Translational and rotational diffusion in liquids. II. Orientational singlehyphen;particle correlation functions

摘要

This is the second of two articles concerned with the translational and rotational motion in molecular liquids. In this paper, orientational singlehyphen;particle correlation functions are considered. By applying the approximations developed in Paper I of this series, Gordon'sJdiffusion model theory is derived. The analysis does not require one to adopt the unrealistic views of the liquid state that are usually attributed to that theory. The range of validity of theJdiffusion model approximation is ascertained. Further, a microscopic expression is derived for the relaxation time which Gordon introduced phenomenologically. The expression leads naturally to a simple method for calculating tgr;J. These predictions are tested against results obtained from recent computer simulations of liquid N2. The comparison shows that the theory is qualitatively accurate.