Enhancement of Atomic Diffusion due to Electron Delocalization in Fluid Metals

TL;DR

This paper introduces a theory explaining how electron delocalization near the Mott transition can unexpectedly enhance atomic diffusion in fluid metals, supported by quantum and classical simulations.

Contribution

It reveals a novel mechanism where electron delocalization increases atomic diffusion despite attractive interactions, combining quantum and classical modeling approaches.

Findings

Diffusion coefficient increases with electron delocalization.

Thermal fluctuations reduce repulsive core and attractive tail effects.

Classical simulations confirm the diffusion enhancement mechanism.

Abstract

We present a general theory of atomic self-diffusion in the vicinity of a Mott metal-insulator transition in fluid metals. Upon decreasing the electron correlation from the Mott insulating phase, the delocalization of electrons gives rise to an increasing attractive interatomic interaction, which is expected to introduce an additional friction, hence reducing the atomic diffusivity. Yet, our quantum molecular dynamics simulations find an intriguing enhancement of the diffusion coefficient induced by the emerging attractive force. We show that this counterintuitive phenomenon results from the reduction of the repulsive core and the suppression of the attractive tail by thermal fluctuations. The proposed scenario is corroborated by the Chapman-Enskog theory and classical molecular dynamics simulations on a standard liquid model based on the Morse potential. Our work not only provides a general mechanism of the attraction-facilitated diffusion enhancement in simple liquids, but also sheds new lights on the nontrivial effects of electron correlation on atomic dynamics.