High-frequency asymptotic behavior of the spectrum of the velocity autocorrelation function in a simple liquid

Abstract

The effect of short range forces of interparticle repulsion on the formation of high-frequency asymptotic behavior of the velocity autocorrelation function in a simple liquid is studied. For this purpose, a method is developed of a group expansion of the evolution operator of a many-particle system. It is shown that only irreducible pair collisions make a contribution to the high-frequency asymptotic behavior. As an illustration, calculations are performed for interatomic potentials modeled by a power function. Application of the developed methods to the case of classical high-temperature plasma leads to the well-known Ginzburg formula for the high frequency conductivity.