The velocity autocorrelation function of nanoparticles in a hard-sphere molecular system

The diffusion of nanoparticles in a dense molecular medium representing a fluid (liquid or gas) composed of hard absolutely elastic spheres was studied by the molecular dynamics method in a broad range of the medium density. It was established that relaxation of the velocity autocorrelation function of the particles is well described by a superposition of two exponents with different characteristic relaxation times. Dependence of the velocity autocorrelation function on the particle and radius and on the carrying fluid density was studied.