The compression property of hydrogen at megabar pressures and the form of the repulsive interaction potential in hydrogen at short distances

TL;DR

This paper investigates how the repulsive interaction potential between hydrogen atoms changes at very high pressures, explaining experimental compression data through a modified potential model.

Contribution

It introduces a model showing the decreasing slope of the repulsive potential at short distances, aligning with recent high-pressure hydrogen experiments.

Findings

The repulsive potential slope decreases with decreasing internuclear distance.

This form explains the observed reduction in compression curve slopes.

The model aligns with experimental data at megabar pressures.

Abstract

It is shown that the slope of the repulsive part of the interaction potential between hydrogen atoms above the dissociation limit decreases with decreasing internuclear separation. Such a form of the repulsive potential explains the reduction of the shock and quasi-isentropic compression curve slopes of hydrogen isotopes at megabar pressures obtained in recent experiments [R. F. Trunin, V. D. Urlin, and A. B. Medvedev, Phys.-Usp. \textbf{53}, 577 (2010), R. I. Ilkaev, \textit{et al.}, AIP Conf. Proc. \textbf{706}, 73 (2004)].