Theoretical calculation of thermodynamic properties and melting curves for hydrogen and deuterium

Thermodynamic properties of solid H2 and D2 are computed from quasiharmonic lattice dynamics corrected by anharmonic terms. Liquid properties are computed from a modified hard-sphere variational perturbation theory with a quantum correction. In these models we use an intermolecular pair potential which has been fitted to high pressure solid data. The computed solid and liquid free energies are used to find the melting curves of H2 and D2 up to room temperature. Agreement between experiment and theory is good.