Diffusion and jump-length distribution in liquid and amorphous Cu$_{33}$Zr$_{67}$

TL;DR

This study uses molecular dynamics to analyze atomic jump distributions in Cu$_{33}$Zr$_{67}$, revealing temperature-independent exponential jump length distributions and a transition from flow to jumps as the material cools.

Contribution

It provides new insights into atomic jump behaviors and diffusion mechanisms in liquid and amorphous Cu$_{33}$Zr$_{67}$, highlighting the transition from flow to jump dynamics.

Findings

Jump length distribution is temperature independent and exponential.

Shorter jumps dominate upon cooling.

Diffusion decreases below Arrhenius predictions due to reduced correlation factor.

Abstract

Using molecular dynamics simulation, we calculate the distribution of atomic jum ps in Cu$_{33}$Zr$_{67}$ in the liquid and glassy states. In both states the distribution of jump lengths can be described by a temperature independent exponential of the length and an effective activation energy plus a contribution of elastic displacements at short distances. Upon cooling the contribution of shorter jumps dominates. No indication of an enhanced probability to jump over a nearest neighbor distance was found. We find a smooth transition from flow in the liquid to jumps in the g lass. The correlation factor of the diffusion constant decreases with decreasing temperature, causing a drop of diffusion below the Arrhenius value, despite an apparent Arrhenius law for the jump probability.