Equation of state and melting curve of helium to very high pressure

Abstract

An "exponential-six" interatomic pair potential, together with accurate statistical models for solid and liquid phases, is shown to yield good agreement with experimental pressure-volume and melting-curve data for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ up to 120 kbar. For pressures from 120 kbar to 250 Mbar, linear-muffin-tin-orbitals electron-band-theory calculations have been used to obtain the $T=0\mathrm{}$ pressure-volume isotherm. An effective pair potential is fitted to these results in order to compute the melting curve and shock Hugoniot curve in this region. The band-theory calculations indicate $T=0\mathrm{}$ metallization at 112 Mbar.