Appendix IV

The Phase Diagram of Hydrogen

 

Hydrogen phase diagram as function of temperature vs. mass density. The solid lines show phase boundaries belonging to discontinuous transitions while dash-dotted lines represent continuous transitions that were estimated from PIMC simulations. Controversial is the nature of the transition from the molecular to the metallic fluid. The PIMC simulations by Magro et al. (1996) have suggested a first order plasma phase transition. At zero temperature, a first order transition from the molecular to the metallic solid has been predicted by Ceperley and Alder (1987). The gas-liquid coexistence region (shaded area) with the critical point and gas-liquid-solid triple point was taken from Kitamura and Ichimaru (1998).