摘要:

The theory of Prigogine is applied to the deduction of a general kinetic equation for the singlet phase distribution for a fluid not in equilibrium. The intermolecular interaction is assumed to have the form of the sum of constituent pair forces; but the pair force itself is supposed to have a realistic form and any restriction to a hard-core repulsion is explicitly avoided. The general equation for the singlet distribution is set down in §5 and its derivation involves the consideration of the associated diagrams in numerical terms. The effects of the short-range (repulsive) and long-range (collective) molecular interactions are summed separately even although the hard-core repulsion of the pair potential is relaxed. The present paper is the natural extension of a previous communication by the present authors and of the earlier work of Rice and Allnatt.

ISSN:0026-8976    

DOI:10.1080/00268976800101451

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The method of Prigogine is used to construct an equation for the pair phase distribution of an insulating dense simple fluid not in equilibrium, on the basis of information about the corresponding singlet distribution developed in two earlier papers. Some preliminary numerical results derived from the equations of the theory are quoted.

ISSN:0026-8976    

DOI:10.1080/00268976800101461

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

It is shown that the configuration-space integrals required to evaluate diagrams appearing in the expansions of hard-sphere correlation functions in powers of the density can be considerably simplified. The simplification is achieved by introducing an approximation for the Fourier transform of a single hard sphere bond which is asymptotically exact for the product of a large number of Fourier transforms of topologically equivalent bonds. It is thus most suited for large diagrams which have relatively few interior diagonals. The four and five-sided Percus-Yevick diagrams are evaluated using this technique, and the results are compared with the exact P-Y computations wherever possible.

ISSN:0026-8976    

DOI:10.1080/00268976800101471

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Dans un article récent Levine et Birnbaum proposaient une étude théorique de la largeur spectrale de la partie dépolarisée du rayonnement Rayleigh diffusé par un gaz rare comprimé, attribuant la dépolarization aux modifications de polarisabilité de l'atome au cours d'un choc. Dans le cas de l'argon, nous avons montré que les fluctuations de champ interne permettent de rendre compte de cette dépolarisation et présentons un calcul de largeur spectrale attribuant la dépolarisation aux fluctuations de champ interne.

ISSN:0026-8976    

DOI:10.1080/00268976800101481

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Experimental values for1H and19F nuclear shielding anisotropies obtained from solid state, nematic phase, and molecular beam measurements are reviewed. Certain discrepancies are pointed out. An anisotropy operator is defined as a sum of two operators corresponding to the Lamb and high frequency terms. Approximations to the high frequency operator are given. Scales of absolute shielding constants are obtained, so that the magnitudes of the anisotropies can be discussed on the basis of non-empirical and semi-empirical calculations, and of the experimental results. The hypothesis due to Ramsey that the potential is constant for a given nucleus in different molecules is used to obtain approximate values for the Lamb term in the nuclear shielding constant.

ISSN:0026-8976    

DOI:10.1080/00268976800101491

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The theory of the rotation-internal rotation spectra for a rather general class of molecules with an internal rotor of the symmetryC2vis developed in the semi-rigid model approximation. Analytical expressions for the classical and quantum-mechanical hamiltonian are given. It is shown that the energy matrix may be analytically calculated in an appropriate zeroth-order basis composed of rotational and trigonometric wave functions. Symmetry properties of the hamiltonian are given and used extensively in factoring the energy matrix. The irreducible blocks of this matrix are of infinite order. The asymptotic behaviour of the matrix elements far from the diagnoal is shown to beO(ηn) (η< 1;nis the distance from the main diagonal), which is of decisive importance in the numerical diagonalization of such matrices.

ISSN:0026-8976    

DOI:10.1080/00268976800101501

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Wave functions possessing effective nuclear charges which are explicitly angularly dependent have been used as a simple minimal basis set for a one-centre study of HeH+. Correlation effects were introduced by using spatially different orbitals for electrons of opposite spin. Although the basis functions themselves are of considerable interest, the values obtained for the molecular energy and the theoretical bond length were somewhat disappointing.

ISSN:0026-8976    

DOI:10.1080/00268976800101511

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The semi-classical analysis of molecular orbiting collisions is discussed in the context of Breit-Wigner theory. The explicit introduction of a complex energy is used to characterize the quasi-stationary states in the dip of the effective potential characterizing the collision. Expressions for the resonance energies and widths of the quasi-stationary states are derived from the semi-classical wavefunctions and a formula given for the resonant contribution to the measurable total elastic cross section. The semi-classical wavefunctions are derived with the help of connection formulae based on an exact solution of the Schrödinger equation for a parabolic well and a parabolic barrier. The connection formulae for the case a parabolic well are derived and their properties developed.

ISSN:0026-8976    

DOI:10.1080/00268976800101521

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The N.M.R. spectra of meta dichloro and meta dibromo benzenes are analysed in the nematic phase of 4-methoxy benzylidene-4-amino-α-methyl cinnamic acid-n-propyl ester at room temperature.

ISSN:0026-8976    

DOI:10.1080/00268976800101531

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The effect of substituents on H-H geminal coupling constants is discussed, within the framework of the Pople-Santry MO theory of nuclear spin coupling, but along lines different from those of the earlier treatment of Pople and Bothner-By. Expressions have been obtained for the effect of electron lone-pairs and of vacant non-bonding orbitals, the results for the latter case being important for interpretation of the effect of β substitution. These calculations have also been extended in an attempt to interpret the effect of lone-pairs and substituents, respectively, on N-H and C-H geminal coupling constants for systems like H2C = N- and H2C = CX-.

ISSN:0026-8976    

DOI:10.1080/00268976800101541

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor