Molecular dynamics study on the effect of interaction potentials on the pressures of high density helium

Abstract

The thermodynamic properties of pure high density helium and helium bubbles in metals are investigated using molecular dynamics method. The Lennard-Jones potential and the exponential-six potential are used to describe the interaction between helium atoms respectively. The results show that the short-range repulsive part of He–He potential has a great effect upon the pressure of pure high density helium. Because the exponential-six potential is softer than the Lennard-Jones potential in short-range part, the pressures of pure high density helium obtained by the exponential-six potential are lower and have a better agreement with available experimental data. For helium bubbles in metals, the He-Metal interactions can influence the uniformity of helium atoms within helium bubbles so that the pressures inside helium bubbles are higher than that of pure helium with the same average density. However, the differences between them decrease with increasing temperature.