摘要:

A counter-example is produced to show that Altmann's representation of the groupSof a non-rigid molecule as a semi-direct product of an ‘isodynamic’ groupIand a point groupGin the formS=I ^ Gdoes not always hold in the Longuet-Higgins classification scheme. Altmann's proof of this relation requires reconsideration. However, the discrepancies between the two treatments in the case of boron trimethyl are due to Altmann's use of an operation of questionable validity called a ‘flip’, denoted byZ2I.

ISSN:0026-8976    

DOI:10.1080/00268977100101771

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The author's proposed expression for the groupsSof a non-rigid molecule as a semi-direct product of the isodynamic groupIwith a point groupG,S=I ^ G, is queried in the preceding paper by Watson by means of a discussion of the molecule of orthoformic acid. However, Watson's interpretation of the groupGis not the one required in Altmann's method for the semi-direct product to hold.

ISSN:0026-8976    

DOI:10.1080/00268977100101781

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The Schrödinger equation for the system H+-H developed in a previous paper is considered using new expansion functions for electronic states obtained from H2+molecular ion electronic eigenfunctions by a unitary transformation. These new functions have the advantage of remaining orthonormal at all internuclear separations and asymptotically becoming symmetrized atomic hydrogen states. Although they are eigenfunctions of the H2+hamiltonian only in the limit of large internuclear distance, the effect of the H2+hamiltonian on these functions is readily found.

ISSN:0026-8976    

DOI:10.1080/00268977100101791

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Cet article concerne l'utilisation des quasi-moments ˆπm, définis par

ISSN:0026-8976    

DOI:10.1080/00268977100101801

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

A model hamiltonian which describes the non-reactive collision of two non-linear molecules has been constructed. This hamiltonian gives insight into the character of the complex translational, vibrational and rotational motions. The main features of the isolated molecule case are essentially disturbed by the non-adiabatic interaction between the macroscopic molecular motions and the vibrations. The usual angular momentum expressions are found to be the asymptotic limits of the true angular momenta in the case when these non-adiabaticities are switched off.

ISSN:0026-8976    

DOI:10.1080/00268977100101811

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Thermodynamic properties of liquid argon are calculated by Monte Carlo and molecular dynamics techniques, using accurate pair-potential functions determined from the properties of solid and gaseous argon, together with the Axilrod-Teller three-body interaction. Satisfactory techniques for evaluating three-body contributions to thermodynamic properties without excessive requirements of computer time are described. Quantum corrections are included. Agreement with experiment is excellent: the best pair and triplet potentials give an excellent description of the properties of solid, gaseous and liquid argon.

ISSN:0026-8976    

DOI:10.1080/00268977100101821

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Zwanzig's projected kinetic equation is rederived by a perturbation method. A choice of projection is proposed which, in conjunction with appropriate initial-value conditions, yields kinetic equations for the two time distribution functions of phase subsets for a system in equilibrium. These equations are generalizations of the Fokker-Planck equations in which the dissipative terms are non-Markoffian.

ISSN:0026-8976    

DOI:10.1080/00268977100101831

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The line shapes of a triplet spin system which interacts simultaneously with the molecular environment and with an externally applied field depend on the relative strengths of these interactions and on the motion of the molecule relative to the laboratory. In this paper line shapes are reported for zero, low, intermediate and strong applied fields, assuming that the molecular motion is due to strong collisions and that the tumbling rate is slow or intermediate.

ISSN:0026-8976    

DOI:10.1080/00268977100101841

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The question of the statistical consequences of cooperative hydrogen bonding in water is examined. Methods familiar in the theory of ferromagnetism are employed to deduce the most probable spatial configurations resulting from a simple mathematical model for the cooperative nature of the hydrogen bond, of the type suggested by Frank and Wen. Contrary to the conclusions of these authors, this so-called significant structure turns out to be an extensive bond network, interrupted by regions containing relatively few bonds, the exact converse of that originally conjectured by these two authors in their famous flickering cluster hypothesis.

ISSN:0026-8976    

DOI:10.1080/00268977100101851

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Non-adiabatic transitions in two-level systems are investigated theoretically for a random time dependence of ħω, the energy difference, between the levels. We assumed that ω = ω(x) and the coordinatex=x(t) is a random function of time. Diffusion and Poisson processes (both homogeneous and with a source) forx(t) were assumed. The cases of linear crossing terms (ω = γx) and non-linear terms (ω = ωeexp (- αx) + ω0) were considered. Values of the non-adiabatic transition probability per unit time were obtained by perturbation theory for ω1τc≪ 1 where τcis the correlation time and ω1is the off-diagonal matrix element.

ISSN:0026-8976    

DOI:10.1080/00268977100101861

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor