?N plus dispersive and TPE ?NN forces. Results for the ?? interaction and for 6/sub ?/He obtained from an analysis of 10/sub ??/Be are discussed. Coulomb and ?N charge symmetry breaking effects in the A = 4 hypernuclei are discussed

236

Interacting Holographic Viscous Dark Energy Model  

OpenAIRE

In this manuscript, we present a generalization of the interacting holographic dark energy model using the viscous generalized Chaplygin gas. We also study the model by considering a dynamical Newton's constant $G$. Then we reconstruct the potential and the dynamics of the scalar field which describe the viscous Chaplygin cosmology.

Jamil, Mubasher; Farooq, M. Umar

2009-01-01

237

Monomer spectroscopic analysis and dimer interaction energies on N-(4-methoxybenzoyl)-2-methylbenzenesulfonamide by experimental and theoretical approaches.  

Science.gov (United States)

In this study, theoretical harmonic vibrational frequencies and geometric parameters of N-(4-methoxybenzoyl)-2-methylbenzenesulfonamide have been investigated by Hartree-Fock (HF), density functional theory (B3LYP hybrid functional) methods with 6-311++G (d,p) basis set, for the first time. Experimental FT-IR (400-4000cm(-1)) and Laser-Raman spectra (100-4000cm(-1)) of title compound in solid phase have been recorded. Interaction energies, N-H?O hydrogen bonds, C-H?O and aromatic ??? stacking interactions in dimer structures of the title compound have been evaluated by the calculation methods. The dimer calculations have aimed to present the efficacy and performance of M06-2X hybrid functional on the intermolecular interactions and more strongly bound systems for the corrected and interaction energy by the counterpoise correction procedure. The interaction energies by M06-2X approach give more stable results than HF and B3LYP, extremely. The more strongly bonds, especially, on N-H?O hydrogen bonds and ??? interaction for the both dimer structure have also supported that the M06-2X functional of density functional is more effective. PMID:25703361

Karakaya, Mustafa; Sert, Yusuf; Sreenivasa, Swamy; Suchetan, Parameshwar Adimoole; Ç?rak, Ça?r?

2015-05-01

238

Interacting vacuum energy in the dark sector  

Science.gov (United States)

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 a slow-roll power-law 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 show that they can be described as particular types of the modified Chaplygin gas.

Chimento, L. P.; Carneiro, S.

2015-03-01

239

Calculations on noncovalent interactions and databases of benchmark interaction energies.  

Science.gov (United States)

Although covalent interactions determine the primary structure of a molecule, the noncovalent interactions are responsible for the tertiary and quaternary structure of a molecule and create the fascinating world of the 3D architectures of biomacromolecules. For example, the double helical structure of DNA is of fundamental importance for the function of DNA: it allows it to store and transfer genetic information. To fulfill this role, the structure is rigid to maintain the double helix with a proper positioning of the complementary base, and floppy to allow for its opening. Very strong covalent interactions cannot fulfill both of these criteria, but noncovalent interactions, which are about 2 orders of magnitude weaker, can. This Account highlights the recent advances in the field of the design of novel wave function theory (WFT) methods applicable to noncovalent complexes ranging in size from less than 100 atoms, for which highly accurate ab initio methods are available, up to extended ones (several thousands atoms), which are the domain of semiempirical QM (SQM) methods. Accurate interaction energies for noncovalent complexes are generated by the coupled-cluster technique, taking single- and double-electron excitations iteratively and triple-electron excitation perturbatively with a complete basis set description (CCSD(T)/CBS). The procedure provides interaction energies with high accuracy (error less than 1 kcal/mol). Because the method is computationally demanding, its application is limited to complexes smaller than 30 atoms. But researchers would also like to use computational methods to determine these interaction energies accurately for larger biological and nanoscale structures. Standard QM methods such as MP2, MP3, CCSD, or DFT fail to describe various types of noncovalent systems (H-bonded, stacked, dispersion-controlled, etc.) with comparable accuracy. Therefore, novel methods are needed that have been parametrized toward noncovalent interactions, and existing benchmark data sets represent an important tool for the development of new methods providing reliable characteristics of noncovalent clusters. Our laboratory developed the first suitable data set of CCSD(T)/CBS interaction energies and geometries of various noncovalent complexes, called S22. Since its publication in 2006, it has frequently been applied in parametrization and/or verification of various wave function and density functional techniques. During the intense use of this data set, several inconsistencies emerged, such as the insufficient accuracy of the CCSD(T) correction term or its unbalanced character, which has triggered the introduction of a new, broader, and more accurate data set called the S66 data set. It contains not only 66 CCSD(T)/CBS interaction energies determined in the equilibrium geometries but also 1056 interaction energies calculated at the same level for nonequilibrium geometries. The S22 and S66 data sets have been used for the verification of various WFT methods, and the lowest RMSE (S66, in kcal/mol) was found for the recently introduced SCS-MI-CCSD/CBS (0.08), MP2.5/CBS (0.16), MP2.X/6-31G* (0.27), and SCS-MI-MP2/CBS (0.38) methods. Because of their computational economy, the MP2.5 and MP2.X/6-31G* methods can be recommended for highly accurate calculations of large complexes with up to 100 atoms. The evaluation of SQM methods was based only on the S22 data set, and because some of these methods have been parametrized toward the same data set, the respective results should be taken with caution. For really extended complexes such as protein-ligand systems, only the SMQ methods are applicable. After adding the corrections to the dispersion energy and H-bonding, several methods exhibit surprisingly low RMSE (even below 0.5 kcal/mol). Among the various SMQ methods, the PM6-DH2 can be recommended because of its computational efficiency and it can be used for optimization (which is not the case for other SQM methods). The PM6-DH2 is the base of our novel scoring function used in in silico drug design. PMID:22225511

Hobza, Pavel

2012-04-17

240

Multidimensional intermolecular dynamics from tunable far-infrared laser spectroscopy: Angular-radial coupling in the intermolecular potential of argon--H2O  

International Nuclear Information System (INIS)

Five new vibration--rotation tunneling states of Ar--H2O [the ? and ?(111) and the ? and ?(212) internal rotor states and the n=1, ?(101) stretching-internal rotor combination level] have been accessed by tunable far-infrared laser spectroscopy. The measured vibrational band origins of transitions to these states are within 2% of predictions made from an anisotropic three-dimensional intermolecular potential surface (denoted AW1) derived from a nonlinear least-squares fit to previous far-infrared spectral data [J. Phys. Chem. 94, 7991(1990)]. This provides strong evidence that the AW1 intermolecular potential surface incorporates much of the essential physics of the intermolecular forces which bind the cluster. However, larger deviations from the predictions are found in the observed rotational term values. A detailed analysis of these deviations clearly demonstrates the need for even stronger angular-radial coupling in the Ar--H2O intermolecular potential than the already substantial coupling present in the AW1 surface. Specifically, the presently observed ?(111) state and the n=1, ?(000) state are found to be approximately 65:35 mixtures of the basis states which represent pure stretching and internal rotation. The ?(212) level is found to be mixed just as strongly with n=2, ?(101). The formalism for accurately deperturbing vibration--rotation--tunneling stateration--rotation--tunneling states coupled by Coriolis interactions used in the above analysis is presented

241

Binding energies of hypernuclei and hypernuclear interactions  

Energy Technology Data Exchange (ETDEWEB)

In part 1 the effect of nuclear core dynamics on the binding energies of {Lambda} 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 {Lambda} single-particle energy in terms of basic {Lambda}-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 {Lambda}NN forces are required. Also in this framework they discuss core polarization for medium and heavier hypernuclei.

Bodmer, A.R. [Argonne National Lab., IL (United States)]|[Univ. of Illinois, Chicago, IL (United States). Dept. of Physics; Murali, S.; Usmani, Q.N. [Jamia Millia Islamia, New Delhi (India). Dept. of Physics

1996-05-01

242

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

243

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(II)Pc and Fe(III)Pc 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(II)Pc-p-CHL system is found to be higher than that for Fe(III)Pc-p-CHL system. This observation is well supported by the results of fluorescence quenching studies and the association constants calculated for Fe(II)Pc-p-CHL system is 4.2 × 10(3) mol L(-1) and that for Fe(III)Pc-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. PMID:22074888

Balraj, Chellamuthu; Elango, Kuppanagounder P

2012-02-01

244

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 “on” symbol (or “1”), which costs one unit of energy, or an “off” signal (or “0”), which does not require any energy expenditure. Upon reception of a “1” signal, the recipient node “harvests”, 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 Terms— Two-way channel, interactive communication, energy transfer, energy harvesting.

Popovski, Petar; Fouladgar, A. M.

2013-01-01

245

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 atosingle 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

246

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

Energy Technology Data Exchange (ETDEWEB)

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 {delta}-methyl groups of isoleucine, while the other component is uniformly {sup 13}C-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 IIA{sup Glc}-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 {approx}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.

Tang, Chun; Clore, G. Marius [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States)], E-mail: mariusc@intra.niddk.nih.gov

2006-09-15

247

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

248

Direct detection of intermolecular forces by atomic force microscopy  

Science.gov (United States)

The phenomenon of adhesion appears in various applications of everyday life, ranging from PostIt Notes(TM) and Scotch Tape(TM), to the assembly of aircraft and space shuttles. However, adhesion on the molecular scale is fundamentally different from the adhesion that we experience in the macroscopic world. While macroscopic objects require special adhesives or glues to bind them together, microscale and nanoscale objects and molecules commonly have a high affinity to adhere to each other. A detailed description of intermolecular forces is therefore of key importance in order to understand a wide range of phenomena, ranging from macroscopic properties of materials to molecular recognition. Two key aspects of the atomic force microscope (AFM), namely its sensitivity to sub-nanoNewton forces and its very sharp probe, offer the opportunity to measure interactions between very small numbers of molecules. Through chemical tailoring of both substrates and AFM probes with self-assembled monolayers (SAMs), measurements of forces acting between specific functional groups can be measured. Furthermore, the force required to rupture a single chemical bond can be obtained by a detailed analysis of the histograms of rupture forces. A new model was derived to examine the relationship between the various experimental variables and the shape of histograms of rupture forces when discrete chemical bonds are formed between the AFM probe and substrate. Calculations based on the model demonstrated that in measurements aimed at detecting single bond rupture forces, strict limits are put on the size of the AFM probe, the relative magnitude of the interfacial energies and the bond formation probability. These results were used in two experimental systems where the single bond rupture force was successfully measured: (i) the abstraction of a single Au-S complex from an Au coated AFM probe; and (ii) the rupture of a single charge-transfer (CT) complex between tetramethylphenylenediamine (TMPD) and tetracyanoquinodimethane (TCNQ). Measurements involving only one molecule at a time were conducted using polymer chains chemically grafted to the AFM probe and substrate. In these measurements, the effect of the solvent on the elasticity of the poly-ethylene-propylene oligomers was directly observed in the force-elongation profile.

Skulason, Hjalti

249

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

250

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

251

Nano-spectroscopic imaging of intermolecular structure, coupling and dynamics  

CERN Document Server

Molecular self-assembly, the function of biomembranes, and the performance of organic solar cells rely on molecular interactions on the nanoscale. The understanding and design of such intrinsic or engineered heterogeneous functional soft matter has long been impeded by a lack of spectroscopic tools with sufficient nanometer spatial resolution, attomolar sensitivity, and intermolecular spectroscopic specificity. We implement vibrational scattering-scanning near-field optical microscopy ($s$-SNOM) in a multi-spectral modality with unprecedented spectral precision to investigate the structure-function relationship in nano-phase separated block-copolymers. We use a vibrational resonance as a sensitive reporter of the local chemical environment and resolve, with few nanometer spatial resolution and 0.2 cm$^{-1}$ spectral precision, spectral Stark shifts and line broadening correlated with molecular-scale morphologies. By creating images of solvatochromic vibrational shifts we discriminate local variations in elect...

Pollard, Benjamin; Hinrichs, Karsten; Raschke, Markus B

2013-01-01

252

Intermolecular Coulomb Decay at Weakly Coupled Heterogeneous Interfaces  

Science.gov (United States)

Surface ejection of H+(H2O)n=1-8 from low energy electron irradiated water clusters adsorbed on graphite and graphite with overlayers of Ar, Kr or Xe results from intermolecular Coulomb decay (ICD) at the mixed interface. Inner valence holes in water (2a1-1), Ar (3s-1), Kr (4s-1), and Xe (5s-1) correlate with the cluster appearance thresholds and initiate ICD. Proton transfer occurs during or immediately after ICD and the resultant Coulomb explosion leads to H+(H2O)n=1-8 desorption with kinetic energies that vary with initiating state, final state, and interatomic or molecular distances.

Grieves, Gregory A.; Orlando, Thomas M.

2011-07-01

253

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

254

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

255

Redshift drift exploration for interacting dark energy  

CERN Document Server

By detecting redshift drift in the spectra of Lyman-$\\alpha$ forest of distant quasars, Sandage-Loeb (SL) test directly measures the expansion of the universe, covering the "redshift desert" of $2 \\lesssim z \\lesssim5$. Thus this method is definitely an important supplement to the other geometric measurements and will play a crucial role in cosmological constraints. In this paper, we quantify the ability of SL test signal by a CODEX-like spectrograph for constraining interacting dark energy. Four typical interacting dark energy models are considered: (\\romannumeral1) $Q=\\gamma H\\rho_c$, (\\romannumeral2) $Q=\\gamma H\\rho_{de}$, (\\romannumeral3) $Q=\\gamma H_0\\rho_c$, and (\\romannumeral4) $Q=\\gamma H_0\\rho_{de}$. The results show that for all the considered interacting dark energy models, relative to the current joint SN+BAO+CMB+$H_0$ observations, the constraints on $\\Omega_m$ and $H_0$ would be improved by about 60\\% and 30--40\\%, while the constraints on $w$ and $\\gamma$ would be slightly improved, with a 30-y...

Geng, Jia-Jia; Zhang, Jing-Fei; Zhang, Xin

2015-01-01

256

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 methyl. A [...] bout 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.

257

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

258

[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

259

High energy photon-neutrino interactions  

Science.gov (United States)

A general decomposition of the amplitudes for the 2-->2 processes ??-->?? and ??-->??¯ is obtained using gauge invariance and Bose symmetry. The restrictions implied by this decomposition are investigated for the reaction ??-->??¯ by computing the one-loop helicity amplitudes in the standard model. In the center of mass, where s=2?, the cross section grows roughly as ?6 up to the threshold for W-boson production, s=2mW. Astrophysical implications of very high energy photon-neutrino interactions are discussed.

Abbasabadi, Ali; Devoto, Alberto; Dicus, Duane A.; Repko, Wayne W.

1999-01-01

260

High energy photon-neutrino interactions  

International Nuclear Information System (INIS)

A general decomposition of the amplitudes for the 2?2 processes ????? and ???? bar ? is obtained using gauge invariance and Bose symmetry. The restrictions implied by this decomposition are investigated for the reaction ???? bar ? by computing the one-loop helicity amplitudes in the standard model. In the center of mass, where ? (s) =2?, the cross section grows roughly as ?6 up to the threshold for W-boson production, ? (s) =2mW. Astrophysical implications of very high energy photon-neutrino interactions are discussed. copyright 1998 The American Physical Society

261

High energy photon-neutrino interactions  

International Nuclear Information System (INIS)

A general decomposition of the amplitudes for the 2 ? 2 processes ?? ? ?? and ?? ? ? bar ? is obtained using gauge invariance and Bose symmetry. The restrictions implied by this decomposition are investigated for the reaction ?? ? ? bar ? by computing the one-loop helicity amplitudes in the standard model. In the center of mass, where ?s = 2?, the cross section grows roughly as ?6 up to the threshold for W-boson production, ?s 2mW. Astrophysical implications of very high energy photon-neutrino interactions are discussed

262

Deuterium-substituted water-ammonia mixed trimer clusters, (H2O)n-3(NH3)n (n = 0,1,2,3): Interaction energy, hydrogen bond structures, and Mulliken population  

International Nuclear Information System (INIS)

The interaction energies and hydrogen bond structures of water-ammonia mixed trimer clusters, (H2O)n-3(NH3)n (n = 0, 1, 2, 3), were analyzed by means of a multi-component molecular orbital method, which directly accounts the quantum effects of protons. We found that the protonic quantum effects directly influenced the flexible description of geometrical parameters and electronic populations. Deuterated water and ammonia were used to estimate the intermolecular interaction energies and hydrogen bond structures. The interaction energies of deuterated complexes were smaller than those of protonated ones, because the hydrogen bond distances in the deuterated complexes were longer than those in their protonated analogs. We also analyzed the stability afforded by formation of cyclic trimer structures and induced by the hydrogen/deuterium isotope effect. Through the replacement of protons with deuterons, the difference in quantum effects between protons and deuterons was reflected in the interaction energies and hydrogen bond structures

263

An Intermolecular Vibration Model for Lattice Ice  

Directory of Open Access Journals (Sweden)

Full Text Available Lattice ice with tetrahedral arrangement is studied using a modified Einstein’s model that incorporates the hindered translational and rotational vibration bands into a harmonic oscillation system. The fundamental frequencies for hindered translational and rotational vibrations are assigned based on the intermolecular vibration bands as well as thermodynamic properties from existing experimental data. Analytical forms for thermodynamic properties are available for the modified model, with three hindered translational bands at (65, 229, 229 cm-1 and three effective hindered rotational bands at 560 cm-1. The derived results are good for temperatures higher than 30 K. To improve the model below 30 K, Lorentzian broadening correction is added. This simple model helps unveil the physical picture of ice lattice vibration behavior.

Quinn M. Brewster

2010-06-01

264

Some mathematical models of intermolecular autophosphorylation.  

Science.gov (United States)

Intermolecular autophosphorylation refers to the process whereby a molecule of an enzyme phosphorylates another molecule of the same enzyme. The enzyme thereby catalyses its own phosphorylation. In the present paper, we develop two generic models of intermolecular autophosphorylation that also include dephosphorylation by a phosphatase of constant concentration. The first of these, a solely time-dependent model, is written as one ordinary differential equation that relies upon mass-action and Michaelis-Menten kinetics. Beginning with the enzyme in its dephosphorylated state, it predicts a lag before the enzyme becomes significantly phosphorylated, for suitable parameter values. It also predicts that there exists a threshold concentration for the phosphorylation of enzyme and that for suitable parameter values, a continuous or discontinuous switch in the phosphorylation of enzyme are possible. The model developed here has the advantage that it is relatively easy to analyse compared with most existing models for autophosphorylation and can qualitatively describe many different systems. We also extend our time-dependent model of autophosphorylation to include a spatial dependence, as well as localised binding reactions. This spatio-temporal model consists of a system of partial differential equations that describe a soluble autophosphorylating enzyme in a spherical geometry. We use the spatio-temporal model to describe the phosphorylation of an enzyme throughout the cell due to an increase in local concentration by binding. Using physically realistic values for model parameters, our results provide a proof-of-concept of the process of activation by local concentration and suggest that, in the presence of a phosphatase, this activation can be irreversible. PMID:25636493

Doherty, Kevin; Meere, Martin; Piiroinen, Petri T

2015-04-01

265

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

266

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

267

Investigations of the intermolecular forces between RDX and polyethylene by force-distance spectroscopy and molecular dynamics simulations.  

Science.gov (United States)

The development of novel nanoenergetic materials with enhanced bulk properties requires an understanding of the intermolecular interactions occurring between molecular components. We investigate the surface interactions between 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and polyethylene (PE) crystals on the basis of combined use of molecular dynamics (MD) simulations and force-distance spectroscopy, in conjunction with Lifshitz macroscopic theory of van der Waals forces between continuous materials. The binding energy in the RDX-PE system depends both on the degree of PE crystallinity and on the RDX crystal face. Our MD simulations yield binding energies of approximately 132 and 120 mJ/m(2) for 100% amorphous and 100% crystalline PE on RDX (210), respectively. The average value is about 36% greater than our experimental value of 81 ± 15 mJ/m(2) for PE (?48% amorphous) on RDX (210). By comparison, Liftshitz theory predicts a value of about 79 mJ/m(2) for PE interacting with RDX. Our MD simulations also predict larger binding energies for both amorphous and crystalline PE on RDX (210) compared to the RDX (001) surface. Analysis of the interaction potential indicates that about 60% of the binding energy in the PE-RDX system is due to attractive interactions between HPE-ORDX and CPE-NRDX pairs of atoms. Further, amorphous PE shows a much longer interaction distance than crystalline PE with the (210) and (001) RDX surfaces due to the possibility of larger polymer elongations in the case of amorphous PE as strain is applied. Also, we report estimates of the binding energies of energetic materials RDX and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) with PE, propylene, polystyrene, and several fluorine-containing polymers using Lifshitz theory and compare these with reported MD calculations. PMID:24922563

Taylor, D E; Strawhecker, K E; Shanholtz, E R; Sorescu, D C; Sausa, R C

2014-07-10

268

Intermolecular potential functions from spectroscopic properties of weakly bound complexes. Third progress report, July 1, 1991--June 30, 1992  

Energy Technology Data Exchange (ETDEWEB)

Goal is to consolidate the information from high resolution spectroscopy of weakly bound cluster molecules through a theoretical model of intermolecular potential energy surfaces. The ability to construct analytic intermolecular potential functions that accurately predict the interaction energy between small molecules will have a major impact in chemistry, biochemistry, and biology. This document presents the evolution and capabilities of a potential function model developed here, and then describes plans for future developments and applications. This potential energy surface (PES) model was first used on (HCCH){sub 2}, (CO{sub 2}){sub 2}, HCCH - CO{sub 2}; it had to be modified to work with HX dimers and CO{sub 2}-HX complexes. Potential functions have been calculated for 15 different molecular complexes containing 7 different monomer molecules. Current questions, logical extensions and new applications of the model are discussed. The questions are those raised by changing the repulsion and dispersion terms. A major extension of the PES model will be the inclusion of induction effects. Projects in progress include PES calculations on (HCCH){sub 3}, CO{sub 2} containing complexes, (HX){sub 2}, HX - CO{sub 2}, CO{sub 2} - CO, (CO{sub 2}){sub 3}, and (OCS){sub 2}. The first PES calculation for a nonlinear molecule will be for water and ammonia complexes. Possible long-term applications for biological molecules are discussed. Differences between computer programs used for molecular mechanics and dynamics in biological systems are discussed, as is the problem of errors. 12 figs, 74 refs. (DLC)

Muenter, J.S.

1992-08-01

269

Low-energy electron interactions with biomolecules  

Science.gov (United States)

Low-energy electron interactions with biomolecules have been the focus of sustained attention over the past decade. The demonstration by Sanche and coworkers that even subexcitation and subionization electrons can induce strand breaks in DNA opened a new frontier in understanding radiation damage to living systems. Many studies of DNA subunits and their analogues, both experimental and theoretical, have elucidated likely mechanisms by which slow electrons attach to and disrupt DNA, although the full picture is far from clear and some elements of it remain controversial. Increasing attention is also being given to low-energy electron collisions with amino acids in order to explore possible mechanisms of electron-mediated radiation damage to proteins. In a completely different context, electron-biomolecule collisions are fundamental to spark ignition and cumbustion of biofuels such as methanol and ethanol. Not to be overlooked, either, is the simplest but most ubiquitous biomolecule of all, water, whose low-energy electron cross sections remain surprisingly ill-characterized. This talk will survery recent ab initio computational studies using the Schwinger multichannel method of DNA- and protein-related molecules, alcohols, and water. Much of the work to be presented was carried out in collaboration with experimentalists who undertook complementary measurements, allowing for useful comparisons to be made. Although the primary focus will be on electronically elastic collisions relevant to dissociative attachment and electron transport, electron-impact excitation cross sections for water will be presented and discussed.

Winstead, Carl

2012-06-01

270

Benzoyl transfer reactivities of racemic 2,4-di-O-acyl-myo-inosityl 1,3,5-orthoesters in the solid state: molecular packing and intermolecular interactions correlate with the ease of the reaction.  

Science.gov (United States)

Racemic 2,4-di-O-acyl-myo-inosityl 1,3,5-orthoesters undergo transesterification catalyzed by sodium carbonate with varying ease of reaction in the solid state; reactions in solution and melt do not show such varied differences. An interesting crystal of a 1:1 molecular complex of highly reactive racemic 2,4-di-O-benzoyl-myo-inosityl 1,3,5-orthoformate and its orthoacetate analogue exhibited better reactivity than the latter component alone. Single-crystal X-ray structures of the reactants have been correlated with the observed differences in the acyl-transfer efficiencies in the solid state. Although each of the derivatives helically self-assembles around the crystallographic 2(1) axis linked through O-H...O hydrogen bonding, the pre-organization of the reactive groups (C=O [El] and OH [Nu]), C-H...O and the C-H...pi interactions are significantly more favourable for the reactive derivatives than the less reactive ones. Bond-length distributions also showed differences; the O-C bond of the axial benzoyl group, which gets cleaved during the reaction, is longer (1.345-1.361 A) relative to the chemically equivalent O-C bond of the equatorial benzoyl group (1.316-1.344 A) in the reactive derivatives. These bond-length differences are not significant in the less reactive derivatives. The overall molecular organization is different too; the strikingly discrete helices, which may be viewed as "reaction tunnels" and are held by interhelical interactions, are clearly evident in the reactive derivatives in comparison with the less reactive ones. PMID:15714536

Sarmah, Manash P; Gonnade, Rajesh G; Shashidhar, Mysore S; Bhadbhade, Mohan M

2005-03-18

271

Intermolecular interaction potentials for the Ar–C2H2, Kr–C2H2, and Xe–C2H2 weakly bound complexes: Information from molecular beam scattering, pressure broadening coefficients, and rovibrational spectroscopy  

OpenAIRE

Integral cross sections and pressure broadening coefficients have been measured for the acetylene-krypton complex, by molecular beam scattering and by high resolution IR spectroscopy, respectively. A new potential energy surface (PES) is proposed to describe structure and dynamical properties of this prototypical weakly bound complex. The PES has been parametrized exploiting a novel atom-bond pairwise additive scheme and has been fitted to the experimental data. A similar PES has been obtaine...

Cappelletti, David; Bartolomei, Massimiliano; Carmona-novillo, Estela; Pirani, Fernando

2007-01-01

272

Gribov's inelastic screening in high energy nucleus–nucleus interaction  

International Nuclear Information System (INIS)

We show that at LHC energies an accounting for the Gribov's screenings in the framework of the quasi-eikonal approach generalized for nucleus–nucleus interactions leads to a significant (?19%) decrease in the number of participating nucleons and intra-nuclear collision multiplicity for Pb+Pb interactions. Predictions for other energies and interactions are given also

273

Quantum chemical study of ?-? stacking interactions of the bacteriochlorophyll dimer in the photosynthetic reaction center of Rhodobacter sphaeroides  

Science.gov (United States)

Intermolecular ?-? stacking interactions of the bacteriochlorophyll dimer in the photosynthetic reaction center of the purple bacterium Rhodobacter sphaeroides were analyzed by the second order Møller-Plesset perturbation method using the modified 6-31G*(0.25) basis set with diffuse d-polarization by Hobza and co-workers. MP2/6-31G*(0.25) calculations yield an intermolecular interaction energy of -21.50 kcal/mol for the bacteriochlorophyll dimer. Thus, the attractive nature of the ?-? stacking interaction of the bacteriochlorophyll dimer in the photosynthetic reaction center from Rhodobacter sphaeroides is, for the first time, firmly established.

Wang, Yanli; Hu, Xiche

2002-07-01

274

Intermolecularly-induced conformational disorder in ferrocene, 1-bromoferrocene and 1,1?-dibromoferrocene  

Science.gov (United States)

Conformational preferences for isolated molecules of ferrocene, 1-bromoferrocene and 1,1?-dibromoferrocene were obtained by combined use of matrix-isolation infrared spectroscopy and quantum chemical calculations. Monomeric ferrocene and 1-dibromoferrocene were found to exist in a low temperature argon matrix (T = 15 K) exclusively in the eclipsed configuration, which corresponds to their most stable conformation in gas phase. On the other hand, for the neat compounds in crystalline phase, intermolecular interactions induce conformational disorder, leading to presence in the room temperature polymorphic forms of monomeric units with the staggered (or nearly staggered) conformation. 1,1?-Dibromoferrocene exists in both gas phase and low temperature argon matrix in two conformers of C2 symmetry (C2-I and C2-II), with eclipsed cyclopentadienyl moieties and Br atoms opposed to H atoms. The populations of the two conformers trapped in the as-deposited matrix were found to correspond to those estimated from theory for the room temperature equilibrium gas phase. By increasing the temperature of the matrix (up to 35 K), the gas phase lower energy form (C2-I) converted to the C2-II form. Besides allowing the precise structural and spectroscopic characterization of the two forms, these studies also revealed that the C2-II conformer (having a largest dipole moment) is stabilized in the matrix media, thus becoming more stable than the C2-I form under these conditions. Very interestingly, the room temperature stable polymorph of the compound (Tfus = 325.4 ± 0.1 K) is composed by 1,1?-dibromoferrocene units exhibiting the C2v symmetry eclipsed conformation with opposed bromine atoms, which for the isolated molecule corresponds to the highest energy conformation along the ring torsional coordinate and is the transition state structure between the two symmetry equivalent C2-II minima. Differential scanning calorimetry, polarized light thermomicroscopy and infrared measurements on 1,1?-dibromoferrocene allowed to identify a new polymorph of the compound, with Tfus = 320.2 ± 0.1 K. On the whole, the results presented in this article represent illuminating examples of intermolecularly-induced conformational disorder in solid phase and of its relevance to polymorphism.

Silva, Patrícia A.; Maria, Teresa M. R.; Nunes, Cláudio M.; Eusébio, Maria Ermelinda S.; Fausto, Rui

2014-12-01

275

Current constraints on interacting holographic dark energy  

International Nuclear Information System (INIS)

Although there is mounting observational evidence that the cosmic expansion is undergoing a late-time acceleration, the physical mechanism behind such a phenomenon is yet unknown. In this Letter, we investigate a holographic dark energy (HDE) model with interaction between the components of the dark sector in the light of current cosmological observations. We use both the new gold sample of 182 type Ia supernovae (SNe Ia) and the 192 SNe Ia ESSENCE data, the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey and the shift parameter from the three-year Wilkinson Microwave Anisotropy Probe data. In agreement with previous results, we show that these observations suggest a very weak coupling or even a noninteracting HDE. The phantom crossing behavior in the context of these scenarios is also briefly discussed

276

Binding energies of hypernuclei and ?-nuclear interactions  

Science.gov (United States)

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

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

1986-03-01

277

Binding energies of hypernuclei and ?-nuclear interactions  

International Nuclear Information System (INIS)

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

278

Binding energies of hypernuclei and ?-nuclear interactions  

International Nuclear Information System (INIS)

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

279

Comparison of the local binding motifs in the imidazolium-based ionic liquids [EMIM][BF4] and [EMMIM][BF4] through cryogenic ion vibrational predissociation spectroscopy: Unraveling the roles of anharmonicity and intermolecular interactions  

Science.gov (United States)

We clarify the role of the critical imidazolium C(2)H position (the central C between N atoms in the heterocycle) in the assembly motif of the [EMIM][BF4] ionic liquid by analyzing the vibrational spectra of the bare EMIM+ ion as well as that of the cationic [EMIM]2[BF4]+ (EMIM+ = 1-ethyl-3-methylimidazolium, C6H11N2+) cluster. Vibrational spectra of the cold, mass-selected ions are obtained using cryogenic ion vibrational predissociation of weakly bound D2 molecules formed in a 10 K ion trap. The C(2)H behavior is isolated by following the evolution of key vibrational features when the C(2) hydrogen, the proposed binding location of the anion to the imidazolium ring, is replaced by either deuterium or a methyl group (i.e., in the EMMIM+ analogue). Strong features in the ring CH stretching region of the bare ion are traced to Fermi resonances with overtones of lower frequency modes. Upon incorporation into the EMIM+ ? ? ? BF4- ? ? ? EMIM+ ternary complex, the C(2)H oscillator strength is dramatically increased, accounting for the much more complicated patterns derived from the EMIM+ ring CH stretches in the light isotopomer, which are strongly suppressed in the deuterated analogue. Further changes in the spectra that occur when the C(2)H is replaced by a methyl group are consistent with BF4- attachment directly to the imidazolium ring in an arrangement that maximizes the electrostatic interaction between the molecular ions.

Fournier, Joseph A.; Wolke, Conrad T.; Johnson, Christopher J.; McCoy, Anne B.; Johnson, Mark A.

2015-02-01

280

Can B tbnd B triple bond be as potential proton acceptor: An ab initio study on unusual intermolecular T-shaped X-H···? interactions between OCB tbnd BCO and HF, HCl, HCN or H 2C 2  

Science.gov (United States)

The unusual T-shaped X-H···? hydrogen bonds are found between the B tbnd B triple bond and the acid hydrogen of HF, HCl, HCN and H 2C 2 using abinitio method at 6-311++G(2d,p) and aug-cc-pVTZ levels, accompanied by the B tbnd B bond contraction. The binding energies follow the order of OCB tbnd BCO···HF > OCB tbnd BCO···HCl > OCB tbnd BCO···HCN > OCB tbnd BCO···H 2C 2. The analyses of the charge density and electron density shifts explain the origin of the B tbnd B bond contraction and confirm that the B tbnd B triple bond can be as potential proton acceptor.

