AB-INITIO MOLECULAR-DYNAMICS FOR EXPANDED AND COMPRESSED LIQUID ALKALI-METALS

The structural and the electronic properties of liquid alkali metals a long the liquid-vapour coexistence curve and along the melting curve a re investigated by the ab initio molecular dynamics (MD) simulation, i n which the Kohn-Sham energy functional is minimized for each ionic co nfiguration of the MD step using the preconditioned conjugate-gradient method. It is shown for the expanded liquid Rb that the calculated st ructural functions are in good agreement with the experiments and that the electronic states are strongly correlated with the ionic configur ation and tend to localize due to the large spatial fluctuation of ion ic density with decreasing density. As for the compressed liquid Rb un der high pressure, the structure obtained by the simulation agrees wel l with the recent experiment; that is, for the pressure less than 3 GP a the liquid contracts uniformly but above 3 GPa it starts to deviate from the simple uniform compression. This structural feature is relate d to the electronic s-d transition due to the high pressure, which is clearly seen in the calculated density of states.