Spin-polarized hydrogen, deuterium, and tritium, II: pressure and compressibility calculated by a lowest order constrained-variation method

The pressure and the compressibility of spin-polarized H ↓, D ↓, and T ↓ are obtained from ground-state energies calculated by means of a modified variational lowest order constrained-variation method. The pressure and the compressibility are calculated or estimated from the dependence of the ground-state energy on density or molar volume, generally in the density region from 0 to 1.5σ-3 corresponding to a molar volume of more than 20 co3/mol, where σ = 3.69 A (1A= 10-10 m); the calculations are done for five different two-body potentials. Theoretical results for the pressure are 54.1-57.9 atm for spin-polarized H ↓, 18.4-23.4 atm for spin-polarized D ↓, and 5.6-12.9 atm for spin-polarized T ↓ at a particle density of 0.50σ-3 or a molar volume of 60 cm3/mol (1 atm = 101 kPa). Theoretical results for the compressibility are 51 x 10-4 - 54 x 10-4 atm -1 for spin-polarized H ↓, 108 x 10-4 - 120 x 10-4 atm-1 for spin-polarized D ↓, and 162 x 10-4 - 224 x 10-4 atm -1 for spin-polarized T ↓ at a particle density of 0.50σ-3 for a molar volume of 60 cm3/mol. The relative agreement between results for different potentials is somewhat better for higher densities. (author). 7 refs., 6 tabs., 12 figs