ISSN:0026-8976    

DOI:10.1080/00268977700102481

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Modulated Murrell-Shaw-Musher-Amos perturbation theory is used in second order to calculate the interaction energy between two ground-state hydrogen atoms in the region of intermediate internuclear separations from 0 to 6 bohr. Using a small set of variationally optimized two-electron functions accounting for the majority of induction and for spherical and dipole contributions to dispersion, fairly accurate results are obtained for the interaction over the whole range of distances including the united atom. A marked reduction in the induction energy is observed in short range when second-order exchange is introduced.

ISSN:0026-8976    

DOI:10.1080/00268977700102491

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The long-range interactions between ethylene (C2H4) and between pyrazine (C4N2H4) molecules have been calculated in the multipole expansion from LCAO-SCF wave functions on the monomers. In first-order perturbation theory, theR-5andR-7dependent terms have been considered. The second-order energy has been calculated in a new (non-empirical) application of Unsöld's approximation up toR-10terms inclusive.

ISSN:0026-8976    

DOI:10.1080/00268977700102501

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A system of hard spheres in contact with a structureless wall is considered. The potential between the wall and the particles is of Lennard-Jones type. The second, the third and the fourth three-dimensional virial coefficient of the adsorption isotherm are calculated. The result being that over an extremely large temperature range the two-dimensional virial treatment is a rather good approximation. Conclusions are drawn about the deviations from Henry's law and the coverage, which can be described by virial expansions. It is doubted whether, from experimentally determined virial coefficients, information about the potential between the adatoms can be extracted.

ISSN:0026-8976    

DOI:10.1080/00268977700102511

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A system of 500 Lennard-Jones particles has been simulated by computer molecular dynamics. Calculations were made at three densities and three temperatures ranging from below the critical density at high temperature to the triple-point density and temperature. Besides the equilibrium pair-correlation function the dynamical quantities calculated were: the time dependence of the moments <X2> and <X4> of the displacement, velocity autocorrelation function and test particle correlation functions:Fs(k, t) andSs(k, ω). Both the full potential and a truncated one (i.e. without the attractive part) have been used in the calculation to investigate the effects of the attractive part on the above quantities. The results are then compared with the recently developed generalized hard-sphere Enskog theory of dense gases. At low density and without the attractive part the results are in good agreement with theory; however, this is not so in the presence of the attractive part which modifies the detailed dynamical behaviour of the test particle to a considerable extent. At high densities the attractive part is much less important but, as expected, the results do not agree with theory.

ISSN:0026-8976    

DOI:10.1080/00268977700102521

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The properties of a particle undergoing circular rotational motion in anN-fold cosine potential is investigated in detail. The rate equation for the probability function is given and order parameters are defined. The self-correlation functions of cosnϕ and sinnϕ (ϕ is the azimuthal angle) are calculated. The neutron incoherent scattering law is derived. The elastic incoherent structure factor is calculated directly. The jump model amongNequidistant sites and the continuous rotational diffusion model are found as limiting cases. The problem of a more general potential is also discussed.

ISSN:0026-8976    

DOI:10.1080/00268977700102531

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Absolute total elastic cross sections for collisions of O2with He, Ne, Ar, Kr, Xe have been measured in the velocity range from 0·4 to 2·4 km s-1. Except in the O2-He system, all the cross sections show a glory structure, and the van der Waals constants,C6, have been obtained from the average ∼ν-2/5dependence. Total cross sections have been well reproduced by some usual spherically symmetric potential models. Detailed information on the spherical portion of the interaction potential, in the range of the limiting impact parameters, have been extracted.

ISSN:0026-8976    

DOI:10.1080/00268977700102541

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The one-electron hamiltonian method based on the Fletcher-Reeves minimization procedure is considered as applied to orbital optimization in the open-shell SCF theory. Comparison with conventional approaches using special operators is made. The character of convergence for a number of iterative procedures is exemplified by calculating the TCNQ anion in a weak electric field.

ISSN:0026-8976    

DOI:10.1080/00268977700102551

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The method of molecular dynamics has been employed to study the autocorrelation functions (ACF's) of the linear velocity and of the angular momentum for two two-dimensional systems of diatomic molecules. The anisotropic potential used is built from four atom-atom interactions. These are either purely repulsive (R), or repulso-attractive (LJ). Emphasis has been put on the long-time behaviour; for this we have used large systems (1600 molecules). The density lies in the intermediate range.

ISSN:0026-8976    

DOI:10.1080/00268977700102561

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The application of the computer simulation method of molecular dynamics to macromolecules is investigated. The protein trypsin inhibitor (BPTI), consisting of 454 united atoms, is used as an example. Different algorithms for integrating the equations of motion are compared, both theoretically and in practice. It is examined to what extent the chain structure of a macromolecule allows a reduction of the computational effort by the introduction of constraints in the dynamics of the chain.

ISSN:0026-8976    

DOI:10.1080/00268977700102571

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor