摘要:

The spectrum of (HF)2was recorded under equilibrium conditions in a long path thermostated cell at a resolution of 0·02 cm-1between 350 and 550 cm-1.

ISSN:0026-8976    

DOI:10.1080/00268978700102771

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The depolarized Raman spectrum of xenon at low temperature of 193K is reported. The contributions of the bound dimers in the pure rotation and vibration rotation region are enhanced at this low temperature. The experimental profile is compared with the quantum mechanical calculation using different models of the interaction polarizability anisotropy. The BWLSL X2 potential and DID with hyperpolarizability correction gives extremely good agreement with experiment.

ISSN:0026-8976    

DOI:10.1080/00268978700102781

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

It has been observed that for a computer-simulated Lennard-Jones 12-6 liquid on the liquid-vapour coexistence line, the distribution function,p(f), for a cartesian component of the force on an atom,f, is remarkably close to exponential in form over a wide range off. There appears to be no simple theoretical reason for this simple result. An approximate theoretical analysis is given which confirms this behaviour and suggests that it may be quite general for liquids with approximately spherically symmetric, short-ranged, interparticle potentials.

ISSN:0026-8976    

DOI:10.1080/00268978700102791

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Results are given for the properties of the trajectories of atoms in a simulated Lennard-Jones 12-6 liquid at three states on the coexistence line. The trajectories are analysed by Richardson's method [1]. It is shown that the trajectories have a substantially different fractal behaviour even for these three states of this particular liquid. This is contrary to the recent assertion [7] that the finite-fractal properties of liquids have a ‘universal’ behaviour. However there may be ‘universality’ in a more limited sense for a certain function,f(ϵ), which was introduced elsewhere [8] and is used here to analyse the data. A satisfactory theory of the fractal properties of even this the simplest realistic liquid is still lacking.

ISSN:0026-8976    

DOI:10.1080/00268978700102801

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

New working expressions are given for the first derivatives or elementary sensitivity coefficients of reactive and non-reactive scattering matrices with respect to an arbitrary input parameter. The expressions, as in an earlier paper, are constructed for collinear reaction but within now a less restricted representation of the electronic-vibrational degrees of freedom. Application is made to two simple test problems. The first deals with the collision energy dependence of transmission and reflection on a one dimensional potential curve. We examine the relative convergence behavior of values and energy derivatives of the scattering elements with the steplength in our procedure for integrating the dynamical equations, and find that errors in the sensitivity coefficients are sometimes larger and sometimes smaller than those in the corresponding scattering elements. The second test problem adds on a closed potential curve which is non-adiabatically coupled to the potential curve of the first (test problem). We examine the effectiveness of sensitivity and non-sensitivity calculations in describing how the scattering elements behave through the space of a parameter which centers the non-adiabatic coupling envelope. Our findings are drawn into the following concluding statement (of the application section) that: for the single parameter variation, sensitivity and half-spaced non-sensitivity calculations using a common steplength, yield essentially equal quality descriptions of the parameter dependence. When this conclusion is projected into a multi-parametric context and we roughly estimate the relative work involved in the two approaches, a minimum order for the parameter space, i.e. 2, is identified such that the sensitivity approach may be expected to be the more efficient.

ISSN:0026-8976    

DOI:10.1080/00268978700102811

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Monte Carlo computer simulations of hard spherocylinder fluids have been used to study a representation of the pair distribution function of non-spherical molecules in which the separation variable is a function of the relative orientation of the molecules. This approach was introduced by Kabadi and Steele in an investigation of molecules interacting through a gaussian overlap potential model, and it was found that spherical harmonic expansions of this pdf had greatly improved convergence properties. Similarly good convergence is found also for hard spherocylinders and the method offers the possibility of providing a reliable, accurate and economical representation of the structure of such fluids.

ISSN:0026-8976    

DOI:10.1080/00268978700102821

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

SO2/H2O pressure broadening and frequency shifting coefficients, γ0and δ0, are reported for 23 unblended absorption lines in the infrared vibration-rotation bandv2of H2O between 1400 and 1800cm-1. The data were obtained from FTIR spectra recorded with a resolution of 0·03cm-1. Values for γ0and δ0are found to lie between 0·6 and 0·1cm-1atm-1and +0·10 and -0·13cm-1atm-1, respectively.

ISSN:0026-8976    

DOI:10.1080/00268978700102831

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The colloid-colloid structure factor is calculated for polystyrene colloid solutions on the basis of the charged-hard-sphere (CHS) model in the rescaled-mean-spherical-approximation (RMSA). It is shown that the characteristic features of the experimental structure factors can be well reproduced by a binary CHS system for a salt free solution and by a quaternary CHS system for the solution with added salt. The physical meanings of the large effective hardsphere diameter and the reduced effective charge obtained by the rescaling procedure are discussed.

ISSN:0026-8976    

DOI:10.1080/00268978700102841

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The crystal structure of sulphur hexafluoride in its low temperature phase has been solved from neutron powder diffraction measurements. At both 23 K and 85 K the structure is triclinic, space groupP1, withZ= 3. It is in good agreement with the structure predicted previously by molecular dynamics simulations. No evidence was found for the existence of an hexagonal phase. The phase transition is interpreted in terms of two separate lattice distortions from the cubic, high temperature phase which couple to different stages of orientational ordering. The mechanism driving the transition is the resolution of orientational frustration as the temperature is reduced. The present results confirm the validity of the simple intermolecular force model employed in the simulations for SF6and they have been used to improve the parameters of this model.

ISSN:0026-8976    

DOI:10.1080/00268978700102851

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Thermodynamic properties for several binary mixtures of atomic fluids are predicted from perturbation theories using the hard-sphere reference. These calculations differ from previous studies in that the hard-sphere mixture properties are computed more accurately and a new criterion is proposed and tested for determining the hard-sphere diameters. Comparisons with computer simulation results and with experimental data show the theory to be highly accurate.

ISSN:0026-8976    

DOI:10.1080/00268978700102861

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor