High Temperature Raman analysis of Hydrogen Phase IV from Molecular Dynamics

We extend our previous studies on phase IV of solid hydrogen by employing larger cells and k-sampling. We show that uncorrelated hexagonal rotations in the weakly bounded G"-layers are needed to account for the experimentally measured Raman spectrum. In large simulations we find no evidence of proton diffusion or layer fluctuations, which we believe are the result of finite size effects. In calculations at higher pressures (above 400 GPa) we identify a new possible candidate for phase IV. We, finally, proposed a revised phase diagram based on our previous and present results.