摘要:

Relations between polynomial coefficients in the Taylor-series description of property surfaces are expressed in terms of Clebsch-Gordan (CG) series for the point group. Tables of CG coefficients are derived for the icosahedral group using a general projection matrix method, allowing counting and characterization of second derivatives of any property and third derivatives of the potential energy.

ISSN:0026-8976    

DOI:10.1080/00268978500103151

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The ground state argon-argon interaction is calculated using the supermolecular approach. Electron correlation effects are described by means of the many-body perturbation theory. A systematic sequence of even-tempered basis sets is used in conjunction with the function counterpoise technique used as a test, rather than a correction, for basis set superposition. 65 per cent of the interaction energy associated with electron correlation effects is recovered. 47 per cent of the van der Waals minimum is calculated. The magnitude of remaining errors is discussed.

ISSN:0026-8976    

DOI:10.1080/00268978500103161

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Zeeman levels of a trimeric cluster are obtained in the frameworks of a model, accounting for both the isotropic exchange and antisymmetric Dzyaloshinski-Moriya interactions. The field and angular dependences of the radio-frequency E.P.R.-transitions are calculated. The single crystal E.P.R. spectrum of trimeric clusters of transition metal ions are discussed in detail.

ISSN:0026-8976    

DOI:10.1080/00268978500103171

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A one-phonon spin-lattice relaxation theory is developed for trimeric exchange clusters. The spin-phonon coupling arises from the modulation of the isotropic exchange interaction by thermal lattice vibrations. Both the mechanisms of relaxation transitions and Van Vleck dipolar broadening give the same order contributions to the observed E.S.R. line widths of trimeric chromium(III) carboxylates.

ISSN:0026-8976    

DOI:10.1080/00268978500103181

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Pseudo-dipole oscillator strengths and excitation energies, which are discrete representations of original continuous dipole oscillator strength distributions (DOSDs), are tabulated for the ground state HF, HCl and HBr molecules and Ne, Ar, Kr and Xe atoms. These pseudo DOSDs are used to evaluate the dipole-dipole and triple-dipole dispersion energy constants for all possible two- and three-body interactions between HF, HCl, HBr, He, Ne, Ar, Kr and Xe. The importance of these results, and of the original DOSDs, is discussed briefly.

ISSN:0026-8976    

DOI:10.1080/00268978500103191

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A quasiclassical trajectory study has been carried out for collisions of4He with electronically excited H2(B1Σ+u) and its isotopomer HD. By using analytical fits for theab initiopotential energy surfaces of the ground and the excited state we have obtained vibrational and electronic quenching cross sections for several initial conditions. We draw the following conclusions. Vibrational excitation strongly promotes electronic quenching whereas translational energy is less effective. Rotational excitation decreases the rate of quenching. In a remarkable contrast to the ground electronic state, vibrational energy transfer on the excited potential energy surface is an efficient and fast process. Collisions at high energies results inT→Renergy transfer. The above conclusions are valid for both H2and HD.

ISSN:0026-8976    

DOI:10.1080/00268978500103201

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Deuterium N.M.R. has revealed pronounced variations in the orientational order along the alkyl chains which form an integral part of most mesogenic molecules. The model developed by Emsley, Luckhurst and Stockley to account for such variations is found to work reasonably well for the 4-n-alkyl-4′-cyanobiphenyls. However the agreement between theory and experiment can be improved considerably if the potential of mean torque for each conformer is modified to include contributions from the C-D bonds as well as the C-C bonds in the alkyl chains and from the aromatic core. Analysis of the observed order parameters for the C-D bonds in 4-n-pentyl and 4-n-octyl-4′-cyanobiphenyl allow the temperature dependences of the parameters in the potential of mean torque to be determined. The temperature variation of these parameters is found to be consistent with the predictions of molecular field theories of orientational order in mesogens composed of non-rigid molecules.

ISSN:0026-8976    

DOI:10.1080/00268978500103211

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The mechanical instability condition for the hard-sphere fluid is analysed by considering many different approximations to the direct correlation function. These have been obtained by adding to the truncated density expansion of the Percus-Yevick solution the contributions due to the 2nd and 3rd order parallel and bridge graphs. One finds that the bifurcation density values are smaller than the close-packing value (√2) and, depending on the truncation order, they vary in the range [0·97, 1·36].

ISSN:0026-8976    

DOI:10.1080/00268978500103221

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A method for analysis of the influence of electron correlation inside the rare earth ion and polarization of ligands on thef↔ftransition probabilities is presented. The approach is formulated by means of double perturbation theory and in terms of effective tensor operators. The detailed discussion of the structure of the third order contributions to the line strength is performed. The main attention is directed to the new term which represents both mechanisms simultaneously. The values of some third order contributions for [3P]0-[3H]4and [3P]0-[3F]4electric dipole transitions in Pr+3: LaCl3are calculated.

ISSN:0026-8976    

DOI:10.1080/00268978500103231

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Three luminescence transitions in the 476 nm excited spectrum of Cs2NaTmCl6between 7200–4100cm-1are assigned to the3H4→3F4,3H5and3F4→3H6transitions of TmCl3-6. A crystal field analysis of the energy levels of this anion is given.

ISSN:0026-8976    

DOI:10.1080/00268978500103241

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor