Ab initio simulations of compressed liquid deuterium

Using ab initio molecular dynamics, we have investigated liquid deuterium u nder pressure, in a range of densities relevant to recent laser shock exper iments. Our results show that between four- and sixfold compression, and te mperatures between 5000 and 10 000 K, the Liquid goes continuously from a d issociation/recombination regime, where a substantial proportion of atoms f orm D-2 complexes, to a scattering regime, where mostly atoms are present. At about 10 000 K and sixfold compression, we find that the liquid is a poo r metal. Our simulations point at a compression alone the Hugoniot larger t han indicated by old data, but smaller than predicted by laser shock experi ments.