Investigation of the relation between local diffusivity and local inherent structures in the Kob-Andersen Lennard-Jones model

TL;DR

This study investigates how local basin depths in the potential energy landscape influence particle diffusion in a Lennard-Jones system, linking thermodynamics and dynamics to explain supercooled state behaviors.

Contribution

It introduces a model-free method to connect local basin properties with particle diffusion, revealing the non-linear relationship affecting supercooled dynamics.

Findings

Diffusion coefficient can be expressed as a sum over basin contributions.

Non-linearity in local diffusion vs. basin depth explains supercooled dynamics.

Evidence supports the role of potential energy landscape in dynamic heterogeneities.

Abstract

We analyze one thousand independent equilibrium trajectories of a system of 155 Lennard Jones particles to separate in a model-free approach the role of temperature and the role of the explored potential energy landscape basin depth in the particle dynamics. We show that the diffusion coefficient $D$ can be estimated as a sum over over contributions of the sampled basins, establishing a connection between thermodynamics and dynamics in the potential energy landscape framework. We provide evidence that the observed non-linearity in the relation between local diffusion and basin depth is responsible for the peculiar dynamic behavior observed in supercooled states and provide an interpretation for the presence of dynamic heterogeneities.