摘要:

A Löwdin projected Slater determinant with different orbitals for different spin is an element of anf(S, N) dimensional space spanned by a set of linearly independent eigenfunctions of Ŝ2generated from the Slater determinant. A basis for this space is the set of valence-bond functions obtainable from the given Slater determinant. The decomposition of a projected determinant in terms of the valence-bond basis is determined for the singlet case. Possible applications of the decomposition are discussed.

ISSN:0026-8976    

DOI:10.1080/00268977000100941

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The immanant wavefunction, defined by Poshusta and Kramling [1], is obtained by symmetry projecting on a product ofN-independent orbitals | Φ> with certain (allowed) character operators of the permutation group. Energy bounds are determined for the immanant in terms of the energies of Goddard GI functions built from | Φ>. Finally we show that it is not feasible to calculate spin-dependent properties using the immanant.

ISSN:0026-8976    

DOI:10.1080/00268977000100951

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The OsCl62-ion survives long enough in the LiCl-KCl melt to be identified spectroscopically. The near infra-red band predicted by intermediate coupling appears at 5300 cm-1. Values of ζ5d= 3500 cm-1andK(4, 5) = 2150 cm-1are derived for the melt and with the 5060 cm-1band located for a KBr disk of Na2OsCl6, values of ζ5d= 3350 cm-1andK(4, 5) = 2150 cm-1are derived for crystals. From published susceptibility data and these parameters, an orbital reduction factor of 0·92 is estimated. The results are compared with those of Dorainet al. but the disparity is not resolved.

ISSN:0026-8976    

DOI:10.1080/00268977000100961

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Für symmetrische Kreisel mit einer dreizähligen Achse wird gezeigt, dass die Struktur einer Schwingungsbandevjund die einer zugehörigen hotbandvhgleich oder sehr ähnlich sind, und dass die Differenz (vj–vh) im wesentlichen durch Anharmonizitätskoeffizienten bestimmt wird. Es ist daher möglich fürvjdie Bandenkontur unter Einschluss von hotbands zu berechnen. Hierfür wird ein Rechenprogramm skizziert. Seine Anwendung auf 2v1von HCCl3und DCCl3sowie aufv1,v2,v3, undv4des NF3liefert einige Anharmonizitätskonstanten und αiAdieser Moleküle.

ISSN:0026-8976    

DOI:10.1080/00268977000100971

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The interaction between diatomic molecules at finite temperatures is analysed with respect to their translational, rotational and vibrational motion. At low temperatures quantum diffraction phenomena associated with these motions affect the intermolecular potential. These effects disappear when the temperature rises to high values compared to some characteristic temperatures found for each of the three types of motion. In this limit it is a reasonable approximation to consider the intermolecular potential as a suitable average over all possible configurations of the nuclei of the molecules.

ISSN:0026-8976    

DOI:10.1080/00268977000100981

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The E.S.R. and phosphorescence spectra of the lowest excited triplet states of some charge-transfer complexes containing phthalonitrile, isophthalonitrile and terephthalonitrile as electron acceptors have been measured. Hexamethylbenzene, pentamethylbenzene, durene and mesitylene were used as donors. From the observed zero-field splitting constants,D*, the charge-transfer degree,x, in the lowest excited triplet states of these complexes was obtained. For example,xfor the phthalonitrile-hexamethylbenzene complex is 0·48. For a fixed acceptor a decreasing order inxwas found to go with an increasing order in the ionization potential of the donor.

ISSN:0026-8976    

DOI:10.1080/00268977000100991

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The determination of expressions for derivatives of the SCF energy with regard to both linear and non-linear parameters in the LCAO formulation enables powerful minimization methods to be used to derive optimum values of these parameters.

ISSN:0026-8976    

DOI:10.1080/00268977000101001

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Semi-classical expressions for the elastic and reactive phase shifts for the double humped barrier characteristic of resonance tunnelling reactions are derived and their properties developed. The phase shifts are reduced to a Breit-Wigner resonance form by the application of two kinds of complex boundary conditions. The first boundary condition is the usual ‘outgoing waves only’ one, whilst the second is a ‘forward moving waves only’ boundary condition. This latter boundary condition gives rise to a novel form of complex energy:E=EnL+i(γnL/2) whereEnLis the resonance energy and the widthγnLmay be positive, negative or zero. The sign and magnitude ofγnLhave a natural interpretation in terms of the flux of particles through the two potential barriers that surround the dip in the activation barrier for the reaction.

ISSN:0026-8976    

DOI:10.1080/00268977000101011

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

High resolution E.S.R. spectra of a number of triarylmethyl radicals have been measured and interpreted. The observed meta and para-proton splitting constants conform to spin densities calculated according to McLachlan's formula. Ortho-protons show a systematic deviation which is ascribed to the influence of multiply excited states on the spin density distribution. Substituents have a very small influence on the spin density distribution, and this is explained with perturbation theory. In mono-para-substituted radicals the splitting constants of substituted and unsubstituted rings are identical whereas mono-meta-chlorine substituted triphenylmethyl probably has a slightly smaller angle of twist in the substituted than the unsubstituted ring. This is ascribed to the influence of the substituent on the moment of inertia of the aryl group. Finally the splitting constants of methyl protons are discussed in terms of hyperconjugation. It is shown that the fact that meta-methylproton splitting constants are relatively smaller than those of para-methylprotons must be ascribed to the influence of configuration interaction on the the π-electron spin density distribution.

ISSN:0026-8976    

DOI:10.1080/00268977000101021

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268977000101031

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor