Solid Hydrogen: Ground-State Energy, Pressure, and Compressibility

The ground-state energy, the pressure, and the compressibility of solid molecular hydrogen is calculated by means of a modified Brueckner theory. The BetheGoldstone equation is solved to give the reaction matrix or an effective interaction in coordinate space; the ground-state energies for normal hydrogen and deuterium are calculated. Also, the pressure and the compressibility is estimated from the dependence of the ground-state energy on density or molar volume. Both hcp and fcc structures are considered. Theoretical results for the groundstate energy per particle are -82 K for solid hydrogen at a molar volume of 22 cm(3)/mole and -135 K for solid deuterium at a molar volume of 19 cm3/mole. The corresponding experimental results are 92 and 138 K, respectively. We obtain zero pressure for solid hydrogen at a molar volume of 22.45 cm31mole and for solid deuterium at a molar volume of 19.2 cm3/mole. The corresponding experimental results are 22.65 and 19.56 cm(3)/mole, respectively. Theoretical results for the compressibility at zero pressure are 5.3 x 10 atm(-1) for solid hydrogen and 2.6 x 10(3)/ m(-1) for solid deuterium. The corresponding experimental results are 4.9 x 10(-4) and 3.0 x 10(-4) atm(-1), respectively. The agreement with experimental results is reasonably good since higher order cluster terms are not included in this first approximation.