Ren, Fu-de; Cao, Duan-lin; Wang, Wen-liang; Wang, Jian-long; Li, Yong-xiang; Hu, Zhi-yong; Chen, Shu-sen

2008-03-01

281

Calculations on Noncovalent Interactions and Databases of Benchmark Interaction Energies.  

Czech Academy of Sciences Publication Activity Database

Ro?. 45, ?. 4 (2012), s. 663-672. ISSN 0001-4842 R&D Projects: GA ?R GBP208/12/G016 Grant ostatní: European Social Fund(XE) CZ.1.05/2.1.00/03.0058 Institutional research plan: CEZ:AV0Z40550506 Keywords : non-covalent interactions * covalent interactions * quantum chemical approach Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 20.833, year: 2012

Hobza, Pavel

2012-01-01

282

Mechanism of Intermolecular Electron Transfer in Bionanostructures  

Science.gov (United States)

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. Most patients are inoperable and hepatoma cells are resistant to conventional chemotherapies. Thus, the development of novel therapies for HCC treatment is of paramount importance. Amongst different alimentary factors, vitamin C and vitamin K3 In the present work, it has been shown that the treatment of mouse hepatoma MH-22A cells by vitamin C and vitamin K3 at the ratio of 100:1 greatly enhanced their cytotoxicity. When cells were subjected to vitamin C at 200 ?M or to vitamin K3 at 2 ?M separately, their viability reduced by only about 10%. However, when vitamins C and K3 were combined at the same concentrations, they killed more than 90% of cells. To elucidate the mechanism of the synergistic cytotoxicity of the C&K3 mixture, theoretical quantum-chemical analysis of the dynamics of intermolecular electron transfer (IET) processes within the complexes containing C (five forms) and K3 (one form) has been carried out. Optimization of the ground state complex geometry has been provided by means of GAUSSIAN03 package. Simulation of the IET has been carried out using NUVOLA package, in the framework of molecular orbitals (MO). The rate of IET has been calculated using Fermi Golden rule. The results of simulations allow us to create the preliminary model of the reaction pathway.

Gruodis, A.; Galikova, N.; Šarka, K.; Saul?, R.; Batiuškait?, D.; Saulis, G.

283

Molecular Interactions and Hydrogen Bond Tunneling Dynamics: Some New Perspectives  

Science.gov (United States)

The recent development of tunable far-infrared lasers and other high-resolution spectroscopic probes of weakly bound clusters is having a significant impact on our understanding of intermolecular forces and on the complex quantum tunneling dynamics that occur in hydrogen-bonded systems. Far-infrared studies of a variety of interactions are discussed, including several prototypical water-hydrophobe complexes, the water trimer, and the ammonia dimer. Particular attention is paid to the inversion of spectroscopic data to yield detailed intermolecular potential energy surfaces. Investigations of nonpairwise additivity are also described.

Saykally, Richard J.; Blake, Geoffrey A.

1993-03-01

284

Scattering with absorptive interaction: Energy-dependent potentials  

International Nuclear Information System (INIS)

The energy dependence and analytic structure of the effective interaction for elastic scattering of composite particles are investigated using Feshbach's projection technique. A generalized Levinson theorem is established for complex, nonlocal, and energy-dependent interactions. The analytical results are illustrated by means of Argand diagrams for a solvable model and the effect of energy-averaging is discussed

285

New models for intermolecular repulsion and their application to Van Der Waals complexes and crystals of organic molecules  

International Nuclear Information System (INIS)

Model intermolecular potentials are required for simulations of molecules in the gas, liquid, or solid phase. The widely used isotropic atom-atom model potentials are empirically fitted and based on the assumptions of transferability, combining rules and that atoms in molecules are spherical. This thesis develops a non-empirical method of modelling repulsion by applying the overlap model, which we show as a general non-empirical method of deriving repulsion potentials for a specific molecule. In this thesis, the repulsion parameters for an exponential atom-atom model potential are obtained from the ab initio charge density of a small organic molecule by making the assumption that the repulsion is proportional to the overlap of a pair of molecules. The proportionality constant is fixed by a limited number of intermolecular perturbation theory (IMPT) calculations. To complete the model potential, the electrostatic interaction is represented by a distributed multipole analysis, and the Slater-Kirkwood formula is used for the dispersion. These non-empirical potentials can reproduce experimental crystal structure when applied to crystal structure prediction of an oxyboryl derivative. A detailed study on further improving the overlap model was carried out for phenol-water, by including other minor intermolecular contributions of charge-transfer and penetration. High quality ab initio calculations on the complex were performed for use in comparison. To compare with experimene in comparison. To compare with experimental data, diffusion Monte Carlo simulations were performed with the potential, so that the effects of anharmonic zero-point motion on structure and energy of the system are included. When the system is too large for an IMPT calculation, the proportionality constant can be determined empirically by fitting the cell volume as shown in our study of crystal structures of chlorothalonil. This is used with an anisotropic repulsion model that has been derived for Cl and N atoms in chlorothalonil. This model potential reproduces the crystal structure well, and is used to predict other polymorphs by a search for minima in the lattice energy. (author)

286

The Growth of Structure in Interacting Dark Energy Models  

CERN Document Server

If dark energy interacts with dark matter, there is a change in the background evolution of the universe, since the dark matter density no longer evolves as a^{-3}. In addition, the non-gravitational interaction affects the growth of structure. In principle, these changes allow us to detect and constrain an interaction in the dark sector. Here we investigate the growth factor and the weak lensing signal for a class of interacting dark energy models. In these models, the interaction is determined by a linear combination of the dark sector densities, with constant energy transfer rates. Assuming a normalization to today's values of dark matter density and overdensity, the signal of the interaction is an enhancement (suppression) of both the growth factor and the lensing power, when the energy transfer in the background is from dark matter to dark energy (dark energy to dark matter).

Caldera-Cabral, Gabriela; Schaefer, Bjoern Malte

2009-01-01

287

Probing acid-amide intermolecular hydrogen bonding by NMR spectroscopy and DFT calculations  

Science.gov (United States)

Benzene carboxylic acids and benzamide act as their self-complement in molecular recognition to form inter-molecular hydrogen bonded dimers between amide and carboxylic acid groups, which have been investigated by 1H, 13C and 15N NMR spectroscopy. Extensive NMR studies using diffusion ordered spectroscopy (DOSY), variable temperature 1D, 2D NMR, established the formation of heterodimers of benzamide with benzoic acid, salicylic acid and phenyl acetic acid in deuterated chloroform solution. Association constants for the complex formation in the solution state have been determined. The results are ascertained by X-ray diffraction in the solid state. Intermolecular interactions in solution and in solid state were found to be similar. The structural parameters obtained by X-ray diffraction studies are compared with those obtained by DFT calculations.

Chaudhari, Sachin Rama; Suryaprakash, N.

2012-05-01

288

Optical evidence for intermolecular coupling in mixed films of pentacene and perfluoropentacene  

Science.gov (United States)

We present optical absorption spectra of mixed films of pentacene (PEN) and perfluoropentacene (PFP) grown on SiO2. We investigated the influence of intermolecular coupling between PEN and PFP on the optical spectra by analyzing samples with five different mixing ratios of PFP:PEN with variable angle spectroscopic ellipsometry and differential reflectance spectroscopy. The data show how the spectral shape is influenced by changes in the volume ratio of the two components. By comparison with the pure film spectra an attempt is made to distinguish transitions due to intermolecular coupling between PEN and PFP from transitions caused by interactions of PEN (PFP) with other molecules of the same type. We observe a new transition at 1.6 eV which is not found in the pure film spectra and which we assign to the coupling of PFP and PEN.

Broch, K.; Heinemeyer, U.; Hinderhofer, A.; Anger, F.; Scholz, R.; Gerlach, A.; Schreiber, F.

2011-06-01

289

Isoform-specific Intermolecular Disulfide Bond Formation of Heterochromatin Protein 1 (HP1)*  

Science.gov (United States)

Three mammalian isoforms of heterochromatin protein 1 (HP1), ?, ?, and ?, play diverse roles in gene regulation. Despite their structural similarity, the diverse functions of these isoforms imply that they are additionally regulated by post-translational modifications. Here, we have identified intermolecular disulfide bond formation of HP1 cysteines in an isoform-specific manner. Cysteine 133 in HP1? and cysteine 177 in HP1? were involved in intermolecular homodimerization. Although both HP1? and HP1? contain reactive cysteine residues, only HP1? readily and reversibly formed disulfide homodimers under oxidative conditions. Oxidatively dimerized HP1? strongly and transiently interacted with TIF1?, a universal transcriptional co-repressor. Under oxidative conditions, HP1? dimerized and held TIF1? in a chromatin component and inhibited its repression ability. Our results highlight a novel, isoform-specific role for HP1 as a sensor of the cellular redox state. PMID:20675861

Higo, Shuichiro; Asano, Yoshihiro; Kato, Hisakazu; Yamazaki, Satoru; Nakano, Atsushi; Tsukamoto, Osamu; Seguchi, Osamu; Asai, Mitsutoshi; Asakura, Masanori; Asanuma, Hiroshi; Sanada, Shoji; Minamino, Tetsuo; Komuro, Issei; Kitakaze, Masafumi; Takashima, Seiji

2010-01-01

290

Analytical and Numerical Calculations of Diffusion Effects on the Intermolecular Multiple Quantum Coherences in Solution NMR  

International Nuclear Information System (INIS)

We calculated the analytical solutions to evaluate the effects of diffusion on the iMQCs in CRAZED pulse sequences. The obtained solution has been verified using the results of numerical simulation. The diffusional behaviors of the iMQCs during both the evolution and detection time periods could be examined by the analytical solution, which was quite different from those of the conventional NMR experiments. Understanding the difference in diffusional behaviors could lead to useful applications such as diffusion MRI based on the detection of iMQCs. The intermolecular multiple quantum coherences (iMQCs) that are generated by intermolecular dipolar interactions between distant spins on different molecules, have recently gained considerable attention because their properties are intrinsically different from those of conventional single quantum coherences (SQCs) in solution NMR. This feature allows for a wider range of applications in NMR and MR imaging

291

Long-range intermolecular dispersion forces and circular dichroism spectra from first-principles calculations  

OpenAIRE

This work presents first-principles calculations of long-range intermolecular dispersion energies between two atoms or molecules and of electronic circular dichroism spectra of chiral molecules. The former is expressed in terms of the C6 dipole-dipole dispersion coefficients ??, and the latter is given in terms of the extinction coefficient. In a series of publications, the complex linear polarization propagator method has been shown to be a powerful tool to provide accurate ab initio and f...

Jiemchooroj, Auayporn

2007-01-01

292

Virtual photon interactions in high energy QCD  

International Nuclear Information System (INIS)

We study the interactions of virtual photons in the high energy limit of quantum chromodynamics (QCD). The subject is discussed in terms of two closely linked applications: the calculation of the total cross section for ?*?*-scattering and the description of DIS in the colour dipole model. We calculate virtual corrections in ?s to the process ?* q ? (qq)q and the tree level process ?* q ? (qqg)q in the high energy limit. From this calculation we obtain one-loop corrections to the effective ?*-reggeon-qq-vertex in the helicity basis of the virtual photon and the qq-pair. The loop integrals for the virtual corrections have been performed and expressed in dimensional regularization in terms of logarithms and dilogarithms. We have convoluted the virtual one-loop matrix elements with tree level matrix elements and expressed the integrals over the phase space of the qq-pair explicitly in terms of a set of standard integrals. The real corrections have been calculated and, in case of the longitudinal polarization, expressed in factorized form. From these calculations, the impact factor of virtual photons will be determined, allowing for a first prediction of the total cross section for ?*?*-scattering in the next-to-leading-log s approximation. The calculations in this thesis extend the photon wave function picture in the colour dipole model to next-to-leading order. For this pt-to-leading order. For this purpose, the real corrections with a qqg final state are analyzed in transverse configuration space and interpreted as a first higher Fock component of the photon wave function. In addition, the matrix elements that have been calculated in this thesis are needed for the calculation of jet cross sections. (orig.)

293

Strong and Electromagnetic Interactions at SPS Energies  

CERN Document Server

Particle production in peripheral Pb+Pb collisions has been measured at a beam energy of 158 GeV per nucleon, corresponding to psNN 17.3 GeV. The measurements provide full double differential coverage in a wide range of longitudinal and transverse momenta, including the central (“mid-rapidity”) area and extending far into the projectile fragmentation region. The resulting analysis shows the heavy ion reaction as a mixture of different processes. In particular, surprising phenomena, like the presence of large and strongly varying structures in the shape of the double differential cross section d2s /dxFd pT , are induced by the final state electromagnetic interaction between produced particles and the charged spectator system. This effect is largest at low transverse momenta, where it results in a deep valley in the xF -dependence of the produced p+/p? ratio. The basic characteristics of the electromagnetic phenomenon described above agree with the results of a theoretical analysis, performed by means of ...

Ribicki, Andrzej

2009-01-01

294

Pigment spectra and intermolecular interaction potentials in glasses and proteins.  

Science.gov (United States)

A model is proposed for chromophore optical spectra in solids over a wide range of temperatures and pressures. Inhomogeneous band shapes and their pressure dependence, as well as baric shift coefficients of spectral lines, selected by the frequency, were derived using Lennard-Jones potentials of the ground and excited states. Quadratic electron-phonon coupling constants, describing the thermal shift and broadening of zero-phonon lines, were also calculated. Experimentally, thermal shift and broadening of spectral holes were studied between 5 and 40 K for a synthetic pigment, chlorin, embedded in polymer hosts. The baric effects on holes were determined by applying hydrostatic He gas pressure up to 200 bar, at 6 K. Absorption spectra of pheophytin a, chlorophyll a, and beta-carotene in polymers and plant photosystem II CP47 complex were measured between 5 (or 77) and 300 K, and subject to Voigtian deconvolution. A narrowing of inhomogeneous bandwidth with increasing temperature, predicted on the basis of hole behavior, was observed as the shrinking of Gaussian spectral component. The Lorentzian broadening was ascribed to optical dephasing up to 300 K in transitions with weak to moderate linear electron-phonon coupling strength. The thermal broadening is purely Gaussian in multiphonon transitions (S(2) band of beta-carotene, Soret bands of tetrapyrrolic pigments), and the Lorentz process appears to be suppressed, indicating a lack of exponential dephasing. Density, polarity, polarizability, compressibility, and other local parameters of the pigment binding sites in biologically relevant systems can be deduced from spectroscopic data, provided that sufficient background information is available. PMID:17557783

Renge, I; van Grondelle, R; Dekker, J P

2007-10-01

295

Spherocity and thrust distributions in high energy neutrino interactions  

International Nuclear Information System (INIS)

A study of the hadronic system of charged current neutrino interactions in terms of the variables spherocity (S) and thrust (T) is presented. It is found that and for fixed hadronic energy are similar for neutrino interactions, e+e- annihilations and ?-Ne interactions. (Auth.)

296

Dark Mass Creation During EWPT Via Dark Energy Interaction  

CERN Document Server

We add Dark Matter Dark Energy terms with a quintessence field interacting with a Dark Matter field to a MSSM EW Lagrangian previously used to calculate the magnetic field created during the 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

2013-01-01

297

An analysis of two textbooks on the topic of intermolecular forces  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes the analysis of two commonly used high school (Grades 11 and 12 chemistry textbooks in Singapore to determine if the content presented in the topic of intermolecular forces is consistent with the concepts and propositional knowledge identified by the authors as essential for the learning and understanding of the topic according to the Singapore high school chemistry syllabus. The authors found that the two textbooks did not adequately discuss the electrostatic nature of intermolecular forces, and the factors influencing the polarity of bonds/molecules, hydrogen bonding and instantaneous dipole-induced dipole interactions. The insufficient coverage of the above areas may lead to students having alternative conceptions of intermolecular forces as they may have incomplete or little understanding of the concepts involved and relationships between these concepts. Thus, teachers need to analyse textbooks carefully before using the textbooks so that they can be more aware of the difficulties that students may face when reading the textbooks, and attend to these areas by careful elaboration and integration of concepts in their lessons.

Tan Kim Chwee, Daniel

2004-04-01

298

Early dark energy and its interaction with dark matter  

CERN Document Server

We study a class of early dark energy models which has substantial amount of dark energy in the early epoch of the universe. We examine the impact of the early dark energy fluctuations on the growth of structure and the CMB power spectrum in the linear approximation. Furthermore we investigate the influence of the interaction between the early dark energy and the dark matter and its effect on the structure growth and CMB. We finally constrain the early dark energy model parameters and the coupling between dark sectors by confronting to different observations and conclude that the early dark energy interacting with dark matter can contribute to alleviate the coincidence problem.

Pu, Bo-Yu; Wang, Bin; Abdalla, Elcio

2014-01-01

299

Protein-Protein Interaction Analysis by Docking  

OpenAIRE

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; Florian Fink; Wolfram Gronwald

2009-01-01

300

Vibrational Spectra of ??-Type BEDT-TTF Salts: Relationship between Conducting Property, Time-Averaged Site Charge and Inter-Molecular Distance  

Directory of Open Access Journals (Sweden)

Full Text Available The relationship between the conducting behavior and the degree of charge fluctuation in the ??-type BEDT-TTF salts is reviewed from the standpoints of vibrational spectroscopy and crystal structure. A group of ??-type ET salts demonstrates the best model compounds for achieving the above relationship because the two-dimensional structure is simple and great diversity in conducting behavior is realized under ambient pressure. After describing the requirement for the model compound, the methodology for analyzing the results of the vibrational spectra is presented. Vibrational spectroscopy provides the time-averaged molecular charge, the charge distribution in the two-dimensional layer, and the inter-molecular interactions, etc. The experimental results applied to 2/3-filled and 3/4-filled ??-type ET salts are reported. These experimental results suggest that the conducting property, the difference in the time-averaged molecular charges between the ionic and neutral-like sites, the alternation in the inter-molecular distances and the energy levels in the charge distributions are relevant to one another. The difference in the time-averaged molecular charges, ??, is a useful criterion for indicating conducting behavior. All superconductors presented in this review are characterized as small but finite ??.

Takashi Yamamoto

2012-07-01

301

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-I2-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-I2 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

302

SAMIE: statistical algorithm for modeling interaction energies.  

Science.gov (United States)

We are investigating the rules that govern protein-DNA interactions, using a statistical mechanics based formalism that is related to the Boltzmann Machine of the neural net literature. Our approach is data-driven, in which probabilistic algorithms are used to model protein-DNA interactions, given SELEX and/or phage data as input. In the current report, we trained the network using SELEX data, under the "one-to-one" model of interactions (i.e. one amino acid contacts one base). The trained network was able to successfully identify the wild-type binding sites of EGR and MIG protein families. The predictions using our method are the same or better than that of methods existing in the literature. However our methodology offers the potential to capitalise in quantitative detail, as well as to be used to explore more general model of interactions, given availability of data. PMID:11262933

Benos, P V; Lapedes, A S; Fields, D S; Stormo, G D

2001-01-01

303

New Molecular Collisional Interaction Effect in Low-Energy Sputtering  

Science.gov (United States)

An unexpected pronounced enhancement is observed in sputtering yields per atom for N+2 compared to N+ from a polycrystalline gold target. This effect is seen when the kinetic energy per projectile atom is below 500 eV and increases as projectile energy decreases to near-threshold energies. Enhancements for O+2 over O+ begin at even lower kinetic energies below 100 eV per atom. This new molecular interaction effect may be explained qualitatively by invoking a simple energy transfer model which involves the vibrational frequency of the molecule and the collisional interaction time.

Yao, Y.; Hargitai, Z.; Albert, M.; Albridge, R. G.; Barnes, A. V.; Gilligan, J. M.; Pratt Ferguson, B.; Lüpke, G.; Gordon, V. D.; Tolk, N. H.; Tully, J. C.; Betz, G.; Husinsky, W.

1998-07-01

304

Cosmological evolution with interaction between dark energy and dark matter  

Science.gov (United States)

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 and dark matter, 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.

Bolotin, Yuri L.; Kostenko, Alexander; Lemets, Oleg A.; Yerokhin, Danylo A.

2015-12-01

305

Low-energy hadronic interactions beyond the current algebra approach  

International Nuclear Information System (INIS)

The new low-energy AP3-interaction, which is produced by convergent box-constituent-quark-loop diagrams, is obtained within chiral perturbation theory at the quark level (CHPT)q with linear realization of chiral U(3) x U(3) symmetry. Its contributions to processes of low-energy interactions of low-lying mesons are investigated. The new interaction goes beyond the framework of the low-energy current algebra approach and of the effective chiral Lagrangians with linear realization of chiral symmetry, constructed at the hadronic level. (author). 17 refs, 3 figs

306

Load Matching and Grid Interaction of Net Zero Energy Buildings  

DEFF Research Database (Denmark)

“Net Zero Energy Building” has become a prominent wording to describe the synergy of energy efficient building and renewable energy utilization to reach a balanced energy budget over a yearly cycle. Taking into account the energy exchange with a grid infrastructure overcomes the limitations of seasonal energy storage on-site. Even though the wording “Net Zero Energy Building” focuses on the annual energy balance, large differences may occur between solution sets in the amount of grid interaction needed to reach the goal. The paper reports on the analysis of example buildings concerning the load matching and grid interaction. Indices to describe both issues are proposed and foreseen as part of a harmonized definition framework. The work is part of subtask A of the IEA SHCP Task40/ECBCS Annex 52: “Towards Net Zero Energy Solar Buildings”.

Voss, Karsten; Sartori, Igor

2010-01-01

307

Extended supramolecular organization of ?-systems using yet unexplored simultaneous intra- and inter-molecular H-bonding motifs of 1,3-dihydroxy derivatives.  

Science.gov (United States)

Unique H-bonding motifs of 1,3-dihydroxyl derivatives involving simultaneous intra- and inter-molecular H-bonding results in extended organization of pendant chromophores with a spatial distance suitable for ?-? interaction. A preformed assembly with appended acceptor units exhibits host-guest interaction with specific donors by charge-transfer complex formation. PMID:25706052

Mondal, Tathagata; Basak, Dipankar; Al Ouahabi, Abdelaziz; Schmutz, Marc; Mésini, Philippe; Ghosh, Suhrit

2015-03-10

308

Anisotropic potential energy surfaces for atmospheric gas-unsaturated hydrocarbon molecule interactions from differential scattering experiments  

Science.gov (United States)

The total differential scattering cross sections of several atmospheric gas-unsaturated hydrocarbon molecule systems (He, Ne, Ar, H2, N2, CO, and NO with C2H2,/ C2H4,/ C3H4, and C4H2) were measured using bolometric detection in a crossed-molecular beam apparatus. The observed angular scattering distributions exhibit damped rainbow and diffraction oscillations, providing information on the intermolecular potential energy surface anisotropy of each system. Light reduced-mass systems containing He and H2 show fast diffraction oscillations, while heavy reduced-mass systems with Ar, N2, CO, and NO show predominately a single broad rainbow oscillation. The Ne- C2H2,/ C2H4, and C3H4 systems at high angular resolution show both rainbow and diffraction features. Anisotropic Lennard-Jones N-6 and Barker model potential energy surfaces were determined for each system by a 'best-fit' comparison between the experimental cross section and a theoretical cross section, calculated using infinite-order-sudden (IOS), JKWB, and Born approximations. Adjustment of potential parameters ? and R m, expanded in Legendre polynomial functions of the proper molecular rotational symmetry, allowed adequate fits to the experimental data. Barker model potentials provide better descriptions of the collision dynamics due to better estimates of the long-range interactions. In comparison, the Lennard-Jones potentials are consistently more anisotropic in the well region and more steeply repulsive at short-range. The damped diffraction oscillations were observed to be most sensitive to the potential size anisotropy and rather insensitive to the potential shape anisotropy. The relative size anisotropies for the various systems increase in agreement with the number of C-C bonds along the hydrocarbon's molecular symmetry axis. The damped rainbow oscillations were observed to be sensitive to the potential shape anisotropy and less sensitive to potential size anisotropy. He, Ne, and H2- hydrocarbon interactions are found to have isotropic well depths, while the Ar, N2, NO, and CO-hydrocarbon interactions are anisotropic. The Ar hydrocarbon systems prefer T-shaped structures. Interestingly, the acetylene- diatom systems have more stable linear configurations, while the ethylene-diatom and allene-diatom systems prefer T-shaped geometries. The IOS results need to be compared with more accurate close-coupled quantum scattering calculations to determine the contributions of rotational inelastic transitions.

Stevenson, Kip Patrick

1997-11-01

309

Coherent Rayleigh-Brillouin scattering: Influence of the intermolecular potential  

Science.gov (United States)

The spectrum of the coherent Rayleigh-Brillouin scattering (CRBS) of light by rarefied gas is obtained by solving the Boltzmann equation numerically using the fast spectral method. The influence of the intermolecular potential on the CRBS spectrum is investigated and the accuracy of the prevailing Tenti's s6 kinetic model is evaluated. Our numerical results show that i) the intermolecular potential has a great influence on CRBS spectrum when the Knudsen number is between 0.05 and 1 and ii) the Tenti's s6 kinetic model can only predict the line shape accurately for Maxwell gases at small Knudsen numbers.

Wu, Lei; White, Craig; Scanlon, Thomas J.; Reese, Jason M.; Zhang, Yonghao

2014-12-01

310

Neon--methane and argon--methane isotropic interaction potentials from total differential cross sections  

International Nuclear Information System (INIS)

Total differential cross sections have been measured at three collision energies each for Ne--CH4 and Ar--CH4 using the crossed molecular beams technique. The differential cross sections were used along with literature viscosity and second virial coefficient data to determine reliable isotropic interaction potentials. The Ne--CH4 potential has a well depth of 66 +- 4 K and an intermolecular separation of 3.68 +- 0.02 A at the minimum while the Ar--CH4 potential has a well depth of 170 +- 8 K and an intermolecular separation of 3.85 +- 0.04 A at the minimum

311

Photoinduced intermolecular electron transfer from aromatic amines to coumarin dyes in sodium dodecyl sulphate micellar solutions  

Science.gov (United States)

Photoinduced intermolecular electron transfer interaction between coumarin dyes and aromatic amines has been investigated in sodium dodecyl sulphate micellar solutions using steady-state and time-resolved fluorescence quenching measurements. Steady-state fluorescence quenching of the coumarin dyes by the amine quenchers always shows a positive deviation from linear Stern-Volmer relationship, which arises due to the localized high quencher concentrations at the micellar Stern layer. In time-resolved fluorescence measurements, the analysis of the fluorescence decays following a micellar quenching kinetics model assuming a unified quenching constant (kq') per quencher occupancy does not give satisfactory results, especially for the higher quencher concentrations used. The observed fluorescence decays are, however, seen to fit reasonably well following a bi-exponential analysis for all the quencher concentrations used. The average fluorescence lifetimes of the coumarin dyes in the micellar solution as estimated from the bi-exponential decay analysis are seen to undergo a systematic reduction with the effective mean quencher concentrations. The bimolecular quenching constants (kq) thus estimated are seen to be much smaller than those reported in the homogeneous solutions (e.g., in acetonitrile), indicating that the electron transfer in the micellar media is inherently inefficient. Correlation of the observed kq values in the micellar solutions with the free-energy changes (?G0) for electron transfer reactions show an inversion in the observed rates as predicted by Marcus' outer sphere electron transfer theory at exergonicities more that ˜0.65 eV. To the best of our knowledge this is the first report on the Marcus inverted region observed for the electron transfer reactions in micellar solution.

Kumbhakar, Manoj; Nath, Sukhendu; Pal, Haridas; Sapre, Avinash V.; Mukherjee, Tulsi

2003-07-01

312

Cosmological Evolution of Interacting Phantom Energy with Dark Matter  

OpenAIRE

We investigate the cosmological evolution of an interacting phantom energy model in which the phantom field has interaction with the dark matter. We discuss the existence and stability of scaling solutions for two types of specific interactions. One is motivated by the conformal transformation in string theory and the other is motivated by analogy with dissipation. In the former case, there exist no scaling solutions. In the latter case, there exist stable scaling solutions,...

Guo, Zong-kuan; Cai, Rong-gen; Zhang, Yuan-zhong

2004-01-01

313

Interacting holographic dark energy models: A general approach  

CERN Document Server

Dark energy models inspired by the cosmological holographic principle are studied in homogeneous isotropic spacetime with a general choice for the dark energy density $\\rho_d=3(\\alpha H^2+\\beta\\dot{H})$. Special choices of the parameters enable us to obtain three different holographic models, including the holographic Ricci dark energy(RDE) model. Effect of interaction between dark matter and dark energy on the dynamics of those models are investigated for different popular forms of interaction. It is found that crossing of phantom divide can be avoided in RDE models for $\\beta>0.5$ irrespective of the presence of interaction. A choice of $\\alpha=1$ and $\\beta=2/3$ leads to a varying $\\Lambda$-like model introducing an IR cutoff length $\\Lambda^{-1/2}$. It is concluded that among the popular choices an interaction of the form $Q\\propto H\\rho_m$ suits the best in avoiding the coincidence problem in this model.

Som, S

2014-01-01

314

A detector for high-energy neutrino interactions  

International Nuclear Information System (INIS)

The authors describe the design, construction and performance of a large mass detector used at CERN to study high-energy neutrino interactions in iron. This detector combines magnetic spectrometry and hadron calorimetry techniques. (Auth.)

315

?-? 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)

316

Antiproton--deuteron interaction at intermediate energies and Glauber theory  

International Nuclear Information System (INIS)

The p-bard interaction at moderate energies is described in Glauber's theory. Experimental data on the cross sections of the p-bard interaction are used to obtain the total and elastic cross sections for scattering of an antiproton by a free neutron

317

The growth of structure in interacting dark energy models  

International Nuclear Information System (INIS)

If dark energy interacts with dark matter, there is a change in the background evolution of the universe, since the dark matter density no longer evolves as a?3. In addition, the non-gravitational interaction affects the growth of structure. In principle, these changes allow us to detect and constrain an interaction in the dark sector. Here we investigate the growth factor and the weak lensing signal for a new class of interacting dark energy models. In these models, the interaction generalises the simple cases where one dark fluid decays into the other. In order to calculate the effect on structure formation, we perform a careful analysis of the perturbed interaction and its effect on peculiar velocities. Assuming a normalization to today's values of dark matter density and overdensity, the signal of the interaction is an enhancement (suppression) of both the growth factor and the lensing power, when the energy transfer in the background is from dark matter to dark energy (dark energy to dark matter)

318

Interacting agegraphic quintessence dark energy in non-flat universe  

International Nuclear Information System (INIS)

We establish a correspondence between interacting agegraphic dark energy model and the quintessence scalar field in a non-flat universe. We demonstrate that the agegraphic evolution of the universe can be described completely by a single quintessence scalar field. We also reconstruct the potential of the interacting agegraphic quintessence dark energy as well as the dynamics of the quintessence scalar field which describe the quintessence cosmology

319

Statefinder diagnosis and the interacting ghost model of dark energy  

OpenAIRE

A new model of dark energy namely "ghost dark energy model" has recently been suggested to interpret the positive acceleration of cosmic expansion. The energy density of ghost dark energy is proportional to the hubble parameter. In this paper we perform the statefinder diagnostic tool for this model both in flat and non-flat universe. We discuss the dependency of the evolutionary trajectories in $s-r$ and $q-r$ planes on the interaction parameter between dark matter and dark...

Malekjani, M.; Khodam-mohammadi, A.

2012-01-01

320

Intermolecular Casimir-Polder Forces in Water and near Surfaces  

CERN Document Server

The Casimir-Polder force is an important long range interaction involved in adsorption and desorption of molecules in fluids. We explore Casimir-Polder interactions between methane molecules in water, and between a molecule in water near SiO2 and hexane surfaces. Inclusion of the finite molecular size in the expression for the Casimir-Polder energy leads to estimates of the dispersion contribution to the binding energies between molecules and between one molecule and a planar surface.

Thiyam, Priyadarshini; Sernelius, Bo E; Parsons, Drew F; Malthe-Sørenssen, Anders; Boström, Mathias

2014-01-01

321

Curcumin amorphous solid dispersions: the influence of intra and intermolecular bonding on physical stability.  

Science.gov (United States)

We have investigated the physical stability of amorphous curcumin dispersions and the role of curcumin-polymer intermolecular interactions in delaying crystallization. Curcumin is an interesting model compound as it forms both intra and intermolecular hydrogen bonds in the crystal. A structurally diverse set of amorphous dispersion polymers was investigated; poly(vinylpyrrolidone), Eudragit E100, carboxymethyl cellulose acetate butyrate, hydroxypropyl methyl cellulose (HPMC) and HPMC-acetate succinate. Mid-infrared spectroscopy was used to determine and quantify the extent of curcumin-polymer interactions. Physical stability under different environmental conditions was monitored by powder X-ray diffraction. Curcumin chemical stability was monitored by UV-Vis spectroscopy. Isolation of stable amorphous curcumin was difficult in the absence of polymers. Polymers proved to be effective curcumin crystallization inhibitors enabling the production of amorphous solid dispersions; however, the polymers showed very different abilities to inhibit crystallization during long-term storage. Curcumin intramolecular hydrogen bonding reduced the extent of its hydrogen bonding with polymers; hence most polymers were not highly effective crystallization inhibitors. Overall, polymers proved to be crystallization inhibitors, but inhibition was limited due to the intramolecular hydrogen bonding in curcumin, which leads to a decrease in the ability of the polymers to interact at a molecular level. PMID:24192454

Wegiel, Lindsay A; Zhao, Yuhong; Mauer, Lisa J; Edgar, Kevin J; Taylor, Lynne S

2014-12-01

322

Interactions between renewable energy policy and renewable energy industrial policy: A critical analysis of China's policy approach to renewable energies  

International Nuclear Information System (INIS)

This paper analyzes China's policy approach to renewable energies and assesses how effectively China has met the ideal of appropriate interactions between renewable energy policy and renewable energy industrial policy. First we briefly discuss the interactions between these two policies. Then we outline China's key renewable energy and renewable industrial policies and find that China's government has well recognized the need for this policy interaction. After that, we study the achievements and problems in China's wind and solar PV sector during 2005–2012 and argue that China's policy approach to renewable energies has placed priority first on developing a renewable energy manufacturing industry and only second on renewable energy itself, and it has not effectively met the ideal of appropriate interactions between renewable energy policy and renewable energy industrial policy. Lastly, we make an in-depth analysis of the three ideas underlying this policy approach, that is, the green development idea, the low-carbon leadership idea and indigenous innovation idea. We conclude that Chinas' policy approach to renewable energies needs to enhance the interactions between renewable energy policy and renewable energy industrial policy. The paper contributes to a deeper understanding of China's policy strategy toward renewable energies. -- Highlights: •Interactions between renewable energy policy and renewable energy industrial policy are discussed. •China's key renewable energy and renewable energy industrial policies are outlined. •Two empirical cases illustrate China's policy approach to renewable energies. •We argue that China needs to enhance the interactions between the two policies. •Three ideas underlie China's policy approach to renewable energies

323

Coordinative peptide recognition. Making intermolecular processes intramolecular  

OpenAIRE

The design of synthetic receptors that function under physiological conditions is still a challenge. A successful strategy is the use of reversible coordination of Lewis-basic guest molecules to Lewis-acidic metal complexes to provide high and selective binding affinities in water. A screening experiment using potentiometric titration was used to find suitable metal complex ? side chain interactions. Imidazol showed affinities towards NTA and IDA complexes of Cu(II) and Ni(II). Zn(II) ...

Kruppa, Michael

2006-01-01

324

New energy performance indexes for energy-efficient interactive buildings  

OpenAIRE

This paper argues that promoting energy supply by Renewable Energy Sources (RES) in buildings, namely residential, requires additional informative indexes to be included in buildings Energy Performance Certificates. The load-generation approach for the energy balance is here discussed, and compared with the current recommended by CEN/TR 15615, i.e. the delivered-exported approach. Besides the Energy Performance Index, which takes the same value for both approaches, other indexes are studied. ...

Pana?o, Marta Oliveira; Camelo, Susana; Gonc?alves, Helder

2013-01-01

325

Comparative assessment of energy-economy interactions  

Energy Technology Data Exchange (ETDEWEB)

This analysis is concerned with the impact of energy-policy measures on the level, growth, and structure of the US economy. In particular, the nature and magnitude of the causal relationship between variations in the prices of various energy forms and economic performance, as measured by real gross national product (GNP), is studied. The combined Brookhaven National Laboratory/Dale W. Jorgenson Associates (BNL/DHA) energy-economy model system is used to determine the economic effects of three energy-price futures combined with an invariant set of energy policies. The price alternatives are intended to characterize the uncertainty that exists in the policy-planning environment. In addition, the results are compared to those obtained from another DOE-sponsored analysis which used the Data Resources, Incorporated (DRI) quarterly macroeconomic model to assess the effects of these same three cases. Significant numerical differences in the results from these modeling systems are observed and are attributed to structural differences between the two methodologies. The methodological issues emerging from this comparison have important policy implications which are independent of the specific numerical conclusions. Since it is uncertain which, if either, of the models is correct, the use of one for policy analysis entails the risk that policy will be predicated on inaccurate information. This risk is analyzed within an explicit framework and clear decision rules for information selection and the choice between the modeling systems are formulated.

Goettle, R.J. IV; Hudson, E.A.; Lukachinski, J.

1978-12-01

326

Characterization of photoinduced self-exchange reactions at molecule-semiconductor interfaces by transient polarization spectroscopy: lateral intermolecular energy and hole transfer across sensitized TiO2 thin films.  

Science.gov (United States)

Transient anisotropy measurements are reported as a new spectroscopic tool for mechanistic characterization of photoinduced charge-transfer and energy-transfer self-exchange reactions at molecule-semiconductor interfaces. An anisotropic molecular subpopulation was generated by photoselection of randomly oriented Ru(II)-polypyridyl compounds, anchored to mesoscopic nanocrystalline TiO(2) or ZrO(2) thin films, with linearly polarized light. Subsequent characterization of the photoinduced dichromism change by visible absorption and photoluminescence spectroscopies on the nano- to millisecond time scale enabled the direct comparison of competitive processes: excited-state decay vs self-exchange energy transfer, or interfacial charge recombination vs self-exchange hole transfer. Self-exchange energy transfer was found to be many orders-of-magnitude faster than hole transfer at the sensitized TiO(2) interfaces; for [Ru(dtb)(2)(dcb)](PF(6))(2), where dtb is 4,4'-(C(CH(3))(3))(2)-2,2'-bipyridine and dcb is 4,4'-(COOH)(2)-2,2'-bipyridine, anchored to TiO(2), the energy-transfer correlation time was ?(ent) = 3.3 ?s while the average hole-transfer correlation time was = 110 ms, under identical experimental conditions. Monte Carlo simulations successfully modeled the anisotropy decays associated with lateral energy transfer. These mesoscopic, nanocrystalline TiO(2) thin films developed for regenerative solar cells thus function as active "antennae", harvesting sunlight and transferring energy across their surface. For the dicationic sensitizer, [Ru(dtb)(2)(dcb)](PF(6))(2), anisotropy changes indicative of self-exchange hole transfer were observed only when ions were present in the acetonitrile solution. In contrast, evidence for lateral hole transfer was observed in neat acetonitrile for a neutral sensitizer, cis-Ru(dnb)(dcb)(NCS)(2), where dnb is 4,4'-(CH(3)(CH(2))(8))(2)-2,2'-bipyridine, anchored to TiO(2). The results indicate that mechanistic models of interfacial charge recombination between electrons in TiO(2) and oxidized sensitizers must take into account diffusion of the injected electron and the oxidized sensitizer. The phenomena presented herein represent two means of concentrating potential energy derived from visible light that could be used to funnel energy to molecular catalysts for multiple-charge-transfer reactions, such as the generation of solar fuels. PMID:21861499

Ardo, Shane; Meyer, Gerald J

2011-10-01

327

Low-energy Antiproton Neon Interaction  

OpenAIRE

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 K(0)(s) in the pbar Ne interaction were measured at 19.6, 48.7 and 179.6 MeV. Annihilation was found to be dominant over all other non-elastic pbar 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 pbar-n...

Ferrero, Livio; Busso, Luigi; Balestra, Ferruccio; Grasso, Antonino; Piragino, Guido; Bussa, Maria Pia; Panzieri, Daniele

1986-01-01

328

Intermediate-energy hadron interactions, II  

International Nuclear Information System (INIS)

The topics to be covered are as follows. I'll begin with new developments in NN ? NN? reactions. This will provide a natural lead-in to the main topic of this talk, which is dibaryons. This will be followed by discussion of elastic proton-deuteron and inelastic proton-alpha scattering. Then there will be a brief mention of two technical developments. Finally, I'll close by giving short remarks about two peculiarities that were found by theorists looking at strong interaction amplitudes. 15 refs., 3 figs

329

Effective Theory of Interacting Dark Energy  

CERN Document Server

We present a unifying treatment of dark energy and modified gravity that allows distinct conformal-disformal couplings of matter species to the gravitational sector. In this very general approach, we derive the conditions to avoid ghost and gradient instabilities. We compute the equations of motion for background quantities and linear perturbations. We illustrate our formalism with two simple scenarios, where either cold dark matter or a relativistic fluid is nonminimally coupled. This extends previous studies of coupled dark energy to a much broader spectrum of gravitational theories.

Gleyzes, Jérôme; Mancarella, Michele; Vernizzi, Filippo

2015-01-01

330

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

331

Intermolecular reaction screening as a tool for reaction evaluation.  

Science.gov (United States)

Synthetic organic chemistry underpins many scientific disciplines. The development of new synthetic methods proceeds with the ultimate intention of providing access to novel structural motifs or providing safer, increasingly efficient, or more economical chemical reactions. To facilitate the identification and application of new methods in solving real synthetic problems, this Account will highlight the benefits of providing a fuller picture of both the scope and limitations of new reactions, with a primary focus on the evaluation of functional group tolerance and stability of a reaction using intermolecular screens. This Account will begin with a discussion on reaction evaluation, specifically considering the suitability of a given reaction for application in target-oriented synthesis. A comparison of desirable and essential criteria when choosing a reaction is given, and a short discussion on the value of negative and qualitative data is provided. The concept of intermolecular reaction screening will be introduced, and a direct comparison with a traditional substrate scope highlights the benefits and limitations of each and thus the complementary nature of these approaches. In recent years, a number of ad hoc applications of intermolecular screens to evaluate the functional group tolerance of a reaction or the stability of functional groups to a given set of reaction conditions have been reported, and will be discussed. More recently, we have developed a formal high-throughput intermolecular screening protocol that can be utilized to rapidly evaluate new chemical reactions. This simple and rapid protocol enables a much broader evaluation of a reaction in terms of functional group tolerance and the stability of chemical motifs to the reaction conditions than is feasible with a typical reaction scope. The development, evaluation, and application of this method within our group will be discussed in detail, with both the potential benefits and limitations highlighted and discussed. In addition, we will discuss more recent applications of intermolecular screens from both industrial and academic groups. Modifications in protocols and applications will be highlighted, including problem based evaluations, assessment of biomolecule compatibility, establishment of relative rate data, and the identification of new reactivity. Such screens have been applied in diverse chemistries including C-H functionalization reactions, frustrated Lewis-pair-catalyzed hydrogenations, heterogeneous catalysis, photoredox catalysis, enantioselective organocatalysis, and polymer science. We feel that the application of intermolecular screens to such a diversity of reactions highlights the practical simplicity of such screens. A summary of the applications and potential utility of intermolecular reaction evaluation is provided. PMID:25699585

Collins, Karl D; Glorius, Frank

2015-03-17

332

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

333

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

334

Exact zero-point interaction energy between cylinders  

CERN Document Server

We calculate the exact Casimir interaction energy between two perfectly conducting, very long, eccentric cylindrical shells using a mode summation technique. Several limiting cases of the exact formula for the Casimir energy corresponding to this configuration are studied both analytically and numerically. These include concentric cylinders, cylinder-plane, and eccentric cylinders, for small and large separations between the surfaces. For small separations we recover the proximity approximation, while for large separations we find a weak logarithmic decay of the Casimir interaction energy, typical of cylindrical geometries.

Mazzitelli, F D; Lombardo, F C

2006-01-01

335

Observational constraints on the interacting Ricci dark energy model  

OpenAIRE

We consider an extension of the holographic Ricci dark energy model by introducing an interaction between dark energy and matter. In this model, the dark energy density is given by $rho_{Lambda}=-frac{1}{2}alpha M_{p}^{2}{R}$, where ${R}$ is the Ricci scalar curvature, $M_{p}$ is the reduced Planck mass, and $alpha$ is a dimensionless parameter. The interaction rate is given by $Q=gamma H rho_{Lambda}$, where $H$ is the Hubble expansion rate, and $gamma$ is a dimensionless p...

Suwa, Masashi; Nihei, Takeshi

2009-01-01

336

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.)

337

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

338

Photochemistry on surfaces. Intermolecular energy electron transfer processes between excited Ru(bpy){sub 3}{sup 2+} and H-aggregates of cresyl violet on SiO{sub 2} and SnO{sub 2} colloids  

Energy Technology Data Exchange (ETDEWEB)

Cresyl violet, a cationic dye (CV{sup +}), forms H-aggregates on the negatively charged SiO{sub 2} and SnO{sub 2} colloids. These aggregates exhibit broad absorbance around 520 nm. By coadsorbing a sensitizer, Ru(bpy){sub 3}{sup 2+}, we are able to characterize the triplet excited state and reduced form of dye-aggregates on the colloidal SiO{sub 2} and SnO{sub 2} suspensions. On SiO{sub 2} surfaces, the excited state quenching of Ru(bpy){sub 3}{sup 2+} by dye-aggregates proceeds via an energy transfer mechanism. Picosecond laser flash photolysis experiments indicate that such a surface-promoted energy transfer is completed within 20 ps. On the other hand dye-aggregates adsorbed onto SnO{sub 2} colloids undergo photosensitized reduction since the excited sensitizer, Ru(bpy){sub 3} {sup 2+}, is efficiently quenched by the semiconductor support. The role of support material in promoting energy and electron transfer processes is described. 87 refs., 11 figs.

Liu, D.; Hug, G.L.; Kamat, P.V. [Univ. of Notre Dame, IN (United States)

1995-11-09

339

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

340

Intermolecular potentials from nuclear spin lattice relaxation in pure gases with octahedral symmetry  

Science.gov (United States)

Fluorine spin lattice relaxation times per unit density T1/? in pure SF6, MoF6, WF6 and UF6 gases are experimentally found to be proportional to T-1·5 where T is the temperature. These data can be analysed to obtain information on the anisotropic part of the intermolecular potential in these systems. Hard sphere, Lennard-Jones (6-12) and modified Buckingham (exp-6) potentials were used for the isotropic part of the intermolecular interaction. The analysis is made using the Bloom-Oppenheim theory, assuming that the correlation time of the spin rotation interaction can be approximated by the average lifetime of a molecule in the given J state. We have obtained the strengths of the repulsive and attractive terms in the anisotropic potential. From the strength of the attractive term in the anisotropic potential, the hexadecapole moments of all the four molecules are obtained. The hexadecapole moment of SF6 obtained by us using the Lennard-Jones model is in good agreement with the values reported earlier, based on other techniques, while the values for MoF6, WF6 and UF6 are reported for the first time.

Ursu, I.; Bogdan, M.; Balibanu, F.; Fitori, P.; Mihailescu, G.; Demco, D. E.

341

Accuracy of Several Wave Function and Density Functional Theory Methods for Description of Noncovalent Interaction of Saturated and Unsaturated Hydrocarbon Dimers.  

Czech Academy of Sciences Publication Activity Database

Ro?. 8, ?. 7 (2012), s. 2282-2292. ISSN 1549-9618 Grant ostatní: APVV(SK) APVV-0059-10 Institutional research plan: CEZ:AV0Z40550506 Keywords : intermolecular interaction energies * Plesset perturbation-theory * molecular-orbital methods * protein rubredoxin Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.389, year: 2012

Granatier, Jaroslav; Pito?ák, M.; Hobza, Pavel

2012-01-01

342

Intermolecular forces and scaling relations between heterogeneous macromolecular surfaces  

Science.gov (United States)

Most theories regarding the behavior of intermolecular forces assume perfectly smooth surfaces with well-defined chemical and material properties. In this thesis, three separate systems are studied to explore the accuracy of this assumption in very different situations. In the first system, the effects of milli-molar amounts of dissolved gas (the amount typically present in normal atmospheric conditions) have been studied at a pristine oil/water interface. It was found that the removal of the dissolved gas significantly increased the lifetime of the oil droplets, effectively reducing the long-range hydrophobic attractive force present under standard conditions. In the second system, the effect of varying normal and lateral roughness of solid surfaces in understanding the long-range steric forces and shorter-range adhesive (van der Waals) forces are studied. Various techniques to reproducibly control and vary the roughness were developed for a number of different types of polymeric surfaces. A strong correlation between the roughness and the repulsive steric force was observed for randomly rough surfaces. Similar scaling relations between the roughness and the magnitude of the adhesive force were measured. Friction measurements between these surfaces show that even a few nanometers of roughness significantly reduces the critical shear stress required to initiate sliding. However, the coefficient of friction was relatively unaffected by the range of roughness considered, in agreement with the macroscopic Amontons' law. The third and final system dealt with the properties of adsorbed layers of polyampholytes (containing both positively and negatively charged groups), as opposed to the more common classes of neutral polymers or polyelectrolytes. These measurements took advantage of a naturally occurring family of proteins (a class of polyampholytes), known as tau, which exist in six different well-defined lengths and charge densities. Force measurements were made with a Surface Forces Apparatus (SFA) in various ionic solution conditions, combined with high resolution imaging by an Atomic Force Microscope (AFM). Scaling relations between the magnitude and range of the total interaction force are shown depending on the total length as well as the relative ratio of positive to negative groups along the backbone of the macromolecule.

Rosenberg, Kenneth J.

343

THz absorption spectrum of the CO2–H2O complex: Observation and assignment of intermolecular van der Waals vibrations  

DEFF Research Database (Denmark)

Terahertz absorption spectra have been recorded for the weakly bound CO2–H2O complex embedded in cryogenic neon matrices at 2.8 K. The three high-frequency van der Waals vibrational transitions associated with out-of-plane wagging, in-plane rocking, and torsional motion of the isotopic H2O subunit have been assigned and provide crucial observables for benchmark theoretical descriptions of this systems’ flat intermolecular potential energy surface. A (semi)-empirical value for the zero-point energy of 273 ± 15 cm?1 from the class of intermolecular van der Waals vibrations is proposed and the combination with high-level quantum chemical calculations provides a value of 726 ± 15 cm?1 for the dissociation energy D0

Andersen, Jonas; Heimdal, J.

2014-01-01

344

THz absorption spectrum of the CO2-H2O complex: Observation and assignment of intermolecular van der Waals vibrations  

DEFF Research Database (Denmark)

Terahertz absorption spectra have been recorded for the weakly bound CO2-H2O complex embedded in cryogenic neon matrices at 2.8 K. The three high-frequency van der Waals vibrational transitions associated with out-of-plane wagging, in-plane rocking, and torsional motion of the isotopic H2O subunit have been assigned and provide crucial observables for benchmark theoretical descriptions of this systems' flat intermolecular potential energy surface. A (semi)-empirical value for the zero-point energy of 273 ± 15 cm-1 from the class of intermolecular van der Waals vibrations is proposed and the combination with high-level quantum chemical calculations provides a value of 726 ± 15 cm-1 for the dissociation energy D0. © 2014 AIP Publishing LLC.

Andersen, Jonas; Heimdal, J.

2014-01-01

345

Binding energies of ?? hypernuclei and the ?? interaction  

Science.gov (United States)

The binding energies of the ?? hypernuclei 10??Be and 6??He are calculated variationally with a 2? + 2? and with an ? + 2? model, respectively. For 10??Be the integrations were made with Monte Carlo techniques while for 6??He direct numerical methods were used. A wide range of phenomenological ?? potentials based on meson-exchange models was considered. An approximately universal linear relation between the calculated values of B ??( 10??Be) and of B ??( 6??He) is obtained. For the experimental value of B ??( 10??Be) = 17.7 ± 0.1 MeV this relation predicts a much too small value of B ??( 6??He) , well below the lower limit of the quoted experimental value of 10.9 ± 0.6 MeV. For ?? potentials with repulsive cores the relations, for a given B ??( 10??Be) , between the low-energy ?? scattering parameters a, r0 and the intrinsic range b are both approximately universal and independent of the detailed potential shape. For the experimental value of B ??( 10??Be) the preferred values are 2.5 ? - a ? 3.5 fm, 2.6 ? r0 ? 3.1 fm. The large and negative values of a correspond to conditions not too far from a bound 1S 0 ?? state and could indicate a 6-quark dibaryon state with the same quantum numbers and above the ?? threshold.

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

1984-07-01

346

Binding energies of ?? hypernuclei and the ?? interaction  

International Nuclear Information System (INIS)

The binding energies of the ?? hypernuclei sub(??)10Be and sub(??)6He are calculated variationally with a 2? + 2? and with an ?+2? model, respectively. For sub(??)10Be the integrations were made with Monte Carlo technique while for sub(??)6He direct numerical methods were used. A wide range of phenomenological ?? potentials based on meson-exchange models was considered. An approximately universal linear relation between the calculated values of Bsub(??)(sub(??)10Be) and of Bsub(??)(sub(??)6He) is obtained. For the experimental value of Bsub(??)(sub(??)10Be)=17.7+-0.1 MeV this relation predicts a much too small value of Bsub(??)(sub(??)6He), well below the lower limit of the quoted experimental value of 10.9+-0.6 MeV. For ?? potentials with repulsive cores the relations, for a given Bsub(??)(sub(??)10Be), between the low-energy ?? scattering parameters a, r0 and the intrinsic range b are both approximately universal and independent of the detailed potential shape. For the experimental value of Bsub(??)(sub(??)10Be) the preferred values are 2.501S0 ?? state and could indicate a 6-quark dibaryon state with the same quantumbers and above the ?? threshold. (orig.)

347

Interatomic and intermolecular Coulombic decay: the coming of age story  

Science.gov (United States)

In pioneering work by Cederbaum et al an excitation mechanism was proposed that occurs only in loosely bound matter (Cederbaum et al 1997 Phys. Rev. Lett. 79 4778): it turned out, that (in particular) in cases where a local Auger decay is energetically forbidden, an excited atom or molecule is able to decay in a scheme which was termed ‘interatomic Coulombic decay’ (or ‘intermolecular Coulombic decay’) (ICD). As ICD occurs, the excitation energy is released by transferring it to an atomic or molecular neighbor of the initially excited particle. As a consequence the neighboring atom or molecule is ionized as it receives the energy. A few years later the existence of ICD was confirmed experimentally (Marburger et al 2003 Phys. Rev. Lett. 90 203401; Jahnke et al 2004 Phys. Rev. Lett. 93 163401; Öhrwall et al 2004 Phys. Rev. Lett. 93 173401) by different techniques. Since this time it has been found that ICD is not (as initially suspected) an exotic feature of van der Waals or hydrogen bonded systems, but that ICD is a very general and common feature occurring after a manifold of excitation schemes and in numerous weakly bound systems, as revealed by more than 200 publications. It was even demonstrated, that ICD can become more efficient than a local Auger decay in some system. This review will concentrate on recent experimental investigations on ICD. It will briefly introduce the phenomenon and give a short summary of the ‘early years’ of ICD (a detailed view on this episode of investigations can be found in the review article by U Hergenhahn with the same title (Hergenhahn 2011 J. Electron Spectrosc. Relat. Phenom. 184 78)). More recent articles will be presented that investigate the relevance of ICD in biological systems and possible radiation damage of such systems due to ICD. The occurrence of ICD and ICD-like processes after different excitation schemes and in different systems is covered in the middle section: in that context the helium dimer (He2) is a particularly interesting (and exotic) system in which ICD was detected. It was employed in several publications to elucidate the strong impact of nuclear motion on ICD and its longrange-character. The review will present these findings and their initial theoretical predictions and give insight into most recent time-resolved measurements of ICD.

Jahnke, T.

2015-04-01

348

The polarization approximation and the Amos-Musher intermolecular perturbation theories compared to infinite order at finite separations  

Science.gov (United States)

We argue that the most common form of intermolecular perturbation theory, the polarization approximation (PA), gives at finite separations, for nearly all systems, no usable, exact relationship between the lowest unperturbed energy and the physical ground state energy. This would be true even if the PA energy expansion converged. In contrast, the Amos-Musher (AM) theory does give an exact relationship between the lowest unperturbed energy and the physical ground state energy. We find no theoretical justification for using the PA theory beyond second order in the energy, but the AM theory may be extended to arbitrarily high order.

Adams, William H.

1994-11-01

349

On the importance and origin of aromatic interactions in chemistry and biodisciplines.  

Czech Academy of Sciences Publication Activity Database

Ro?. 46, ?. 4 (2013), s. 927-936. ISSN 0001-4842 R&D Projects: GA ?R GBP208/12/G016 Grant ostatní: Operational Program Research and Development for Innovations(XE) CZ.1.05/2.1.00/03.0058 Institutional support: RVO:61388963 Keywords : pi-pi interactions * potential-energy surface * ab-initio calculation * benzene dimer * intermolecular interaction * protein rubredoxin Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 24.348, year: 2013

Riley, Kevin Eugene; Hobza, Pavel

2013-01-01

350

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

351

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

352

Rototranslational collision-induced absorption and collision-induced light scattering spectra of molecular hydrogen using isotropic intermolecular potentials  

International Nuclear Information System (INIS)

Highlights: ? We have determined an isotropic intermolecular potential for the interaction of hydrogen. ? The thermophysical and transport properties are calculated for this system. ? The rovibrational energy levels and scattering cross-sections are determined. ? We have adopted a model for the induced dipole moment ?(r) with adjustable parameters. ? The quantum lineshapes of absorption and scattering are calculated. -- Abstract: Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures and of collision-induced light scattering (CILS) at room temperature are computed for gaseous molecular hydrogen using theoretical values for induced dipole moments and pair-polarizability trace and anisotropy as input. Comparison with measured spectra of absorption, isotropic and anisotropic light scattering shows satisfactory agreement, for which the uncertainty in measurement of its spectral moments is seen to be large. Empirical models of the dipole moment and pair-polarizability trace and anisotropy which reproduce the experimental spectra and the first three spectral moments more closely than the fundamental theory are also given. Good agreement between computed and experimental lineshapes of both absorption and scattering is obtained when potential models which are constructed from the thermophysical, transport, total scattering cross-section and spectroscopic properties are used. Also, the use of the new potential in lattice dynamic calculations yields good results for several properties of solid hydrogen.

353

Proton tunnelling in intermolecular hydrogen bonds  

International Nuclear Information System (INIS)

The wavefunctions of particles extend beyond the classically accessible regions of potential energy-surfaces (PES). A manifestation of this partial delocalization is the quantum-mechanical tunneling effect which enables a particle to escape from a metastable potential-well. Tunnelling is most important for the lightest atoms, so that the determination of its contribution to proton transfer, one of the most fundamental chemical reactions, is an important issue. QENS and NMR techniques have been employed to study the motion of protons in the hydrogen bond of benzoic-acid crystals, a system which has emerged as a particularly suitable model since proton transfer occurs in a near symmetric double-well potential. The influence of quantum tunnelling was revealed and investigated in these experiments. This work provides an experimental benchmark for theoretical descriptions of translational proton-tunnelling. (author)

354

ChemTeacher Resource: Flash Interactive Digital Overheads  

Science.gov (United States)

Allows the user to interactively and visually learn chemistry. Subtopics include Microscpic World, Atomic Structure, Molecular Structure, Intermolecular Forces, Chemical Reactions, Chemical Kinetics, Chemical Equilibrium

2012-08-01

355

Cosmological Evolution of Interacting Phantom Energy with Dark Matter  

CERN Document Server

We investigate the cosmological evolution of an interacting phantom energy model in which the phantom field has interaction with the dark matter. We discuss the existence and stability of scaling solutions for two types of specific interactions. One is motivated by the conformal transformation in string theory and the other is motivated by analogy with dissipation. In the former case, there exist no scaling solutions. In the latter case, there exist stable scaling solutions, which may give a phenomenological solution of the coincidence problem. Furthermore, the universe either accelerates forever or ends with a singularity, which is determined by not only the model parameters but also the initial velocity of the phantom field.

Guo, Z K; Zhang, Y Z; Guo, Zong-Kuan; Cai, Rong-Gen; Zhang, Yuan-Zhong

2004-01-01

356

Effective ?-? t-matrix interaction at medium energies  

International Nuclear Information System (INIS)

The ?-? transition operator-effective interaction, t??(E, r vector) has been evaluated using phenomenological ?-? optical potentials at several bombarding energies, E? from 77 to 200 MeV. The results are obtained by solving the Schroedinger equation with appropriate optical potentials for various partial waves and then clubbing these with their respective optical potentials and initial state plane waves. The change of the ?-? optical potential with or without hard core has been shown to influence the effective ?-? t-matrix interactions drastically. The behaviour of the calculated t??(E, r vector) effective interaction indicates towards a solution of the large anomalies found in the (?, 2?) reaction analyses. (author)

357

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)

358

Strong interactions studies with medium energy probes  

International Nuclear Information System (INIS)

This progress report refers to the period August 1992 to August 1993, which includes the first year of the three-year period December 1, 1992--November 30, 1995 of the existing research contract. As anticipated in the 1992--1995 proposal the major preoccupation during 1992--1993 was with Fermilab experiment E760. This experiment, whose primary objective is to make very high-resolution study of Charmonium Spectroscopy via proton-antiproton annihilations, has turned out to be a veritable gold-mine of exciting hadronic physics in other areas as well. These include the proton from factor in the time-life region, proton-antiproton forward scattering, QCD scaling laws, and light quark spectroscopy. A large fraction of the data from E760 have been analyzed during this year, and several papers have been published. In addition to the E760 experiment at Fermilab continued progress was made earlier nuclear physics-related experiments at LAMPF, MIT, and NIKHEF, and their results for publication. Topics include high- resolution electron scattering, quasi-free electron scattering and low-energy pion double charge exchange

359

Spectroscopic and ab initio investigation of 2,6-difluorophenylacetylene-amine complexes: coexistence of C-H···N and lone-pair···? complexes and intermolecular coulombic decay.  

Science.gov (United States)

Binary complexes of 2,6-difluorophenylacetylene with methylamine, dimethylamine, trimethylamine and triethylamine were investigated using one colour resonant two photon ionization and infrared-optical double resonance spectroscopic techniques combined with high level ab initio calculations. All four amines form CAc-H···N hydrogen-bonded complexes. Additionally trimethylamine and triethylamine form complexes characterized by Lp···? interactions, due to the electron deficient nature of the phenyl ring of 2,6-difluorophenylacetylene. The Lp···? interacting structure of the 2,6-difluorophenylacetylene-trimethylamine complex is about 1.5 kJ mol(-1) higher in energy than the CAc-H···N hydrogen-bonded structure, which is the global minimum. Energy decomposition analysis indicates that the electrostatics and dispersion interactions favour the formation of CAc-H···N and Lp···? complexes, respectively. Interestingly the CAc-H···N hydrogen-bonded complex of 2,6-difluorophenylacetylene-triethylamine showed a smaller shift in the acetylenic C-H stretching frequency than the 2,6-difluorophenylacetylene-trimethylamine complex. The observed fragmentation of the binary complexes of 2,6-difluorophenylacetylene with the four amines following resonant two-photon ionization can be explained on the basis of the intermolecular coulombic decay process. PMID:25407433

Mondal, Sohidul Islam; Dey, Arghya; Sen, Saumik; Patwari, G Naresh; Ghosh, Debashree

2015-01-01

360

Constraints on interacting Dark Energy models from galaxy rotation curves  

International Nuclear Information System (INIS)

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

361

Partonic description of soft high energy pp interactions  

CERN Document Server

We discuss how the main features of high-energy `soft' and `semihard' pp collisions may be described in terms of parton cascades and multi-Pomeron exchange. The interaction between Pomerons produces an effective infrared cutoff, k_sat, by the absorption of low k_t partons. This provides the possibility of extending the parton approach, used for `hard' processes, to also describe high-energy soft and semihard interactions. We outline a model which incorporates these features. Finally, we discuss what the most recent LHC measurements in the soft domain imply for the model.

Martin, A D; Ryskin, M G

2012-01-01

362

Neutral current neutrino-nucleus interactions at high energies  

International Nuclear Information System (INIS)

We present a QCD analysis of the neutral current (NC) 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. It is shown that at small x, the NC boson-nucleon cross section should exhibit the geometric scaling property that has important consequences for ultrahigh energy neutrino phenomenology.

363

Interactions of Policies for Renewable Energy and Climate  

Energy Technology Data Exchange (ETDEWEB)

This paper explores the relationships between climate policy and renewable energy policy instruments. It shows that, even where CO2 emissions are duly priced, specific incentives for supporting the early deployment of renewable energy technologies are justified by the steep learning curves of nascent technologies. This early investment reduces costs in the longer term and makes renewable energy affordable when it needs to be deployed on a very large scale to fully contribute to climate change mitigation and energy security. The paper also reveals other noteworthy interaction effects of climate policy and renewable policy instruments on the wholesale electricity prices in deregulated markets, which open new areas for future research.

NONE

2011-07-01

364

Wormhole solutions supported by interacting dark matter and dark energy  

OpenAIRE

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 ...

Folomeev, Vladimir; Dzhunushaliev, Vladimir

2013-01-01

365

Quantification of protein interaction in living cells by two-photon spectral imaging with fluorescent protein fluorescence resonance energy transfer pair devoid of acceptor bleed-through.  

Science.gov (United States)

Fluorescence resonance energy transfer (FRET) between fluorescent proteins (FPs) is a powerful method to visualize and quantify protein-protein interaction in living cells. Unfortunately, the emission bleed-through of FPs limits the usage of this complex technique. To circumvent undesirable excitation of the acceptor fluorophore, using two-photon excitation, we searched for FRET pairs that show selective excitation of the donor but not of the acceptor fluorescent molecule. We found this property in the fluorescent cyan fluorescent protein (CFP)/yellow fluorescent protein (YFP) and YFP/mCherry FRET pairs and performed two-photon excited FRET spectral imaging to quantify protein interactions on the later pair that shows better spectral discrimination. Applying non-negative matrix factorization to unmix two-photon excited spectral imaging data, we were able to eliminate the donor bleed-through as well as the autofluorescence. As a result, we achieved FRET quantification by means of a single spectral acquisition, making the FRET approach not only easy and straightforward but also less prone to calculation artifacts. As an application of our approach, the intermolecular interaction of amyloid precursor protein and the adaptor protein Fe65 associated with Alzheimer's disease was quantified. We believe that the FRET approach using two-photon and fluorescent YFP/mCherry pair is a promising method to monitor protein interaction in living cells. PMID:22076866

Kim, Jiho; Li, Xiaolan; Kang, Moon-Sik; Im, Kang-Bin; Genovesio, Auguste; Grailhe, Regis

2012-02-01

366

Dielectric spectroscopy investigation of ion-containing and intermolecular hydrogen-bonded polymer systems  

Science.gov (United States)

Ion-containing and intermolecular hydrogen-bonded polymers are used widely in a variety of industrial and commercial applications, from food packaging to battery electrolytes to pharmaceuticals. Yet the dynamics of these polymers, which are both complex and important to the application, are poorly understood. This thesis provides the first systematic study of the dynamics of several ion-containing and intermolecular hydrogen-bonded polymers by broadband dielectric relaxation spectroscopy. The systems under consideration include sulfonated polystyrene (SPS) in acid (SPS-H) and neutralized forms, and mixtures of poly(2-vinylpyridine) (P2VPy) with lithium perchlorate (LiClO4) and low molecular weight phenolic molecules. Dynamic mechanical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, small-angle X-ray scattering and wide-angle X-ray diffraction were employed in a complementary role. Multiple relaxations were generally observed at high temperatures. For SPS ionomers, the segmental process, Maxwell-Wagner-Sillars interfacial polarization, and electrode polarization were detected. Three relaxations were also found in spectra of SPS-H, attributed to the segmental process, hydrogen bond association/dissociation, and electrode polarization. Three dielectric relaxations above the segmental process were observed for P2VPy-LiClO4 mixtures: ion-mode relaxation, slow hindered segmental relaxation and electrode polarization. However, only electrode polarization was observed above the segmental relaxation for all P2VPy--small phenolic molecule mixtures, except P2VPy + 10 mol% 2,3,3,4,4,5-hexahydroxybenzophenone. This mixture exhibited an additional relaxation due to Maxwell-Wagner-Sillars interfacial polarization, arising from the existence of phase-separated complexes within the P2VPy matrix. Sub-Tg local relaxations were suppressed by ionic intermolecular interactions for SPS ionomers and P2VPy-LiClO4 mixtures. Intermolecular hydrogen bonding also suppressed the local relaxation in P2VPy-small phenolic molecule mixtures by decreasing the mobility of the pyridine-side groups. Both the concentration of small phenolic molecules and the number of hydroxyl groups per molecule played an important role in suppression of the local relaxation, which was significant for all mixtures where the small molecules contained more than one hydroxyl group per molecule.

Atorngitjawat, Pornpen

367

Interacting agegraphic dark energy models in phase space  

International Nuclear Information System (INIS)

Agegraphic dark energy, has been recently proposed, based on the so-called Karolyhazy uncertainty relation, which arises from quantum mechanics together with general relativity. In the first part of the article we study the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. The phase space analysis was made and the critical points were found, one of which is the attractor corresponding to an accelerated expanding Universe. Recent observations of near supernova show that the acceleration of Universe decreases. This phenomenon is called the transient acceleration. In the second part of Article we consider the 3-component Universe composed of a scalar field, interacting with the dark matter on the agegraphic dark energy background. We show that the transient acceleration appears in frame of such a model. The obtained results agree with the observations

368

Self-interaction errors in nuclear energy density functionals  

OpenAIRE

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

369

The interaction between emissions trading and energy and competition policies  

OpenAIRE

Emissions trading is a “cap and trade” regulation aimed at reducing the cost of meeting environmental targets. This paper studies how this regulation interacts with energy and competition policies. Two vertically related and imperfectly competitive markets are investigated: 1) the electricity market (output market); 2) the market for natural gas (input market). The effect of energy policy is simulated by assuming that the supporting scheme is able to improve the competitivenes...

Gulli?, Francesco

2011-01-01

370

Distributed energy resources in grid interactive AC microgrids  

OpenAIRE

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

371

Sustainable Interactions : Studies in the Design of Energy Awareness Artefacts  

OpenAIRE

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 ...

Broms, Loove

2011-01-01

372

Photoinduced tautomerism of 2,6-dicarbomethoxyphenol in DMF–water mixtures: Perturbation from intermolecular processes  

International Nuclear Information System (INIS)

In this paper, we report the spectral signatures of photoinduced tautomerism of 4-methyl-2,6-dicarbomethoxyphenol (CMOH) in DMF–water mixtures with varying compositions. Excited state intramolecular proton transfer (ESIPT) reaction of CMOH has been observed in bulk DMF, indicated by dual fluorescence from its normal and tautomeric forms while only a single emission peak is observed in water from its anionic species. Binary mixture of a polar aprotic (DMF) and a polar protic (water) solvent gives rise to a competition between intramolecular and intermolecular hydrogen bonding (with media) processes of the probe. This competition is found to be largely dependent on the proton affinity of the media and also on the excitation energy. Solvent separated ion pair and intermolecularly H-bonded CMOH–Solvent complex have been detected in the excited state at specific solvent compositions that are converted to the anionic form due to the change in excitation wavelengths. The formation of hydrogen bonded 1:1 molecular clusters of different rotamers of CMOH with DMF and water in the ground state has been investigated using quantum chemical calculations. A combined experimental and theoretical analysis indicates that the HOMO to LUMO transitions dictate the electronic absorption profiles of the CMOH–DMF and CMOH–water clusters. These findings are expected to shed light on the mechanism of acid–base reactions of several hydrogen bonded systems that are part of many biologically relevant processes. -- Highlights: •Photoinduced tautomerization of CMOH has been studied in DMF–water mixture. •CMOH forms 1:1 molecular clusters with DMF and water. •The competition between intra- and intermolecular hydrogen bonding is revealed. •HOMO to LUMO transition dictates the absorption spectra of CMOH in DMF and water

373

Intermolecular stabilization of 3,3'-diamino-4,4'-azoxyfurazan (DAAF) compressed to 20 GPa.  

Science.gov (United States)

The room temperature stability of 3,3'-diamino-4,4'-azoxyfurazan (DAAF) has been investigated using synchrotron far-infrared, mid-infrared, Raman spectroscopy, and synchrotron X-ray diffraction (XRD) up to 20 GPa. The as-loaded DAAF samples exhibited subtle pressure-induced ordering phenomena (associated with positional disorder of the azoxy "O" atom) resulting in doubling of the a-axis, to form a superlattice similar to the low-temperature polymorph. Neither high pressure synchrotron XRD, nor high pressure infrared or Raman spectroscopies indicated the presence of structural phase transitions up to 20 GPa. Compression was accommodated in the unit cell by a reduction of the c-axis between the planar DAAF layers, distortion of the ?-angle of the monoclinic lattice, and an increase in intermolecular hydrogen bonding. Changes in the ring and -NH2 deformation modes and increased intermolecular hydrogen bonding interactions with compression suggest molecular reorganizations and electronic transitions at ? 5 GPa and ? 10 GPa that are accompanied by a shifting of the absorption band edge into the visible. A fourth-order Birch-Murnaghan fit to the room temperature isotherm afforded an estimate of the zero-pressure isothermal bulk modulus, K0 = 12.4 ± 0.6 GPa and its pressure derivative K0' = 7.7 ± 0.3. PMID:25011055

Chellappa, Raja S; Dattelbaum, Dana M; Coe, Joshua D; Velisavljevic, Nenad; Stevens, Lewis L; Liu, Zhenxian

2014-08-01

374

Intra- and intermolecular hydrogen bonding in acetylacetone and benzoylacetone derived enaminone derivatives  

Science.gov (United States)

The structure and hydrogen bonding in solution of acetylacetone and benzoylacetone derived enaminone derivatives, 1a-1d and 2a-2d, have been studied by a combination of experimental (NMR and UV spectroscopies) and theoretical (PM6 and DFT) methods. It has been shown that all studied compounds predominantly existed in the localised keto-amine tautomeric form in solution as found also in the solid state. Significant line-broadening and down-field chemical shifts of NH and OH protons have strongly indicated that both groups formed hydrogen bonds, which has further been supported by quantum chemical calculations. Temperature and concentration dependent NMR measurements have pointed towards the fact that NH protons are engaged in strong intramolecular hydrogen bonds of the NH⋯Odbnd C type in both solvents. On the other hand, OH protons are involved in weaker intermolecular hydrogen bonding with solvent molecules in DMSO, while in chloroform intermolecular interactions between two molecules dominate. The results presented in this paper can be used for better understanding and further exploiting properties these ligands possess, especially their bioactivity.

Lazi?, Vedrana; Jurkovi?, Mihaela; Jedna?ak, Tomislav; Hrenar, Tomica; Vukovi?, Jelena Parlov; Novak, Predrag

2015-01-01

375

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

376

Molecular Associations Determined from Free Energy Calculations  

Science.gov (United States)

In this chapter we describe the development and implementation of a computational method able to produce free energies in multiple dimensions, descriptively named the free energies from adaptive reaction coordinate forces method (FEARCF). We use this method to investigate the structure of associative liquids such as water. Important chemical phenomena such as the free energy of ion pairing in methanol have been studied using the FEARCF method as have the reaction surfaces of chemical reactions in solution. More recently, a multidimensional intermolecular orientational free energy was developed from FEARCF. This multidimensional intermolecular free energy W(r, ?1, ?2, ?) provides means to measure the orientationally dependent molecular interactions, that are necessary for applications in complex systems such as proteins, where molecular anisotropic features govern the structure. It is a highly informative free energy volume and is shown to probe the thermodynamic nature of water's tetrahedral local structure.

Naidoo, Kevin J.

377

Intermolecular ?-strand networks avoid hub residues and favor low interconnectedness: a potential protection mechanism against chain dissociation upon mutation.  

Science.gov (United States)

Altogether few protein oligomers undergo a conformational transition to a state that impairs their function and leads to diseases. But when it happens, the consequences are not harmless and the so-called conformational diseases pose serious public health problems. Notorious examples are the Alzheimer's disease and some cancers associated with a conformational change of the amyloid precursor protein (APP) and of the p53 tumor suppressor, respectively. The transition is linked with the propensity of ?-strands to aggregate into amyloid fibers. Nevertheless, a huge number of protein oligomers associate chains via ?-strand interactions (intermolecular ?-strand interface) without ever evolving into fibers. We analyzed the layout of 1048 intermolecular ?-strand interfaces looking for features that could provide the ?-strands resistance to conformational transitions. The interfaces were reconstructed as networks with the residues as the nodes and the interactions between residues as the links. The networks followed an exponential decay degree distribution, implying an absence of hubs and nodes with few links. Such layout provides robustness to changes. Few links per nodes do not restrict the choices of amino acids capable of making an interface and maintain high sequence plasticity. Few links reduce the "bonding" cost of making an interface. Finally, few links moderate the vulnerability to amino acid mutation because it entails limited communication between the nodes. This confines the effects of a mutation to few residues instead of propagating them to many residues via hubs. We propose that intermolecular ?-strand interfaces are organized in networks that tolerate amino acid mutation to avoid chain dissociation, the first step towards fiber formation. This is tested by looking at the intermolecular ?-strand network of the p53 tetramer. PMID:24733378

Feverati, Giovanni; Achoch, Mounia; Vuillon, Laurent; Lesieur, Claire

2014-01-01

378

Quantifying stickiness: thermodynamic characterization of intramolecular domain interactions to guide the design of förster resonance energy transfer sensors.  

Science.gov (United States)

The introduction of weak, hydrophobic interactions between fluorescent protein domains (FPs) can substantially increase the dynamic range (DR) of Förster resonance energy transfer (FRET)-based sensor systems. Here we report a comprehensive thermodynamic characterization of the stability of a range of self-associating FRET pairs. A new method is introduced that allows direct quantification of the stability of weak FP interactions by monitoring intramolecular complex formation as a function of urea concentration. The commonly used S208F mutation stabilized intramolecular FP complex formation by 2.0 kCal/mol when studied in an enhanced cyan FP (ECFP)-linker-enhanced yellow FP (EYFP) fusion protein, whereas a significantly weaker interaction was observed for the homologous Cerulean/Citrine FRET pair (?G0(o-c) = 0.62 kCal/mol). The latter effect could be attributed to two mutations in Cerulean (Y145A and H148D) that destabilize complex formation with Citrine. Systematic analysis of the contribution of residues 125 and 127 at the dimerization interface in mOrange.linker.mCherry fusion proteins yielded a toolbox of new mOrange-mCherry combinations that allowed tuning of their intramolecular interaction from very weak (?G0(o-c) = .0.39 kCal/mol) to relatively stable (?G0(o-c) = 2.2 kCal/mol). The effects of these mutations were also studied by monitoring homodimerization of mCherry variants using fluorescence anisotropy. These mutations affected intramolecular and intermolecular domain interactions similarly, although FP interactions were found to be stronger in the latter. The knowledge thus obtained allowed successful construction of a red-shifted variant of the bile acid FRET sensor BAS-1 by replacement of the self-associating Cerulean-Citrine pair by mOrange.mCherry variants with a similar intramolecular affinity. Our findings thus allow a better understanding of the subtle but important role of intramolecular domain interactions in current FRET sensors and help guide the construction of new sensors using modular design strategies. PMID:25216081

Lindenburg, Laurens H; Malisauskas, Mantas; Sips, Tari; van Oppen, Lisanne; Wijnands, Sjors P W; van de Graaf, Stan F J; Merkx, Maarten

2014-10-14

379

U'(1) Neutrino Interaction at Very Low Energies  

CERN Document Server

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 of the cosmic neutrinos background which allow the interaction between neutrinos, above this temperature this interaction disappears. The magnetic flux is quantized in terms of the hidden charge. We found an approximate relation between the order parameter and neutrino condensate $\\langle{\\bar \

Gamboa, J

2014-01-01

380

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.)

381

Benchmark data sets on noncovalent interaction energies and their accuracy.  

Czech Academy of Sciences Publication Activity Database

New Orleans : American Chemical Society, 2013. s. 32phys. ISSN 0065-7727. [National Spring Meeting of the American Chemical Society /245./. 07.04.2013-11.04.2013, New Orleans] Institutional support: RVO:61388963 Keywords : noncovalent interaction energies * benchmark data Subject RIV: CF - Physical ; Theoretical Chemistry

?ezá?, Jan; Riley, K. E.; Hobza, Pavel

382

Polarization phenomena in electromagnetic interactions at intermediate energies  

Energy Technology Data Exchange (ETDEWEB)

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.

Burkert, V.

1990-01-01

383

Dimensionality of Local Minimizers of the Interaction Energy  

Science.gov (United States)

In this work we consider local minimizers (in the topology of transport distances) of the interaction energy associated with a repulsive-attractive potential. We show how the dimensionality of the support of local minimizers is related to the repulsive strength of the potential at the origin.

Balagué, D.; Carrillo, J. A.; Laurent, T.; Raoul, G.

2013-09-01

384

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

385

Wormhole solutions supported by interacting dark matter and dark energy  

Science.gov (United States)

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; Dzhunushaliev, Vladimir

2014-03-01

386

Nuclear tensor interaction in a covariant energy density functional  

Science.gov (United States)

The origin of the nuclear tensor interaction in the covariant energy density functional (EDF) is presented in this work, associated with the Fock diagrams of Lorentz scalar and vector couplings. With this newly obtained relativistic formalism of the nuclear tensor interaction, more distinct tensor effects are found in the Fock diagrams of the Lorentz scalar and vector couplings, as compared to the Lorentz pseudovector and tensor channels. A unified and self-consistent treatment of both the nuclear tensor and spin-orbit interactions, which dominate the spin-dependent features of the nuclear force, is then achieved by the relativistic models. Moreover, careful analysis of the tensor strengths indicates the reliability of the nuclear tensor interaction in the covariant EDF for exploring the nuclear structure, excitation, and decay modes.

Jiang, Li Juan; Yang, Shen; Sun, Bao Yuan; Long, Wen Hui; Gu, Huai Qiang

2015-03-01

387

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.)

