Solid hydrogen and deuterium. I. Ground-state energy calculated by a lowest order constrained-variation method

Abstract

The ground-state energy of solid hydrogen and deuterium is calculated by means of a modified variational lowest order constrained-variation (LOCV) method. Both fcc and hcp H₂ and D₂ are considered, and the calculations are done for five different two-body potentials. For solid H₂ we obtain theoretical results for the ground-state binding energy per particle from −74.9 K at an equilibrium particle density of 0.700 σ⁻³ or a molar volume of 22.3 cm³/mole to −91.3 K at a particle density of 0.725 σ⁻³ or a molar volume of 21.5 cm³/mole, where σ=2.958 Å. The corresponding experimental result is −92.3 K at a particle density of 0.688 σ⁻³ or a molar volume of 22.7 cm³/mole. For solid D₂ we obtain theoretical results for the ground-state binding energy per particle from −125.7 K at an equilibrium particle density of 0.830 σ⁻³ or a molar volume of 18.8 cm³/mole to −140.1 K at a particle density of 0.843 σ⁻³ or a molar volume of 18.5 cm³/mole. The corresponding experimental result is −137.9 K at a particle density of 0.797 σ⁻³ or a molar volume of 19.6 cm³/mole.