Slow Dynamics of the High Density Gaussian Core Model

TL;DR

This study investigates the slow dynamics and glass transition behavior of the high density Gaussian core model, revealing better agreement with mode-coupling theory and suppressed hopping effects compared to other glassformers.

Contribution

It demonstrates that the high density GCM aligns closely with mean-field predictions and exhibits unique dynamical features due to its long-range interactions.

Findings

Nucleation rate decreases with increasing density.

System exhibits supercooled fluid dynamics near glass transition.

Better MCT agreement than other models.

Abstract

We numerically study crystal nucleation and glassy slow dynamics of the one-component Gaussian core model (GCM) at high densities. The nucleation rate at a fixed supersaturation is found to decrease as the density increases. At very high densities, the nucleation is not observed at all in the time window accessed by long molecular dynamics (MD) simulation. Concomitantly, the system exhibits typical slow dynamics of the supercooled fluids near the glass transition point. We compare the simulation results of the supercooled GCM with the predictions of mode-coupling theory (MCT) and find that the agreement between them is better than any other model glassformers studied numerically in the past. Furthermore, we find that a violation of the Stokes-Einstein relation is weaker and the non-Gaussian parameter is smaller than canonical glassformers. Analysis of the probability distribution of the particle displacement clearly reveals that the hopping effect is strongly suppressed in the high density GCM. We conclude from these observations that the GCM is more amenable to the mean-field picture of the glass transition than other models. This is attributed to the long-ranged nature of the interaction potential of the GCM in the high density regime. Finally, the intermediate scattering function at small wavevectors is found to decay much faster than its self part, indicating that dynamics of the large-scale density fluctuations decouples with the shorter-ranged caging motion.