Ionization/dissociation-driven first order phase transitions: on a new class of first order phase transitions

Abstract: In this work, we compare various models for describing the phase transition of the fluid hydrogen into a conducting state, including both chemical models of plasma and first-principle simulations within the framework of the density functional theory (DFT). The comparison of the results indicates the plasma nature of the phase transition in warm dense hydrogen. We propose a concept of a new class of first-order phase transitions: ionization or dissociation-driven phase transitions, with which the plasma phase transition in fluid hydrogen can be associated.