摘要:

The pseudo-potential method proposed by Burke and Chandra [10] is applied here to the study of e--CO scattering. The numerical problems associated with an efficient convergence of both the single-centre expanded orbitals (bound and continuum) and the multipolar expansion of the static interaction potential are discussed.

ISSN:0026-8976    

DOI:10.1080/00268977400101011

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The role of multipolar interactions in quenching free rotation in condensed phases is discussed, with particular attention paid to the HCl-SF6system. The magnitude of these interactions is shown to be closely correlated with the dielectric loss of the solvent, and to be sufficient to explain at least partially the variations of linewidth in the HCl rotational spectrum.

ISSN:0026-8976    

DOI:10.1080/00268977400101021

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The absorption and magnetic circular dichroism (MCD) spectra of a single crystal of [K(H2O)6][Al(Cr)(H2O)6](SO4)2, with an aluminium : chromium ratio of approximately 10 : 1, have been measured in the range 14 500–33 000 cm-1at various temperatures between 5 and 300 K. An analysis of the temperature dependence of the zeroth moment of absorption and first moment of MCD for the spin-allowed transitions4A2g→4T2gand4A2g→4aT1gshows that the vibrational modes responsible for the greater part of the absorption intensity are oft1usymmetry. The magnitude of the temperature-dependent contribution to the first MCD moment also indicates that the spin-orbit splitting of both4Tconfigurations is much smaller than expected, and possible origins of this phenomenon are discussed. The relatively large zeroth moments which dominate the MCD spectrum even at low temperatures are shown to arise from second-order interactions between the4A2gand4T2gstates. The spin-forbidden transitions4A2g→2aEgand4A2g→2aT2gexhibit complex vibronic fine structure, whose interpretation is discussed.

ISSN:0026-8976    

DOI:10.1080/00268977400101031

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The conformal solution approach is used to relate the distribution functionsgαβ(r) for a fluid mixture to those of a pure fluid,gx(r). The procedure is to expandgαβ(r) about the corresponding function for an ideal solution, usingσαβ3and εαβσαβ3as expansion parameters; the expansion of the functionyαβ(r) is also considered. Molecular dynamics results are reported for thetgαβfor argon-krypton liquid mixtures using the Lennard-Jones (12, 6) potential. These results are used to test the conformal solution expansions to first order; thegαβexpansion is found to be superior to that foryαβfor mostrvalues of interest. The second order term in the conformal solution expansion for the Helmholtz free energy is also calculated for argon-krypton mixtures, and found to be about 10 per cent of the value ofAEgiven by the van der Waals 1 theory.

ISSN:0026-8976    

DOI:10.1080/00268977400101041

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

SCF calculations employing the INDO approximation have been applied to a study of the interaction of water and the nitrobenzene radical anion in order to examine possible mechanisms by which electron spin resonance hyperfine coupling constants are altered when the solvent medium containing the radicals is changed from aprotic to hydroxylic. Calculations have been carried out for hydrogen-bonded radical-water complexes of nine different geometries. None of these calculations agree adequately with the available experimental data. Much better agreement with experiment is obtained if the hydrogen-bond formation is accompanied by a distortion of the nitro group toward a pyramidal conformation. The calculations indicate that this pyramidal distortion, rather than a rotation of the nitro group with respect to the aromatic plane, accompanies hydrogen-bond formation and suggests an experimental method of testing the prediction.

ISSN:0026-8976    

DOI:10.1080/00268977400101051

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A simple impulsive model of vibrational excitation by energy transfer collisions is described and applied to T-V, E-V and photodissociation processes. Intermolecular potentials are classified according to the sign of the model parameter,q, which is a decreasing function of energy. Whenq= 0 the model reduces to the spectator model. Positiveqpotentials (e.g. potentials of the Landau-Teller type) correspond to elongation of the BC bond as the atom A departs, while negativeqpotentials result in its compression. Negativeqpotentials should be typical of systems which are potentially reactive, i.e. where the ‘reaction path’ bends upwards. Negativeqpotentials lead to energy transfer in excess of the spectator limit. Near collinear orientations are found to favour T-V transfer whereas bent ones favour T-R transfer. A prescription for determining the distribution of final vibrational states is given.

ISSN:0026-8976    

DOI:10.1080/00268977400101061

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The theory is given for a model hamiltonian which combines the effects of large amplitude bending for a bent triatomic molecule with those arising from the coupling of vibrational, electronic and spin angular momenta characteristic of linear molecules. Two numerical examples are given for the application of the theory. (i) The vibronic and spin-orbit coupling between theÃ,2A1and[Xtilde],2B1states of PH2is discussed in detail in terms of the2Πustate of linear PH2with which they correlate. Thev2andKdependence of the doublet splitting in theÃstate is well represented in terms of a single spin coupling parameter for the2Πustate. (ii) The calculations give a quantitative account of the inversion for highv2of theK= 0 andK= 1 levels of the bentB2component of theã,3A2state of CS2arising from its correlation with a3Δ2ustate of linear CS2.

ISSN:0026-8976    

DOI:10.1080/00268977400101071

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

General expressions for the coefficients of theR-1multipole expansion of the third and fourth-order interaction energies are derived in (pseudo) spectral form for the interaction of two S-state atoms. Explicit accurate results, for the H(ls)-H(ls) interaction, are obtained for the lead O(R-11) third-order energy and the lead O(R-12) fourth-order energy by using one centre pseudo state methods. These calculations, together with the appropriate second-order results, furnish an accurate expression for the total long-range interaction energy through O(R-12) and illustrate the applicability of the pseudo state approach for the evaluation of high-order interaction energies.

ISSN:0026-8976    

DOI:10.1080/00268977400101081

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The low-temperature single-crystal spectrum of TMCBD has revealed a low-lying triplet state at 25 718 cm-1(72·5 kcal/mol). The observed band is ascribed to a3Au(3A2) ←1Agnπ* transition on the basis of its small singlet-triplet splitting, its polarization behaviour, and its vibrational structure. The3Austate is first-order spin-orbit coupled to either or both of the1B2uor1B3ustates. No evidence for two or more nπ* transitions was found. Several multi-membered progressions in the carbonyl wagging mode indicate the presence of a distorted excited state, in which the carbonyl carbons attain a pyramidal conformation. Analysis of the site symmetry shows that TMCBD is distorted to a boat-shapedC2vstructure in its triplet nπ* state.

ISSN:0026-8976    

DOI:10.1080/00268977400101091

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The additive interatomic interaction model has been used to calculate the thermodynamic functions of liquid water. The O … O and H … H nonbonded interactions were described by Kitaigorodsky potential functions of type 6-exp; for the H … O interactions the hydrogen bond potentials were introduced, and refined using sublimation heats of ice modifications and the normal vibrations of the water dimer. The thermodynamic functions of liquid water were obtained by averaging the corresponding thermodynamic quantities by the Monte Carlo method in the NVT ensemble. Different initial configurations were considered and the results were proved to converge, provided the Markov chain is sufficiently long. The calculated thermodynamic functions were in agreement with the experimental data. An analysis of instantaneous equilibrium configurations was carried out, and conclusions were drawn to what degree the previously proposed structures of liquid water correspond to reality.

ISSN:0026-8976    

DOI:10.1080/00268977400101101

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor