摘要:

A novel method is described for avoiding divergent contributions and delta function contributions in calculations involving singular potentials. The method was announced in a Preliminary Communication (1983,Molec. Phys.,48,1131); this paper presents the details of the method and extends it to angular problems. The method is illustrated by calculations of relativistic corrections in the hydrogen atom using the Foldy-Wouthuysen hamiltonian; the corrections are correctly calculated to ordermc2α8for the 1s1/2, 2P1/2and 2p3/2states and also to ordermc2α6for the 2s1/2state.

ISSN:0026-8976    

DOI:10.1080/00268978400102291

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The results of recording of the diode-laser spectrum of GeH4, having a natural distribution of isotopes, within the range 932·4-937·5 cm-1are presented. Taking into account the Coriolis interaction between (0100) and (0001) vibrational states, the rotational and centrifugal constants are obtained.

ISSN:0026-8976    

DOI:10.1080/00268978400102301

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The bound, metastable and virtual states of the van der Waals diatomics HeH, NeH, ArH, KrH and XeH have been calculated using recently determined potentials.

ISSN:0026-8976    

DOI:10.1080/00268978400102311

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The electronic structure of the dimers Cu2and Ag2and of their positive ions Cu2+and Ag2+is investigated byab initioLACO-MO-SCF calculations; to perform these computations the gaussian basis sets for transition metals recently proposed by Hyla-Krypsinet al., first contracted as suggested by the authors, then with other segmentation schemes, are used. A good description of molecular orbitals and other molecular properties is achieved. The results indicate also that medium-size basis sets can be successfully used in molecular computations, provided that the optimization is properly performed.

ISSN:0026-8976    

DOI:10.1080/00268978400102321

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The spin lattice relaxation times have been measured for all the deuterium nuclei in bromobenzene-d5dissolved in thermotropic nematic mixtures of EBBA and ZLI 1167. A Jeener-Broekaert pulse sequence was used. The spectral density functions evaluated for different compositions of the nematic mixture were related to the present theories of anisotropic tumbling molecules in anisotropic phases.

ISSN:0026-8976    

DOI:10.1080/00268978400102331

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The incoherent inelastic neutron scattering (IINS) spectrum of HCCo3(CO)9has been obtained in order to test some present methods of calculating band intensities for polycrystalline samples. The fundamental and first overtones of the carbon-hydrogen bending mode were observed at 860 and 1712 cm-1respectively. The C-H stretching mode was observed at 3041 cm-1and this is the first report of the observation of such a mode in which there is no possibility of confusion with overtone and combination bands.

ISSN:0026-8976    

DOI:10.1080/00268978400102341

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Proton multiple-quantum N.M.R. spectroscopy was used to investigate the anisotropic ordering in a magnetic field and molecular structure for the nematic phase of 4-cyano-4′-n-pentyl-d11-biphenyl (5CB-d11). The multiple-quantum spectra exhibit a greater resolution of line splittings than the conventional single-quantum Fourier transform N.M.R. spectrum of 5CB-d11. This greatly simplifies a spectral analysis for the proton dipole-dipole coupling constants. Splittings among the five-, six-, and seven-quantum spectra are used to obtain the biphenyl proton couplings for 5CB-d11. Two models for the biphenyl symmetry are considered in the analysis. In one model (D4symmetry), the two phenyl rings are assumed to be equivalent. In the other model (D2symmetry), the rings are inequivalent by virtue of structural or motional differences between them. Both models produce acceptable fits to the splittings assigned from the experimental spectra. However, we conclude that the spectra cannot be used to make a choice betweenD2andD4symmetry for the biphenyl group of 5CB-d11. The proton dipolar couplings obtained in both cases are used to derive values for internuclear distances and the biphenyl order parameters. TheD4symmetry dipolar couplings produce the most reasonable structural description of the biphenyl unit in which the phenyl ring geometry is close to that of benzene. The angle of twist between the ring planes is determined to be 30 ± 2°. The order parameters from theD4symmetry analysis are in good agreement with results reported by others for the same liquid crystal but with a higher degree of deuterium substitution. Possible causes for experimentally observed seven-quantum splittings that are not predicted by the symmetry model are discussed.

ISSN:0026-8976    

DOI:10.1080/00268978400102351

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

New conditions for the reference system in a generalized Andersen-Weeks-Chandler approximationy(12) =g(12) exp [βφ(12)] ≈y0(12) are derived which minimize an approximate free energy functional and lead to improved internal thermodynamic consistency for molecular fluids.

ISSN:0026-8976    

DOI:10.1080/00268978400102361

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Polarizations of the electronic transitions in metalloporphyrins were determined by polarized absorption measurements on poly(vinyl alcohol) films dyed with oxovanadium(IV) complexes of tetra(4-sulphophenyl)porphin being stretched in one direction within the plane of the polymer film. The stretching gives rise to a uniaxial orientational distribution of the disclike molecules. The E.S.R. spectra taken with the identical stretched films support the uniaxial distribution. The orientational distribution was determined by comparing the angular dependence of the observed E.S.R. line-shape with that calculated by a computer program developed for the numerical deconvolution of E.S.R. spectra of the partially ordered paramagnetic ensemble. The best fit distribution function was a long tailing function such as lorentzian rather than gaussian and could reasonably reproduce the optical polarization. The E.S.R. parameters of CuTPPS4were also evaluated by analysis of the complicated spectra of CuTPPS4observed partially oriented in the stretched PVA film.

ISSN:0026-8976    

DOI:10.1080/00268978400102371

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

A new Monte Carlo technique for the calculation of the functiony=gexp (βu) is proposed for hard body systems. The method is especially suitable at low and moderate densities and separations below the contact. They-function was calculated for hard spheres and hard diatomics. For hard spheres surprisingly small deviations from Grundke-Henderson formula were found. For the diatomics atLs = 0·6 radial slices at four special orientations were determined. The applicability of the proposed method and of the umbrella sampling technique due to Patey and Torrie are compared.

ISSN:0026-8976    

DOI:10.1080/00268978400102381

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor