摘要:

The reaction operatorKis used to treat the collinear collision between an atom and a diatom in relative coordinates representation. With this choice of coordinates the coupling between the zeroth-order channels is due to a kinetic crossing term. The inadequacy of the channel functions to describe properly the asymptotic motion can be partially corrected by a renormalization procedure consisting of a shift of the energies. An analytical solution for arbitrary inter-continuum couplings can be given for theTmatrix when the diatom is approximated by a harmonic oscillator. Calculations are presented for two types of atom-diatom interaction potential : an exponential or a Morse function. The results are compared with the exact available numerical calculations and with the linearized distorted wave approximation. The treatment in relative coordinates with renormalization is found to yield, for many cases of physical significance, very good results.

ISSN:0026-8976    

DOI:10.1080/00268977600100021

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The He(I), He(II) and X-ray photoelectron spectra of iron tricarbonyl trimethylenemethane are reported, and these measurements, together with the bonding in the complex, are discussed with the aid ofab initioSCF MO calculations. The organic ligand is found to bear a net negative charge, and, as was found for other complexes, the position of the low energy photo-electron bands arising from the metal orbitals are inaccurately predicted using Koopmans' theorem.

ISSN:0026-8976    

DOI:10.1080/00268977600100031

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Catastrophe theory is applied to the asymptotic evaluation of integrals that occur in semiclassical collision theory with special reference to Thom's seven elementary catastrophes. It is shown how the topological structure of a family of classical trajectories can determine the caustics and canonical integrals of semiclassical collision theory. For the elementary catastrophes, the canonical integrals are of two types: one-dimensional cuspoids, and the two-dimensional umbilics which are non-separable in general. With the help of Morse's Lemma, the elementary catastrophes can also occur in the asymptotic evaluation of higher dimensional integrals. The uniform approximations are used to calculate the index of a catastrophe. The index is a measure of the order in ħ of a uniform approximation near a caustic. The hyperbolic umbilic is also used to discuss the validity of some semi-classical formulae currently used in the theory of atom-surface and atom-molecule collisions.

ISSN:0026-8976    

DOI:10.1080/00268977600100041

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The spin distribution andg-factors have been calculated for a number of dithiin cation radicals. Thes-spin densities on sulphur calculated by the open-shell unrestricted INDO method both with and without annihilation of the quartet component have been correlated satisfactorily with the observed33S hyperfine splittings. Theg-factors calculated according to the Stone theory by an open-shell restricted version of the INDO method are found in good agreement with observation; their deviation from the free-spin comes from the large spin density localized on the sulphur atoms and the small excitation energy from the ‘NB’ sulphur orbitals to the odd MO. Comparative calculations with thespandspdbasis sets demonstrate the modest effect of the 3d(S) orbitals on the considered physical constants of the dithiin cations.

ISSN:0026-8976    

DOI:10.1080/00268977600100051

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The vapour phase Raman spectra of the molecules F12CH3, F13CH3, H12CCl3, and H13CCl3have been recorded at pressures ofca. 1 atmosphere over the fundamental frequency regions. Partly resolved rotational structure is reported for some fundamentals of methyl fluoride. The Raman band contours of thee-species fundamentals have been analysed to yield Coriolis constants from whiche-species force constants have been calculated. The Coriolis and force constants so determined are compared with those based on analyses of appropriate vapour phase infra-red spectra.

ISSN:0026-8976    

DOI:10.1080/00268977600100061

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

A number of semi-empirical potentials are presented for benzene interactions that include both two-body and three-body effects. The two-body interaction gives accurate second virial coefficients for benzene vapour and when combined with a three-body term gives a good account of the static lattice energy and lattice parameters of the zero temperature crystal. A formula for the three-body quadrupole-induction energy is also derived.

ISSN:0026-8976    

DOI:10.1080/00268977600100071

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Semiclassical methods based on Einstein-Brillouin-Keller quantization and a classical variational principle are described. They are applied to model potentials of up to three coordinates and promise to be effective for the determination from potential surfaces of large numbers of vibrational energy levels of suitable polyatomic molecules at energies intermediate between equilibrium and dissociation.

ISSN:0026-8976    

DOI:10.1080/00268977600100081

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The apparently homogeneous E.S.R. spectra of solution manganous ions are interpreted in terms of a sum of degenerate lorentzian lineshapes with different widths. The existence of a distribution of linewidths instead of a single linewidth, is interpreted assuming that the electron spin relaxation is dominated by rotation of a static zero-field splitting tensor caused by slow configurational changes of the ionic environment, including first and second solvation spheres. Typical configurational lifetimes of the second solvation sphere were found to be τk∼ 10-9s. Details of the ionic structure and dynamics are discussed.

ISSN:0026-8976    

DOI:10.1080/00268977600100091

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

A vibronic theory of the Raman effect is developed within a semiclassical framework which provides explicit expressions for the symmetric and antisymmetric components of both the real and imaginary parts of the vibrational Raman transition tensor. The antisymmetric component of the real part is shown to originate in vibronic coupling and to vanish completely at transparent frequencies. Dispersion and absorption lineshape functions are introduced, and by allowing for interference between the α and β electronic absorption bands in ferrocytochromec, excitation profiles are derived for symmetric and antisymmetric resonance Raman scattering in this region which agree well with observation.

ISSN:0026-8976    

DOI:10.1080/00268977600100101

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The frequency-dependent polarizability of a molecule whose Hartree-Fock wavefunction can be written in terms of localized orbitals is shown to be the sum of bond and inner-shell orbital contributions. A variational procedure is used to find these contributions for the molecules methane, ethane, ethylene, acetylene, water and ammonia. Theoretical values of the refractive indices and Verdet constants for these molecules are obtained.

ISSN:0026-8976    

DOI:10.1080/00268977600100111

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor