Phase and glass transitions in short-range central potential model systems: The case of C60

TL;DR

This study uses molecular dynamics simulations to explore phase transitions in a C60 model with a short-range potential, revealing conditions for vitrification, crystallization, and melting, with implications for complex fluids and biological systems.

Contribution

It demonstrates that phase transitions in a C60-like system occur at specific packing fractions, linking them to hard sphere transitions and extending understanding to similar complex fluid models.

Findings

Vitrification occurs at the same packing fraction as the glass transition in hard spheres.

Crystallization and melting are observed at packing fractions corresponding to their known transitions.

The results suggest broad applicability to other complex fluid systems with similar interactions.

Abstract

Extensive molecular dynamics simulations show that a short-range central potential, suited to model C60, undergoes a high temperature transition to a glassy phase characterized by the positional disorder of the constituent particles. Crystallization, melting and sublimation, which also take place during the simulation runs, are illustrated in detail. It turns out that vitrification and the mentioned phase transitions occur when the packing fraction of the system - defined in terms of an effective hard-core diameter - equals that of hard spheres at their own glass and melting transition, respectively. A close analogy also emerges between our findings and recent mode coupling theory calculations of structural arrest lines in a similar model of protein solutions. We argue that the conclusions of the present study might hold for a wide class of potentials currently employed to mimic interactions in complex fluids (some of which of biological interest), suggesting how to achieve at least qualitative predictions of vitrification and crystallization in those systems.