Cluster Glass Transition of Ultrasoft-Potential Fluids at High Density

TL;DR

This study uses molecular dynamics simulations to explore the complex glass transition behaviors of ultrasoft-potential fluids at high densities, revealing multiple cluster-glass phases and higher order singularities.

Contribution

It uncovers the existence of multiple cluster-glass phases with distinct particle counts and identifies higher order singularities near phase boundaries, advancing understanding of ultrasoft fluid dynamics.

Findings

Multiple cluster-glass phases with different cluster sizes

Observation of higher order singularity with logarithmic relaxation

Decoupling of self- and collective dynamics in cluster glasses

Abstract

Using molecular dynamics simulation, we investigate the slow dynamics of a supercooled binary mixture of soft particles interacting with a generalized Hertzian potential. At low density, it displays typical slow dynamics near its glass transition temperature. At higher densities, particles bond together, forming clusters, and the clusters undergo the glass transition. The number of particles in a cluster increases one by one as the density increases. We demonstrate that there exist the multiple cluster-glass phases characterized by a different number of particles per cluster, each of which is separated by distinct minima. Surprisingly, a so-called higher order singularity of the mode-coupling theory signaled by a logarithmic relaxation is observed in the vicinity of the boundaries between monomer and cluster glass phases. The system also exhibits rich and anomalous dynamics in the cluster glass phases, such as the decoupling of the self- and collective dynamics.