摘要:

The six lowestσ-bonded potential surfaces for the reaction K+NaCl=KCl+Na have been calculated on a semi-empirical model with a single valence electron in the field of the three closed shell ions. A simple method is proposed by which the energetic effects of valence-core orthogonalization, which are of crucial importance in the calculations, may be included in the potentials of the ions. Test calculations on the ions Na2+and K2+are in good agreement with experiment.

ISSN:0026-8976    

DOI:10.1080/00268976800100011

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The previously developed theory of separated electronic groups is applied. The configuration interaction of closed and mixed open and closed shells is considered. Explicit expressions for interaction operators between electrons belonging to different groups and the corresponding matrix elements are given in both cases.

ISSN:0026-8976    

DOI:10.1080/00268976800100021

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Usually, many-electron wave-functions for molecules are constructed from antisymmetrized products of one-electron orbitals. Configuration interaction and energy level calculations are based on variational principles, and matrix elements are obtained using Slater's rules. In this paper this method is generalized, the orbitals being replaced by group functions, each one describing any number of electrons.

ISSN:0026-8976    

DOI:10.1080/00268976800100031

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

This is the first part of a work of systematic studies of molecular vibrations of various models. Some conventions are proposed as to the orientations of cartesian axes and degenerate symmetry coordinates, in addition to already existing (but not universally adopted) conventions. Symmetry coordinates are specified in the present part for a number of three-atomic and four-atomic molecular models. The corresponding symmetrizedGandCαmatrix elements have been worked out and are available on request to one of the authors (S. J. C.).

ISSN:0026-8976    

DOI:10.1080/00268976800100041

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The electric quadrupole moment of a dipolar molecule depends upon the molecular origin from which it is measured. An electro-optical method has been successfully used for measuring the quadrupole moments of non-dipolar molecules, and the question arises: when the same method is applied to a dipolar substance what is the molecular origin to which the measured quadrupole moment should be referred? It is shown that this origin is not the centre of mass, but another point which may be called the ‘effective quadrupole centre’, the position of which depends in general on the wavelength of the light. Dipolar molecules experience a force in the field gradient and this enhances the contribution to the refractive index anisotropy from molecules which are out of line with the detector but in the light beam. This contribution is proportional to the dipole moment and is origin-dependent; it vanishes if the effective quadrupole centre is chosen as the origin. It is concluded that the electro-optical experiment should give identical quadrupoles for isotopically distinct species, and that the results for dipolar molecules may show an apparent dependence on the frequency of the light. The effects of distortion of the molecule by the field gradient are also considered.

ISSN:0026-8976    

DOI:10.1080/00268976800100051

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The pure quadrupole resonance spectra for the14N nucleus in five-membered heterocycles is reported and interpreted in terms of the electron distribution around the nitrogen atom in these compounds. Although reasonable agreement with the predictions of simple molecular orbital theory is obtained, the calculated electron distributions are very sensitive to the assumptions made concerning the hybridization of the sigma orbital framework.

ISSN:0026-8976    

DOI:10.1080/00268976800100061

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The measurements of14N pure quadrupole resonance spectra of symmetrical azabenzenes and their analysis in terms of the electron distribution around the nitrogen atom has been extended to the two asymmetric diazabenzenes, pyrimidine and pyridazine, and to a variety of substituted pyridines. The coupling constants of unsymmetric compounds, i.e. compounds where the two nitrogen sigma bonds are not equivalent, cannot be analysed completely but yield values of the difference between the pi population and the average sigma population, including the lone-pair. Within these limits the electron distributions are in good agreement with those expected from simple molecular orbital theory. The results for the substituted pyridines show very strikingly the expected effect of substituents and the expected differences between the same substituent eitherorthoorparato the nitrogen atom on the one hand ormetaon the other.

ISSN:0026-8976    

DOI:10.1080/00268976800100071

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The14N quadrupole coupling constants of a number of saturated organic nitriles have been determined by pure quadrupole resonance spectroscopy. The significance of these results together with those previously obtained for the nitrile group to the problem of long-range interactions in saturated molecules is discussed and it is shown that such interactions can for this system be at least as important as those produced by the more familiar conjugation.

ISSN:0026-8976    

DOI:10.1080/00268976800100081

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268976800100091

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor