Diffusive Dynamics of Binary Lennard-Jones Liquid in the Presence of Gold Nanoparticle: A Mode Coupling Theory Analysis

Abstract

Molecular dynamics simulation has been performed to analyze the effect of the presence of gold nanoparticle on dynamics of Kob-Anderson binary Lennard-Jones mixture upon supercooling within the framework of the mode coupling theory of the dynamic glass transition. The presence of gold nanoparticle has a direct effect on the liquid structure and causes the peaks of the radial distribution functions to become shorter with respect to the bulk binary Lennard-Jones liquid. It is found that the dynamics of the liquid at a given density is consistent with the mode coupling theory (MCT) predictions. In accordance with the idealized MCT, the diffusion constants D(T) show power-law behavior at low temperatures for both types of binary Lennard-Jones (BLJ) particles as well as the 13 gold atoms comprising the nanoparticle. The mode coupling crossover temperature Tc is the same for all particle types, however, Tc = 0.4 is reduced with respect to that of the bulk BLJ liquid and the exponent is found to depend on the particle type. The existence of the nanoparticle causes the short-time β-relaxation regime to shorten and the range of validity of the MCT shrink with respect to the bulk BLJ. It is also found that the behavior of intermediate scattering function (ISF) is in agreement with MCT prediction and in spite of the presence of gold nanoparticle the time temperature superposition principle at intermediate and low temperatures is still valid and the curves of ISF vs. t/ (T) fall onto a master curve.