Impact of length scale of attraction on the dynamical heterogeneity: a molecular dynamics simulation study

Abstract

We investigate the role of the length scale of attraction on the dynamical heterogeneity in three-dimensional core-softened (CS) model liquid having interaction potential of two different length scales. Using the simple CS model, we have shown that the presence of heterogeneity is attributed to the existence of attractive interactions in a system. The time scale associated with the peak position of the non-Gaussian parameter is found to be strongly dependent on the temperature for different length scale of attraction. The dynamical heterogeneity dramatically decreases with the increase in temperature. We further characterize dynamical heterogeneity by calculating new non-Gaussian parameter which indicates the existence of much longer relaxation timescale than that suggested by the peak position in the non-Gaussian parameter. Furthermore, we have shown the presence of particles, whose displacement distribution deviates from the Gaussian distribution and contributes towards the origin/presence of heterogeneity. Dynamical heterogeneity strongly depends on the length scale as well as the strength of attraction. System A which does not show that dynamical heterogeneity corresponds to repulsive interaction with large interaction length scale. System B which corresponds to attractive interaction with a small length scale of interaction shows dynamical heterogeneity. Non-Gaussian parameter $$[\alpha _2 ( t )]$$ for system A and system B at different temperatures