Pairing instabilities in dense hydrogen

Abstract

Recent Raman-effect and equation-of-state measurements in highly compressed molecular hydrogen can be combined to show that it should become dynamically unstable towards dissociation at pressures in the vicinity of 3 Mbar. In spite of relatively small shifts in the vibron modes, it can be shown that the intramolecular potential suffers very significant weakening at high compression, this trend being fully understandable by application of the rigorous cusp condition, which constrains the electron density at the protons. At high densities quantum-solid effects are appreciable and when revealed in the band structure through zero-phonon terms can lead to modifications of band-gap closure conditions.