Effect of attractive interactions on tagged particle dynamics

Abstract

We study tagged particle dynamics in a one-component simple liquid characterized by the Lennard-Jones (LJ) interaction potential. Extended mode coupling theory is used to obtain the correlation function which feeds back on the dynamics of the self-correlations. The cooperative dynamical effects are studied by evaluating various properties of tagged particle motion as influenced by the collective dynamics. Comparison between the results obtained for particles with purely repulsive interactions like the truncated LJ potential (or the hard-sphere interaction) and that of the full LJ potential are shown. The nature of the velocity autocorrelation function and the non-Gaussian variation of the van Hove self-correlation function is specifically highlighted here. The role of static structural input in the theory is considered especially in this regard.