Accession Number : AD0696945

Title :   ON THE FREE-VOLUME MODEL OF THE LIQUID-GLASS TRANSITION.

Descriptive Note : Technical rept.,

Corporate Author : HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS

Personal Author(s) : Turnbull,David ; Cohen,Morrel H.

Report Date : SEP 1969

Pagination or Media Count : 20

Abstract : We have improved the free volume model for molecular transport in dense fluids by taking account of the variable magnitude of the diffusive displacement. The development is carried through in a way which may display more clearly the relation between the free volume model and the Enskog theory. Molecular dynamics computations have shown that the self-diffusion coefficient in the hard sphere fluid at the highest densities is falling precipitously, with increasing density, away from the Enskog values. It appears that this density trend, which was attributed to back scattering, if continued, would lead to a continuous solidification. It is shown that the magnitude and density trend of this deviation are described satisfactorily by the free volume expression, where the free volume is referred to the specific volume of the Bernal glass. We conclude that at least the molecular transport manifestation of a liquid-glass transition can be deduced entirely within the framework of the van der Waals physical model for liquids with due corrections for the variation of the effective hard core radius with temperature. The free volume model results from a crude, but physically plausible, approach to this problem. (Author)

Descriptors :   (*GLASS, PHASE STUDIES), DIFFUSION, TRANSPORT PROPERTIES, MOLECULAR ASSOCIATION, LIQUIDS

Subject Categories : Ceramics, Refractories and Glass
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE