Abstract: The parameters for a representative two-body Morse potential are determined for the solidified inert gases by fitting to 0 degrees K solid data. This is done using first the harmonic approximation and subsequently the first-order self-consistent harmonic approximation, to describe the solid at 0 degrees K. On comparing the two cases, the effect on the potential of neglecting anharmonicity is found to be insignificant for xenon and krypton, small for argon but most important for neon. For neon, dispersion curves are calculated using the potentials found in the two cases and other Lennard-Jones potentials determined using various solid models to fit the 0 degrees K properties. The effect of the potential changes on the dispersion curve is marked.

Abstract: A quantum-mechanical variational technique is applied to an Einstein model of a solid, and the heats of sublimation and equations of state of solid Ne, A, Kr, and Xe are calculated at 0°K. Mie-Lennard-Jones 6-12 potentials appropriate to the gas-phase data are used throughout, and the importance of quantum-mechanical effects is discussed; in general, good agreement with experiment is obtained. From the theoretical zero-point energies equivalent Debye temperatures, θ, are calculated, and from the dependence of these θ on volume, Grüneisen constants are computed in good agreement with experiment. Theoretical compressibility curves (at 0°K) are presented, and compared with the available experimental data; in the case of Ne, the only substance for which high-pressure data are available, the agreement is rather good up to 20 k atmos.

Abstract: A set of combining rules for intermolecular pair potentials recently formulated and shown to be satisfactory for both the Lennard-Jones (12-6) potential and the Morse potential is applied to the exp 6 potential. Examination of the transport properties of the noble gas systems indicates that the same combining rules are also satisfacory for the exp 6 potential and, in fact, superior to the other combining rules previously suggested for the exp 6 potential model.

Abstract: A reanalysis of the transport and equilibrium properties of simple gases was performed in order to obtain more reliable parameter values for two models describing the interatomic potential, the Lennard-Jones (12-6) model and the (exp-6) model. New parameter values for the like interactions were derived from recent accurate viscosity measurements, with an exception for helium. The parameter values for the (exp-6) model differ considerably from the commonly used values given by Mason. The description of the transport properties of neon, argon, krypton and xenon is in general improved with these new parameter values. However, the description of the second virial coefficient of the considered gases with the parameter values from transport properties is rather poor. The parameter values for the unlike interactions could be calculated with several combination rules, confirming the results obtained from recent diffusion measurements in noble-gas mixtures.