Zero-point motion and the insulator-metal transition in solid molecular hydrogen.

Abstract

Candidate structures for molecular hydrogen in the 150 GPa pressure range are examined using ab initio frozen-phonon calculations in the local density approximation. Vibronic zero-point motion yields important contributions to the relative energies of metallic versus insulating phases. A first-order insulator-metal transition is found, with features in qualitative accord with experiment. Our results imply that an observed transition in solid molecular hydrogen is an insulator-metal--molecular-orientation transition driven by the vibron zero-point motion itself.