Structure and electronic states of liquid Na-Pb alloys by an ab initio molecular-dynamics simulation

We have carried out an ab initio molecular-dynamics simulation for the liqu id Na0.8Pb0.2 and Na0.5Pb0.5 alloys to investigate the ionic structure, the electronic states and especially the existence of the so-called 'Zintl ion ' or 'octet compound'. The existence of these chemical units is not confirm ed, but rather the intermediate-range ordering of Pb ions is seen for the l iquid Na0.8Pb0.2 alloy. It is found that this ordering of Pb ions leads to the first sharp diffraction peak of the observed structure factor. The comp osition dependence of the electronic states is explained on the basis of th e ionic configuration. (C) 1999 Elsevier Science B.V. All rights reserved.