Observation of Single Transits in Supercooled Monatomic Liquids

TL;DR

This paper reports the first direct observation of transits in supercooled monatomic liquids, showing correlated particle shifts occurring rapidly and involving small groups of particles, based on molecular dynamics simulations.

Contribution

It provides the first direct evidence of transit motion in monatomic liquids at thermal equilibrium through molecular dynamics simulations.

Findings

Transits involve 2 to 11 particles with mean shifts of 0.4 R_1 in argon and 0.25 R_1 in sodium.

Transits occur approximately within one vibrational period, indicating they are fast events.

First direct observation of transit motion in monatomic liquids in thermal equilibrium.

Abstract

A transit is the motion of a system from one many-particle potential energy valley to another. We report the observation of transits in molecular dynamics (MD) calculations of supercooled liquid argon and sodium. Each transit is a correlated simultaneous shift in the equilibrium positions of a small local group of particles, as revealed in the fluctuating graphs of the particle coordinates versus time. This is the first reported direct observation of transit motion in a monatomic liquid in thermal equilibrium. We found transits involving 2 to 11 particles, having mean shift in equilibrium position on the order of 0.4 R_1 in argon and 0.25 R_1 in sodium, where R_1 is the nearest neighbor distance. The time it takes for a transit to occur is approximately one mean vibrational period, confirming that transits are fast.