摘要:

The radial distribution function can be expressed in a virial expansion. Using the 6 : 12 potential the second-order density coefficient,g2(r), is numerically calculated for a wide range of temperatures and intermolecular separations. These results are used to calculate the second-order density coefficient,c2(r), in the expansion of the direct correlation function and to calculate the fourth virial coefficient,B4. In addition, approximate results forg2(r),c2(r), andB4are calculated on the basis of the Percus-Yevick, hypernetted chain, and the self-consistent approximations of Hurst and Rowlinson. These approximate results are compared with the exact results. The Percus-Yevick theory is in good agreement with the exact results at high temperatures but is unsatisfactory at low temperatures. The hyper-netted-chain approximation is in fair agreement with the exact results at high temperatures, is in poor agreement at intermediate temperatures, but is in good agreement at low temperatures. The self-consistent approximations are in reasonably good agreement with the exact calculations at all temperatures.

ISSN:0026-8976    

DOI:10.1080/00268976600100541

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

High explosives have been used to shock liquid hydrogen to 39 500 bars, 5·2 cm3/g and an estimated temperature of 1100°k from an initial state near the normal boiling point, 20·5°k and 14·1 cm3/g. How far the melting curve and the equation of state can be pursued by shock wave experiments is discussed. The derived intermolecular potential between two hydrogen molecules is shown to be inadequately represented by the previously postulated Lennard-Jones 6–12 potential in the repulsive region between 2·0 and 2·7 Å. The power of the inverse intermolecular distance is shown instead to be 8·5 in that region if a purely repulsive potential is used.

ISSN:0026-8976    

DOI:10.1080/00268976600100551

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The method described previously for the calculation of theXspectrum for spin systems of of theXnAA′Xn′type is extended by means of magnetic equivalence factoring to cases in which the long-range coupling constantJxis non-zero. This coupling is treated as a first-order perturbation to the energy levels obtained whenJx=0, and it is found thatJxmay be measured directly from the separations between easily identified lines in the spectrum. A detailed account of theX3AA′X3′ system is given, and the N.M.R. spectrum of fluoro-N,N′-dimethyl-1,3,2,4-diazadiphosphetidine is analysed. The spectral parameters obtained are discussed. A computer programme which calculates the spectra of systems involving magnetic equivalence is used to examine the validity of the approximations in the method.

ISSN:0026-8976    

DOI:10.1080/00268976600100561

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The proton spin-lattice relaxation time has been measured at 20·8 Mc/s for a series of solutions of water in heavy water and solutions of ammonia in heavy ammonia for the temperature range from the melting point to the liquid-vapour critical temperature. Measurements have also been made for water over limited temperature ranges at several fixed densities.

ISSN:0026-8976    

DOI:10.1080/00268976600100571

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

From the infra-red spectral data for gaseous difluoramine (NHF2), and difluoroamine-d(NDF2), a set of quadratic valence potential energy constants has been obtained. The constants for the N-H and N-F stretchings are respectively 5·6474 and 4·0681 mdyn/Å. These values are somewhat less than the corresponding values for NH3and NF3and are consistent with slightly longer N-H and N-F distances in difluoroamine.

ISSN:0026-8976    

DOI:10.1080/00268976600100581

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The frequency dependence of the nuclear relaxation times in solutions containing free radicals, previously determined by Gutowsky and Tai, has been re-interpreted in terms of the relaxation theory due to Hubbard. The good agreement between theory and experiment confirms the conclusions of other workers that, for protonic systems, the major contribution to the relaxation mechanism is from dipolar electron-nuclear coupling modulated by translational diffusion. In aromatic fluorine compounds, however, asscalar coupling is also evident. Although Hubbard's diffusion model gives an adequate description of the relaxation in these systems, it may not be entirely satisfactory over a larger range of magnetic field strengths.

ISSN:0026-8976    

DOI:10.1080/00268976600100591

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

In the case of very large frequency of periodic motion, the spectrum of a molecule is identical with the spectrum of a fixed system described by the average Hamiltonian; theoretical proof of this well-known fact is presented and the conditions necessary are defined.

ISSN:0026-8976    

DOI:10.1080/00268976600100601

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

Starting from some previously derived results, general closed-form expressions are given for the total number of configurations or structures, the number of configurations of a particular multiplicity, and the total number of antisymmetrized product functions (AP's), in anN-electron system. The number of electrons may be even or odd, and the number of orbitals may assume any value larger than 1/2N- 1 or 1/2(N- 1) in theN= even andN= odd cases, respectively. Some special cases are mentioned in which the formulae become particularly simple. The results are derived in view of comparing molecular orbital and valence bond calculations on actual molecules when both methods are used in their many-configuration aspect.

ISSN:0026-8976    

DOI:10.1080/00268976600100611

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

摘要:

The influence of the symmetry species of the normal modes of vibration of a molecular ion on its dissociation processes is studied. The transformation of a normal mode into a reaction coordinate is made easier if certain symmetry conditions are verified. Several applications are proposed.

ISSN:0026-8976    

DOI:10.1080/00268976600100621

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268976600100631

出版商:Taylor & Francis Group    

年代:1966

数据来源: Taylor