摘要:

Wigner's (2n+ 1) rule (stating that the 2nth and/or (2n+ 1)th order perturbation contributions to a non-degenerate energy can be evaluated from a knowledge of the wavefunction throughnth order) is applied to many-body perturbation theory (MBPT). This approach essentially simplifies the calculation of correlation energy to an order higher than the third and reduces the number of required diagrams.

ISSN:0026-8976    

DOI:10.1080/00268978000100121

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The first momentM1(H) of thevs(OH) absorption band of self-associated CD3OH in freon 11 and the corresponding first momentM1(D) of self-associated CH3OD have been measured at 10 K intervals between 160 K and 280 K. The regression of the moments on coth (ħω2/2kT) is close to linear, with correlation coefficients of 0·998 for H and 0·999 for D. The ratioM1(H)/M1(D) is independent of temperature.

ISSN:0026-8976    

DOI:10.1080/00268978000100131

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Neutron diffraction measurements of mixtures of TiCl4/SiCl4and TiCl4/SnCl4liquids have been made using the total scattering spectrometer of the Harwell Electron Linac. The highQ-value (5–20 Å-1) data exhibit a beat effect and have been analysed in terms of summed molecular form factors. The bond-length parameters are found to be in good agreement with other values and confirm the treatment adopted in the analysis of the data for the pure liquids.

ISSN:0026-8976    

DOI:10.1080/00268978000100141

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The exchange interaction between the two Ni atoms has been derived fromab initioHartree-Fock and CI calculations. Numerical values of the exchange integrals are presented for five internuclear distances. At large separations the interaction between two Ni atoms can be rationalized using a simple Heisenberg-Dirac-Van Vleck hamiltonian. The magnetic properties of a nickel crystal can not be explained by the signs of the exchange integrals alone.

ISSN:0026-8976    

DOI:10.1080/00268978000100151

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The Ornstein-Zernike (OZ) equation for a hard core lattice gas limited by a planar hard wall is solved by means of an iterative procedure. The treatment is based on the existing analogy between the OZ equation and the lattice Green function equation governing a random walk on the lattice. Results are shown, within the Percus-Yevick approximation, for the density profile, the pair correlations and the surface tension.

ISSN:0026-8976    

DOI:10.1080/00268978000100161

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

We have carried out a study, using the molecular dynamics simulation technique, of a simple model describing a chemical reaction in solution. The model consists of a three body reaction complex, in which a light particle transfers between two heavier species, surrounded by a ‘bath’ of 106 spherical liquid particles. Within the reaction complex we employ a three body potential with an effective barrier to transfer which depends strongly upon the separation of the heavy particles.

ISSN:0026-8976    

DOI:10.1080/00268978000100171

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A theory is presented about the effects of dielectric friction on the reorientation of a polar molecule undergoing rotational diffusion. In contrast to previous treatments, the torque on the molecular dipole is calculated in a way which accounts for the time dependence of the molecular orientations and is nevertheless consistent with the expression for the instantaneous reaction field. The results obtained permit an estimate to be made of the influence of dielectric friction on the values of the correlation times and on the frequency behaviour of the real and imaginary components of the complex permittivity.

ISSN:0026-8976    

DOI:10.1080/00268978000100181

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

It is indicated how Kramers' equation for the distribution function (in configuration-angular velocity space) underlying the motion of a pair of dipoles compelled to rotate about an axis through their common centre under the influence of their mutual dipole-dipole interaction may be derived. A solution procedure (analogous to that originally given by Brinkman in a discussion of translational brownian movement) for the equation is then set up, whereby the velocity-dependent portion of the distribution function is expressed in terms of two dimensional Hermite polynomials, whence a hierarchy of equations for the Laplace transform of the distribution function in configuration space is obtained. The lowest order approximation to the solution of the hierarchy is taken. This equation is then used to calculate the ensemble averages appropriate to the decay of electric polarization of an assembly of pairs of dipoles (rotating under the influence of their dipole-dipole interaction) following on the removal of a unidirectional electric field.

ISSN:0026-8976    

DOI:10.1080/00268978000100191

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The force and density origin of the ionic reaction process OH2+H+→OH3+is studied on the basis of the electrostatic force theory. In order to obtain reliable results, we have used the floating AO wavefunction (with minimal basis) which satisfies the Hellmann-Feynman theorem for the approaching proton. Accuracies of the results of the ordinary nuclear-centred AO wavefunction (with minimal basis plus polarization functions on hydrogen atoms) have been also examined. It is shown that the predominant origin of the driving force is the atomic dipole force which is caused by the transfer of the lone-pair density of OH2into the atomic region of H+and the succeeding inward polarization of the transferred electron density. The exchange force due to density accumulation in the forming O-H+bond region is of secondary importance. This is in contrast with the previous results for the radical reaction processes. The present reaction may be regarded as the transformation of the lone pair into the bond pair.

ISSN:0026-8976    

DOI:10.1080/00268978000100201

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The coherent neutron scattering intensities from five phonon modes in naphthalene have been measured at twenty four points in reciprocal space. These intensities are determined by a set of eigenvectors, and a fit to these intensities has been obtained by altering the eigenvectors iteratively. Significantly the best result has been obtained starting from eigenvectors derived from a model calculation, which were found to be close to the final result. This supports our method of assigning neutron scattering results by a comparison with model calculations.

ISSN:0026-8976    

DOI:10.1080/00268978000100211

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor