Characterization of the State of Hydrogen at High Temperature and Density

Fermionic path integral Monte Carlo simulations have been applied to study the equilibrium properties of the hydrogen and deuterium in the density and temperature range of 1.6 < rs < 14.0 and 5000K < T < 167000K. We use this technique to determine the phase diagram by identifying the the plasma, the molecular, atomic and metallic regime. We explain how one can identify the phases in the path integral formalism and discuss the state of hydrogen for 5 points in the temperature-density plane. Further we will provide arguments for the nature of the transitions between the regimes.