Hopping conductivity in dense hydrogen fluid

A transition from semiconducting behavior to conductivities typical for simple metals was observed in dense hydrogen fluid at 1.4 Mbar and 3000 K in multiple shock-compression experiments [S. T. Weir, A. C. Mitchell, and W. J. Nellis, Phys. Rev. Lett. 76, 1860 (1996)]. Various mechanisms such as band gap closure, self-doping, or thermally activated transport have been proposed to explain this nonmetal-to-metal transition. We perform an exploratory calculation of the hopping conductivity in dense hydrogen fluid which is considered as a partially dissociated system of H atoms and H₂ molecules. It is shown that hopping processes between H atoms play an important role in this nonmetal-to-metal transition.