Composition dependence of the structure and the electronic states of liquid K-Pb alloys: ab initio molecular-dynamics simulations

We have carried out ab initio molecular-dynamics simulations for the compou nd-forming liquid K-Pb alloys to investigate the composition dependence of their ionic structure and electronic states. It is shown that the tetrahedr al Pb-4(4-) clusters, which are the so-called 'Zintl ions' seen in the crys talline compound KPb, appear for the liquid K-rich alloy, while the Zintl i ons are connected to each other and a complex structure is formed for the l iquid equiatomic alloy. The observed structure factor characterized by the first sharp diffraction peak can be reproduced and it is found that the pre peak arises from the intermediate-range ordering of the Zintl ions. The com position dependence of the resistivity is well reproduced by means of the K ubo-Greenwood formula and its characteristic features are understood on the basis of the calculated electronic states and the ionic structure obtained .