RMC MODELING OF THE STRUCTURE OF EXPANDED LIQUID MERCURY ALONG THE COEXISTENCE CURVE

The structure factors of liquid Hg at 13 temperatures/pressures along the liquid-vapour co-existence curve have been modelled using the reve rse Monte Carlo (RMC) method. The resulting configurations are consist ent with the idea that the liquid contains atoms which can be consider ed as being in a 'metallic' environment, characterized by a larger num ber of near neighbours at a relatively short distance, and atoms which are in a 'semiconducting' environment, characterized by a smaller num ber of neighbours at a slightly longer distance. As the temperature in creases and the density decreases, the proportion of 'metallic' atoms decreases. The metal-non-metal transition at rho(M-NM) approximate to 9 g cm(-3) (0.027 Angstrom(-3)) may be considered as a percolation tra nsition in the metallic bond network. At lower densities the metal ato ms occur in isolated clusters, and there is some evidence that the cri tical point at rho(c) = 5.8 g cm(-3) (0.0174 Angstrom(-3)) coincides w ith the disappearance of these clusters.