Quantum path integral molecular dynamics simulations on transport properties of dense liquid helium

TL;DR

This study uses advanced quantum simulations to analyze how nuclear quantum effects influence the transport properties of dense liquid helium under astrophysical conditions, revealing significant deviations from classical predictions.

Contribution

It introduces improved centroid path-integral simulations combined with density functional theory to accurately capture nuclear quantum effects in dense helium.

Findings

Quantum effects increase self-diffusion in dense helium.

Quantum effects decrease shear viscosity compared to classical models.

Nuclear quantum effects are crucial at certain astrophysical conditions.

Abstract

Transport properties of dense liquid helium under the conditions of planet's core and cool atmosphere of white dwarfs have been investigated by using the improved centroid path-integral simulations combined with density functional theory. The self-diffusion is largely higher and the shear viscosity is notably lower predicted with the quantum mechanical description of the nuclear motion compared with the description by Newton equation. The results show that nuclear quantum effects (NQEs), which depends on the temperature and density of the matter via the thermal de Broglie wavelength and the ionization of electrons, are essential for the transport properties of dense liquid helium at certain astrophysical conditions. The Stokes-Einstein relation between diffusion and viscosity in strongly coupled regime is also examined to display the influences of NQEs.