The microscopic mechanism of the metal-semiconductor transition in liquid alkali-Te mixtures - Ab initio molecular-dynamics simulations

To investigate the microscopic mechanism of the metal-semiconductor transit ion, the interplay between the structural and electronic properties of liqu id RbxTe1-x, and KxTe1-x, mixtures (x = 0.0, 0.2 and 0.5) are studied by ab initio molecular-dynamics simulations. It is shown that the transition fro m metallic to semiconducting states by adding Rb atoms is related to the st ructural change in the Te chain and that almost complete charge transfer ho m Rb(K) to Te occurs in the mixtures. For x = 0.2, the Te chains are relati vely stabilized, since the interchain interactions are suppressed by Rb+(K) ions, and the system becomes semiconducting. For x = 0.5, more than half of Te atoms form Te-2(2-) dimers, which are the so-called Zintl ions. The c orrelation between the spatial distribution of the transferred charge in th e Te chains and the positions of Rb+(K+) ions is investigated.