388

Integrated methodology for assessing energy-economy interactions  

Energy Technology Data Exchange (ETDEWEB)

Brookhaven National Lab. (BNL) has collaborated in development of an integrated technological and econometric representation of the nation's energy and economic systems. Among the applications of this integrated methodology are the assessment of energy-economy interactions, benefit/cost analyses of alternative energy policies, and multi-objective supply and demand studies relating to energy R and D and technology change. The integrated analytical system is comprised of three component models. The economic growth model included in this framework is the Dale W. Jorgenson Associates (DJA) Long-term Interindustry Transactions Model (LITM). The LITM model provides a flexible, interindustry representation of sectoral production and final demand, and captures the combined influences of productivity, investment, and labor supply on the long-term expansion of US productive capacity. The second component of this model system is a detailed technological model of energy supply, conversion, and end-use demand. The Time-stepped Energy System Optimization Model (TESOM) developed by BNL represents the full feasible range of energy resource and technology substitutions for the US energy system. The final component of this model framework is the input-output model developed jointly by BNL and the Univ. of Illinois. This detailed input-output model of the structure of the US economy maps the outputs of the conventional energy-supply and -conversion sectors into non-substitutable energy-service demands for each interindustry sector and final demand. The BNL/DJA combined model system provides a comprehensive long-run representation of US energy consumption and energy-economy interactions.

Lukachinski, J.; Groncki, P.J.; Tessmer, R.G. Jr.; Goettle, R.J. IV; Hudson, E.A.

1979-01-01

389

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**

390

Local energy transfer and nonlocal interactions in homogeneous, isotropic turbulence  

Science.gov (United States)

Detailed computations were made of energy transfer among the scales of motion in incompressible turbulent fields at low Reynolds numbers, generated by direct numerical simulations. It was observed that, although the transfer resulted from triad interactions that were nonlocal in k space, the energy always transferred locally. The energy transfer calculated from the eddy-damped quasi-normal Markovian (EDQNM) theory of turbulence at low Reynolds numbers is in excellent agreement with the results of the numerical simulations. At high Reynolds numbers, the EDQNM theory predicts the same transfer mechanism in the inertial range that is observed at low Reynolds numbers.

Domaradzki, J. Andrzej; Rogallo, Robert S.

1990-01-01

391

HIGH ENERGY NUCLEAR INTERACTIONS AND QCD : AN INTRODUCTION.  

Energy Technology Data Exchange (ETDEWEB)

The goal of these lectures, oriented towards the students just entering the field, is to provide an elementary introduction to QCD and the physics of nuclear interactions at high energies. We first introduce the general structure of QCD and discuss its main properties. Then we proceed to Glauber multiple scattering theory which lays the foundation for the theoretical treatment of nuclear interactions at high energies. We introduce the concept of Gribov's inelastic shadowing, crucial for the understanding of quantum formation effects. We outline the problems facing Glauber approach at high energies, and discuss how asymptotic freedom of QCD helps to resolve them, introducing the concepts of parton saturation and color glass condensate.

KHARZEEV,D.E.; RAUFEISEN,J.

2002-01-07

392

Interaction of two walkers: Wave-mediated energy and force  

CERN Document Server

A bouncing droplet, self-propelled by its interaction with the waves it generates, forms a classical wave-particle association called a "walker." Previous works have demonstrated that the dynamics of a single walker is driven by its global surface wave field that retains information on its past trajectory. Here, we investigate the energy stored in this wave field for two coupled walkers and how it conveys an interaction between them. For this purpose, we characterize experimentally the "promenade modes" where two walkers are bound, and propagate together. Their possible binding distances take discrete values, and the velocity of the pair depends on their mutual binding. The mean parallel motion can be either rectilinear or oscillating. The experimental results are recovered analytically with a simple theoretical framework. A relation between the kinetic energy of the droplets and the total energy of the standing waves is established.

Borghesi, Christian; Labousse, Matthieu; Eddi, Antonin; Fort, Emmanuel; Couder, Yves

2014-01-01

393

Low-energy pion interaction with lightest nuclei  

International Nuclear Information System (INIS)

The present state of low-energy pion interaction with 2H, 3He, 4He nuclei is considered. Calculation of differential cross sections (??/d?)?± of elastic scattering of positive and negative pions on 4He nucleus with the energy of T?=30 MeV (in lab.syst.) and variation of inelasticity parameters with angular moment l=0 and 1 are presented. Highcriticality of estimations of total cross section for (?, 4He) reaction extracted from elastic scattering analysis to (d?/d?)?± behaviour in minimum range is detected. Some actual problems of experimental and theoretial studies of low-energy pion interaction with the lightest nuclei are discussed. 25 refs.; 10 figs.; 1 tab

394

Importance of the donor:fullerene intermolecular arrangement for high-efficiency organic photovoltaics.  

Science.gov (United States)

The performance of organic photovoltaic (OPV) material systems are hypothesized to depend strongly on the intermolecular arrangements at the donor:fullerene interfaces. A review of some of the most efficient polymers utilized in polymer:fullerene PV devices, combined with an analysis of reported polymer donor materials wherein the same conjugated backbone was used with varying alkyl substituents, supports this hypothesis. Specifically, the literature shows that higher-performing donor-acceptor type polymers generally have acceptor moieties that are sterically accessible for interactions with the fullerene derivative, whereas the corresponding donor moieties tend to have branched alkyl substituents that sterically hinder interactions with the fullerene. To further explore the idea that the most beneficial polymer:fullerene arrangement involves the fullerene docking with the acceptor moiety, a family of benzo[1,2-b:4,5-b']dithiophene-thieno[3,4-c]pyrrole-4,6-dione polymers (PBDTTPD derivatives) was synthesized and tested in a variety of PV device types with vastly different aggregation states of the polymer. In agreement with our hypothesis, the PBDTTPD derivative with a more sterically accessible acceptor moiety and a more sterically hindered donor moiety shows the highest performance in bulk-heterojunction, bilayer, and low-polymer concentration PV devices where fullerene derivatives serve as the electron-accepting materials. Furthermore, external quantum efficiency measurements of the charge-transfer state and solid-state two-dimensional (2D) (13)C{(1)H} heteronuclear correlation (HETCOR) NMR analyses support that a specific polymer:fullerene arrangement is present for the highest performing PBDTTPD derivative, in which the fullerene is in closer proximity to the acceptor moiety of the polymer. This work demonstrates that the polymer:fullerene arrangement and resulting intermolecular interactions may be key factors in determining the performance of OPV material systems. PMID:24932575

Graham, Kenneth R; Cabanetos, Clement; Jahnke, Justin P; Idso, Matthew N; El Labban, Abdulrahman; Ngongang Ndjawa, Guy O; Heumueller, Thomas; Vandewal, Koen; Salleo, Alberto; Chmelka, Bradley F; Amassian, Aram; Beaujuge, Pierre M; McGehee, Michael D

2014-07-01

395

Low-energy anti-kaon nucleon and nucleus interaction  

Science.gov (United States)

Central importance for the physics of strong interaction has the dynamics driven by chiral symmetry breaking in low-energy QCD. Valuable information is provided by high precision x-ray studies of the strong interaction at threshold. In this context precision measurements of the strong interaction induced energy shift and width in kaonic atoms are conducted at LNF/Italy at present and at J-PARC/Japan in the future. New dedicated experimental search for bound systems with anti-kaons are under way at GSI and will be conducted at LNF and J-PARC. These studies will provide urgently needed data for theoretical studies and will open the way to a detailed insight in the low energy regime of the strong force with anti-kaons. Especially interesting are nuclear systems involving strangeness and bound by the strong force, called kaonic nuclear clusters. At present this topic is in intense discussion and the search for these systems is conducted in new experiments (e.g. FOPI at GSI). LEANNIS, an international scientific network in Hadronphysics2 within the European Framework Program FP7, will bring together experimentalists and theorists to perform joint research work on the anti-kaon interaction with nucleons and nuclei. This presentation gives an overview on the open problems and and will present the status and outlook of research activities in this challenging field which is inherently connected with few-body physics.

Marton, J.

2010-04-01

396

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

397

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 “Interactive Energy Planning” 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

398

Intra- and intermolecular charge transfer in aggregates of tetrathiafulvalene-triphenylmethyl radical derivatives in solution.  

Science.gov (United States)

An extensive investigation of aggregation phenomena occurring in solution for a family of electron donor-acceptor derivatives, based on polychlorotriphenylmethyl radicals (PTM) linked via a vinylene-bridge to tetrathiafulvalene (TTF) units, is presented. A large set of temperature and/or concentration dependent optical absorption and electron spin resonance (ESR) spectra in a solution of dyads bearing different number of electrons and/or with a hydrogenated PTM residue offer reliable information on the formation of homo dimers and mixed valence dimers. The results shed light on the reciprocal influence of intramolecular electron transfer (IET) within a dyad and the intermolecular charge transfer (CT) occurring in a dimer between the TTF residues and are rationalized based on a theoretical model that describes both interactions. PMID:23517105

Guasch, Judith; Grisanti, Luca; Souto, Manuel; Lloveras, Vega; Vidal-Gancedo, José; Ratera, Imma; Painelli, Anna; Rovira, Concepció; Veciana, Jaume

2013-05-01

399

Dielectric behaviour and intermolecular association between L(+) ascorbic acid and ethanol  

International Nuclear Information System (INIS)

In order to determine the dipole moment of L(+) ascorbic acid and the relation to its structure the experimental variations of permitivities, refractive indices and specific volumes of a series of dilute ethanolic solutions at 25 deg C were examined. The average moment (?) using Buckingham equation was found to be 5,58 D considering the spherical approximation and 7,81 D if the ellipsoidal form factor was considered. The calculated ? value through vectorial addition was 4,98 D. The solute partial molal volume in the studied range was calculated to be 94,73 cm3 instead of the theoretical value of 106,71 cm3. Both discrepancies are attributed to intermolecular solute-solvent interactions. A possible electronic displacement which favours hydrogen bonding with the solvent is postulated. (Author)

400

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

401

Fast electron energy distribution in femtosecond laser plasma interactions  

International Nuclear Information System (INIS)

The energy distributions of fast electrons in fs laser-plasma interactions have been measured using the magnetic spectrometers with various magnetic fields, fitted with the LiF thermoluminescent dosimeters (TLDs). The results show the consistency and the important characters of energy distribution of fast electrons, which are similar to those of the experiment and simulation made by others. There is a concavity at 40 keV, which is due to the return current of cold electrons; and a local plateau of electrons with energies 100-350 keV, which is produced by several acceleration mechanisms in energy distribution. The effective temperature of fast electrons is consistent with the temperature scaling of the resonance absorption, which is due to Landau damping or wave breaking. (authors)

402

Low-Energy Interaction of Anti-Kaons  

International Nuclear Information System (INIS)

A usr the physics of strong interaction has the dynamics driven by chiral symmetry breaking in low-energy QCD. High precision measurements of the antikaon interaction with nucleons and nuclei - like SIDDHARTA at LNF/Italy and E17 at J-PARC/Japan - open the way to study the low energy regime of strong interaction involving strangeness. Especially interesting are nuclear systems (KNCs, kaonic nuclear clusters) involving strangeness and bound by the strong force. At present this topic is in lively discussion and the search for KNCs is conducted in new experiments (e.g. FOPI at GSI, AMADEUS at LNF, E15 at J-PARC). An international scientific network (LEANNIS) in Hadron physics 2 of the European Framework Program FP7 will bring together experimentalists and theorists for joint work on the antikaon interaction with nucleons and nuclei. This talk will give an overview on open problems and will present research activities in this challenging field. The progress in precision spectroscopy of kaonic atoms will be discussed in detail.

403

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

404

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

405

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

406

Electrostatic free energy of interacting ionizable double layers  

OpenAIRE

The electrostatic contribution to the interaction free energy of charge-regulating materials, similar as well as dissimilar, contains electric work as well as chemical work and can be obtained from an integration over the diffuse part of the double layer together with a summation of the surface contribution to the free energy over the two surfaces. Examples for the surface contribution are given for acid, base, zwitterionic, and amphoteric (1-pK and 2-pK) materials for a diffuse double layer ...

Biesheuvel, P. M.

2004-01-01

407

Distributed energy resources in grid interactive AC microgrids  

DEFF Research Database (Denmark)

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 are described. Instantaneous load sharing strategies among DER units in the islanded microgrid operations are discussed pointing out the importance of closed loop system output impedance for the power electronics interfaced DER units.

Wang, Xiongfei; Guerrero, Josep

2010-01-01

408

The halo mass function in interacting Dark Energy models  

OpenAIRE

We present a detailed investigation of the effects that a direct interaction between Dark Energy (DE) and Cold Dark Matter (CDM) particles imprints on the Halo Mass Function (HMF) of groups and clusters of galaxies. Making use of the public halo catalogs of the {\\small CoDECS} simulations, we derive the HMF for several different types of coupled DE scenarios both based on the FoF algorithm and on the SO halo identification for different values of the overdensity threshold $\\...

Cui, Weiguang; Baldi, Marco; Borgani, Stefano

2012-01-01

409

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

OpenAIRE

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

410

Nucleus-nucleus interactions in the transition energy regime  

International Nuclear Information System (INIS)

There are at least two ways for studying large interactions in nucleus-nucleus collisions. One way is to use the method of angular correlations between fission fragments. The aim of the experiments presented here was to make a survey on the role of the various experimental parameters. In that respect three targets have been studied and different projectiles and bombarding energies have been used. Results are presented and discussed

411

The two gluon exchange model for ?? interactions at high energies  

International Nuclear Information System (INIS)

The model of ?? pointlike interactions via the two gluon exchange is presented. The model is developed using the Sudakov techniques for the high energy limit. Its predictions for the experimentally measured quantities of ?inclusivetot and the structure function F2(x,Q2) are found in a good agreement with the predictions of GVDM model. Used together with the QPM it can explain the experimental data for the whole kinematical region available in the recent experiments. 19 refs., 12 figs. (author)

412

Observational constraints on a holographic, interacting dark energy model  

OpenAIRE

We constrain an interacting, holographic dark energy model, first proposed by two of us in [1], with observational data from supernovae, CMB shift, baryon acoustic oscillations, x-rays, and the Hubble rate. The growth function for this model is also studied. The model fits the data reasonably well but still the conventional $\\Lambda$CDM model fares better. Nevertheless, the holographic model greatly alleviates the coincidence problem and shows compatibility at $1\\sigma$ conf...

Dura?n, Iva?n; Pavo?n, Diego; Zimdahl, Winfried

2010-01-01

413

Two-particle binding energy of interacting Bose gases  

OpenAIRE

The pole of the two-particle T-matrix including the influence of the surrounding medium is analyzed for an interacting Bose gas. The phase diagram of the Bose -Einstein condensation (BEC) depending on the temperature, density, scattering length, and momentum is derived from this pole. The critical momentum for the occurrence of superfluidity is obtained in this way. As a new observation a two- particle binding energy is reported intimately connected with the occurrence of th...

Ma?nnel, K. Morawetz M.; Schreiber, M.; Lipavsky?, P.

2007-01-01

414

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

415

Investigation of dark matter-dark energy interaction cosmological model  

CERN Document Server

In this paper, we test the dark matter-dark energy interacting cosmological model with a dynamic equation of state $w_{DE}(z)=w_{0}+w_{1}z/(1+z)$, using type Ia supernovae (SNe Ia), Hubble parameter data, baryonic acoustic oscillation (BAO) measurements, and the cosmic microwave background (CMB) observation. This interacting cosmological model has not been studied before. The best-fitted parameters with $1 \\sigma$ uncertainties are $\\delta=-0.022 \\pm 0.006$, $\\Omega_{DM}^{0}=0.213 \\pm 0.008$, $w_0 =-1.210 \\pm 0.033$ and $w_1=0.872 \\pm 0.072$ with $\\chi^2_{min}/dof = 0.990$. At the $1 \\sigma$ confidence level, we find $\\delta<0$, which means that the energy transfer prefers from dark matter to dark energy. We also find that the SNe Ia are in tension with the combination of CMB, BAO and Hubble parameter data. The evolution of $\\rho_{DM}/\\rho_{DE}$ indicates that this interacting model is a good approach to solve the coincidence problem, because the $\\rho_{DE}$ decrease with scale factor $a$. The transition r...

Wang, J S

2014-01-01

416

Revisiting the interacting model of new agegraphic dark energy  

Science.gov (United States)

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 ? {de/ ? } ? {dm/1-? } is adopted, which abandons the Hubble expansion rate H and involves both ? de and ? 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 ? de, (B) Q = bH 0 ?? de ? dm, and (C) Q = bH 0 ? dm, which correspond to ? = 1, 1/2, and 0, respectively. The departures of the models from the ?CDM model are measured by the ?BIC and ?AIC values. It is shown that the INADE model is better than the NADE model in the fit, and the INADE(A) model is the best in fitting data among the three cases.

Zhang, JingFei; Zhao, LiAng; Zhang, Xin

2014-01-01

417

Energy interactions in amyloid-like fibrils from NNQQNY.  

Science.gov (United States)

We use large-scale MP2 calculations to analyze the interactions appearing in amyloid fibers, which are difficult to determine experimentally. To this end, dimers and trimers of the hexapeptide NNQQNY from the