Complicated diffusions of dense hydrogen in accurately predicted liquid-liquid phase transition

We present results of extensive calculations of the liquid-liquid phase transition (LLPT) in dense liquid hydrogen by path-integral molecular dynamics simulations. The satisfactory nonlocal density functional rVV10 and the hybrid functional PBE0 are used to improve the description of electronic structure of hydrogen. Within density functional theory calculations, we report the best consistent results to the quantum Monte Carlo and coupled electron-ion Monte Carlo results so far of the LLPT in dense liquid hydrogen. The critical point at temperature between 1500 K and 2000 K is estimated according to the equation of state. Interestingly, we find that the self-diffusion coefficients of dense liquid hydrogen exhibit complicated behaviors in the vicinity of the transition point, which can be used as a criterion to diagnose the phase transition, and the first-order LLPT and metallization of dense hydrogen do not occur simultaneously.