Nonmetal-to-metal transition in dense fluid nitrogen at high pressure

We calculate the electrical conductivity and the equation of state of dense fluid nitrogen for high pressures up to several megabars by using ab initio molecular dynamics simulations. We determine the instability region of a first-order liquid-liquid phase transition which results from an abrupt dissociation of nitrogen molecules. This transition is accompanied by a nonmetal-to-metal transition (metallization) of the fluid and corresponding structural changes from a molecular to a polymeric phase. We compare our new data with earlier theoretical results and available experiments.