Influence of nuclear quantum effects on metastable states of warm dense hydrogen

Previously, it has been effectively shown that nuclear quantum effects (NQE) considerably influence the prediction of the warm dense hydrogen phase diagram. Here, we study the influence of NQE on the parameters of the conducting state formation in warm dense hydrogen using path integral molecular dynamics (PIMD) within the framework of the finite temperature density functional theory approach (FTDFT). Both molecular and conducting metastable branches are obtained along the 700 and 1000 K isotherms in the PBE functional, as well as 500 K in the BLYP functional, which are expected for the first order phase transition [Landau and Lifshitz. Statistical Physics. Vol. 5. Elsevier, 2013]. Proton-proton pair correlation functions (PCF) and conductivity are calculated to diagnose metastable states. The results are compared with isotherms obtained for "classical" protons within the framework of quantum molecular dynamics (QMD). The latent heat of the transition to the conducting state is estimated based on the calculation of pairwise entropy. Strong overlapping of metastable and stable branches of the isotherm points is found in warm dense hydrogen.