Ion core effect on transport characteristics in warm dense matter

TL;DR

This study investigates how ionic core effects influence transport properties like diffusion and viscosity in warm dense matter, using molecular dynamics simulations of shocked silicon to reveal significant impacts on these properties.

Contribution

It introduces an effective potential approach combined with MD to analyze ionic core effects on transport properties in warm dense matter, highlighting their significant influence.

Findings

Ion core effects decrease ion diffusion coefficients.

Ion core effects can increase or decrease viscosity depending on coupling strength.

MD simulations show notable differences when ion core effects are included.

Abstract

An effective potential approach in combination with the molecular dynamics (MD) method was used to study the effect of the ionic core on the transport properties of ions in the warm dense matter regime. As an example, we considered shocked silicon. The results of MD simulations within microcanonical ensemble were analyzed by computing the mean squared displacement (MSD) and the velocity autocorrelation function (VAF) of particles. The MSD and VAF are used to compute the diffusion coefficient of ions. The results are compared with the data computed neglecting the ion core effect. It is found that the ion core effect leads to a significant decrease of the diffusion coefficient. Additionally, we computed the viscosity coefficient of ions using the Green-Kubo relation connecting viscosity and the stress autocorrelation function. It is revealed that the ion core effect can cause increase or reduction of the viscosity coefficient depending on the strength of inter-ionic coupling.