摘要:

Laser-excited fluorescence and thermal emission spectra, recorded at high resolution by Fourier-transform spectrometry, have been analysed to yield new information about the ground-state, X2Σ+, and six of the lowest-lying electronic states of BaF. In the present paper we give values of theeffectiveconstants for X2Σ+, A′2Δ, A2Π, B2Σ+, C2Π, D2Σ+and F2Π derived from an overall simultaneous fit to some 6470 lines assigned to rotational structure of 24 bands of 10 systems. Existing analyses are confirmed and extended, and a rotational analysis of levels of the state C2Π is given for the first time: the spin-orbit coupling constant in this state is found to increase unexpectedly rapidly with increasingv. The states A′2Δ, A2Π and B2Σ+interact strongly, and their mutual deperturbation, and the determination of their interaction constants form the subject of the following paper (Part II).

ISSN:0026-8976    

DOI:10.1080/00268979000101311

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This paper is concerned with the study of the 5d states, A′2Δ, A2Π and B2Σ+, (v= 0, 1, 2). It is shown that a complete interpretation of the spectra involving the 5d (v= 0, 1 and 2) states requires a 15 × 15 representation to take account of the spin-uncoupling interaction between A′2Δ5/2(v) andA′2Δ3/2(v+ 1). In the final analysis, the wavenumbers of the 4417 observed lines are fitted simultaneously and reporduced to within a standard deviation of 0·004 cm-1. Deperturbed energies and rotational constants for thev= 0, 1 and 2 levels of the 5d states are obtained. Values of the spin-orbit and rotational interaction constants within this group of 5d levels and of the spin-uncoupling constantsBΔ01andBΔ12are determined. The implications of the results for the nature of the binding in the 5d states are briefly discussed.

ISSN:0026-8976    

DOI:10.1080/00268979000101321

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An efficient perturbative method is developed to facilitate the treatment of the anharmonicity of bending degrees of freedom. The Rosen-Morse and sec2potentials are transformed so that perturbation theory may be applied easily. For a model problem it is found that the difference between the energy levels obtained from perturbation theory and the exact energy levels is less than 0·1 cm-1for the first six energy levels.

ISSN:0026-8976    

DOI:10.1080/00268979000101331

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The density-functional (DF) method is combined with the smoothed-density approximation to calculate the fluid structure in two-dimensional (2D) hard-disc (HD) systems. Density-dependent weighting functions in the DF method proposed by Tarazona for three-dimensional fluids have been applied to 2D systems for the calculation of the radial distribution function of HD fluids and the determination of the static structure of 2D HD fluids around the central hard triatomic molecule. The results compare reasonably well with Monte Carlo data. The radial distribution of a 2D Lennard-Jones fluid has also been calculated and shown to be in satisfactory agreement with Monte Carlo data except for the high-density fluid.

ISSN:0026-8976    

DOI:10.1080/00268979000101341

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Ideas underlying Enskog's kinetic theory combined with analysis of fluid dynamics in terms of binary collisions are used to derive a formula for the scattering function describing depolarized interaction-induced light scattering by moderately dense fluids at equilibrium. The new formula yields an exact expression for the integrated intensity. Numerical results obtained on the basis of the short-time version of the theory, valid for times of the order of one mean free time between collisions, agree well with molecular-dynamics simulations at moderate density.

ISSN:0026-8976    

DOI:10.1080/00268979000101351

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Two approximations are proposed for the triplet distribution function in classical fluids in the form of infinite series expansions. When used together with the second equation of the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy, the first approximation is shown to yield precisely the pair distribution function in the hypernetted-chain (HNC) approximation, while the second approximation gives the pair distribution function in the Percus-Yevick (PY) approximation. Both approximations are applied to non-equilibrium systems near equilibrium. As an example, application to the calculation of transport processes in electrolyte solutions is considered. The infinite series expansions are summed to give closed integral equations for the triplet distribution function that are related to the HNC and PY integral equations for the binary distribution function.

ISSN:0026-8976    

DOI:10.1080/00268979000101361

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The response potential of a small metallic sphere to a fluctuating dipole moment is determined from spherical-tensor theory. The non-local character of the electron response is included by using the random-phase approximation and by introducing a jellium model. The response field obtained from this calculation allows us to define a new expression of the effective linear polarisability of a molecule physisorbed on a metal particle. Two limiting cases are then considered: the dielectric approximation and the non-local homogeneous one.

ISSN:0026-8976    

DOI:10.1080/00268979000101371

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

We report large-scale MRD-CI calculations of the adiabatic and diabatic electronic energies, dipole and quadrupole electric moments, and first- and second-derivative vibronic couplings for the Ã2A1and [Btilde]2B2states of NH2in the region of their conical intersection. The diabatic representation has been obtained by transforming the adiabatic one under the condition that a quadrupole component has equal diagonal matrix elements in the diabatic basis. The transformation removes the singularities of the vibronic terms at the intersection locus and gives a smooth and small electronic coupling and negligible vibronic terms between the diabatic states.

ISSN:0026-8976    

DOI:10.1080/00268979000101381

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

We reportab initioMRD-CI calculations for the two lowest2A′ states ([Xtilde]2A1and Ã2B2) of the NO2molecule. A diabatic representation has been obtained by transforming the adiabatic CI wavefunctions in such a way that the resulting states have equal diagonal terms for the dipole moments perpendicular to the bisector of the bond angle. The method is tested for three different cross-sections of the potential-energy surfaces and is found to yield the desired small and constant coupling elements in the diabatic basis, even in the region of the conical intersection itself.

ISSN:0026-8976    

DOI:10.1080/00268979000101391

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The dependence of the spin-rotation hyperfine interaction on the vibration-rotation molecular state detected in the analysis of the hyperfine structures of thev3band of SF6can be taken into account by introducing some of the formal operators given by Michelot. We have established the relationships between the coefficients of Michelot's formal operators and the molecular constants. This has enabled us to understand how far the formal coefficients are independent and to check the order of magnitude of spectral effects due to other hyperfine operators described by Michelot.

ISSN:0026-8976    

DOI:10.1080/00268979000101411

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor