The equation of state of hydrogen from an ab initio potential surface

Abstract

An accurate ab initio calculation of the H₂−H₂ potential surface has been used to calculate the thermodynamic properties of hydrogen over the temperature range 0–3000 K and at pressures up to 1 Mbar. A comparison with experimental data, including pVT measurements, second virial coefficients and ground state energy, suggests that the surface is significantly in error in the region of the potential minimum. The surface has been scaled semi-empirically to give predictions in acceptable agreement with experimental data. A detailed study of the high density calculations indicated that effects due to the non-sphericity of the potential surface are small.