摘要:

The problem of calculating quantum corrections to the properties of a dense fluid whose molecules interact via pair potentials which are non-analytic functions of the intermolecular separation is studied. Expressions are given for the first and second quantum corrections to the free energy, and the first quantum correction to the radial distribution function. In the latter case it is important to include terms which, although negligible as far as thermodynamic properties are concerned, contribute significantly to the radial distribution function in regions near the potential singularities.

ISSN:0026-8976    

DOI:10.1080/00268977500101711

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Expressions derived in the previous paper for quantum corrections to the properties of a fluid are applied to the hard-sphere fluid. Numerical results are given for the first- and second-order corrections to the free energy and to the pressure, and for the first-order correction to the radial distribution function. Significant features are the large increase in quantum corrections with increasing density, and the qualitative difference that quantum mechanics makes to the radial distribution function near the hard core.

ISSN:0026-8976    

DOI:10.1080/00268977500101721

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

We study the interaction energy of a system ofNparticles with embedded point dipoles in a cube, this cube being duplicated indefinitely throughout space. We are able to evaluate exactly this energy for arbitrary positions and orientations of theNparticles, to provide an effective hamiltonian suitable for the study of the statistical mechanics of dipolar systems by both rigorous methods and computer simulation techniques. We describe methods for the rapid numerical evaluation of the hamiltonian and how it may be employed for the tasks outlined above.

ISSN:0026-8976    

DOI:10.1080/00268977500101731

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The lattice dynamics of crystalline tellurium has been studied using a valence force field in an attempt to describe the forces acting within the helical chains ; a central force field which extends to second nearest neighbours has been used for the inter-chain potential.

ISSN:0026-8976    

DOI:10.1080/00268977500101741

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The separated pair method, for systems containing even and odd numbers of electrons, is generalized by allowing for contributions from all available spin coupled states of the same total spin quantum numbersSandM. The total wavefunction is expressed as a linear combination of products of a given spin eigenfunction, which is constructed out of singlet and triplet coupled pairs, and a suitable spatial function built out of symmetric (for singlet) and antisymmetric (for triplet) spatial pair functions. The electron and spin density functions are then presented in a ‘ sum of pair ’ densities form, so enabling the effects of spin optimization on the chemical bonding to be interpreted in a simple and obvious way. Finally, a discussion is given of the practical application of the spin optimized separated pair method.

ISSN:0026-8976    

DOI:10.1080/00268977500101751

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Spin optimized pair wavefunctions, and their energies, are determined for the1A1ground state and the lowest energy3A1and3T2excited states of methane, and for the lowest energy3A1and2T2states of the methane positive ion. The spatial pair functions, in both bond orbital and separated pair forms, are expanded in terms of a limited basis set of orthogonalized gaussian fitted hydrogen and carbon hybrid atomic orbitals. The pair function coefficients for methane are not very sensitive to the symmetry and multiplicity of the electronic state; but significant deviations from the methane values, and a dependence on the nature of the electronic state, are observed for the methane positive ion. In all cases, the structure with the greatest number of singlet coupled pairs dominates the expansion of the total wave-function. The calculated ionization energies are in reasonable agreement with experiment, but the triplet excitation energies are poor.

ISSN:0026-8976    

DOI:10.1080/00268977500101761

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Thev20+v6±1andv5∓1+v6∓1perpendicular bands of methyl chloride have been studied under high resolution, and found to be coupled by a strongxyCoriolis interaction, with eventual level crossing. Evidence is given for theKnumbering of the branches and earlier assignments forv5∓1+v6∓1[1] are corrected. Several minor perturbations and unassigned lines remain to be clarified.

ISSN:0026-8976    

DOI:10.1080/00268977500101771

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The visible absorption spectrum and magnetic circular dichroism (MCD) spectrum have been measured for Cs2NaEuCl6at room temperature. The absorption spectrum and Zeeman splitting have been measured at liquid helium temperature as well. The Eu3+is in a site of six-coordinate octahedral symmetry. Transitions from the7F0(A1g) ground state and, thermally populated7F1(T1g) state to the5D0(A1g),5D1(T1g), and5D2(T2g+Eg) states have been observed. The fourth-order crystal-field parameter (B4) has been found to be 10–11 cm-1at both temperatures. A rich vibrational structure was seen on the two electric diple-allowed transitions and an assignment of the observed vibrations made. At liquid helium temperature thegvalues of the5D1(T1g) and5D2(T2g) states were found to be 1·5±0·15 and 1·5±0·5, respectively.

ISSN:0026-8976    

DOI:10.1080/00268977500101781

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

On analyse les profils des bandes de diffusion dépolarisée Raman et Rayleigh du dioxyde de carbone liquide, obtenus à 100, 1500 et 3000 atmosphères. L'utilisation des moments de ces bandes et des fonctions de corrélation calculées par transformation de Fourier, permet de comparer les résultats expérimentaux avec les théories proposées par Gordon et Litovitz pour rendre compte de la dynamique moléculaire à l'état liquide. On montre que les profils de diffusion dépolarisée Raman associés à une transition Σg+ont, essentiellement pour origine, la réorientation monomoléculaire de CO2quelle que soit la pression exercée, tandis que la diffusion Rayleigh dépolarisée est influencée à la fois par les dynamiques monomoléculaire et multimoléculaire; l'aspect coopératif des mouvements augmentant avec la pression.

ISSN:0026-8976    

DOI:10.1080/00268977500101791

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The classification of terms of the vibration-rotation hamiltonian according to the order of magnitude of coefficients occurring in them is used as an organizational device for the contact transformation method. The relation between order of perturbation in Rayleigh-Schrödinger theory and the formal expression of the contact transformation is also discussed.

ISSN:0026-8976    

DOI:10.1080/00268977500101801

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor