AB-INITIO MOLECULAR-DYNAMICS STUDY OF THE STRUCTURAL AND TRANSPORT-PROPERTIES OF LIQUID GERMANIUM

We describe the results of ab initio molecular-dynamics simulations of liquid Ge at five temperatures ranging from 1250 to 2000 K. The elect ronic structure is calculated using the local-density approximation an d generalized norm-conserving pseudopotentials. The calculations yield the pair correlation function, the static structure factor, the bond- angle distribution function, the electronic density of stales, the ato mic self-diffusion coefficient, and finally the ac conductivity. Near melting, the structure factor has the experimentally observed shoulder on the high-k side of the principal peak, which becomes progressively less distinct at higher temperatures. The bond-angle distribution fun ction indicates the persistence of covalent bonding for shorter bond l engths in the Liquid state. The electronic density of states is metall ic at all the temperatures with a pseudogap at a binding energy of 4.6 eV. The diffusion constant shows a sharp rise between 1250 and 1500 K (1.2 x 10(-4) - 2.0 x 10(-4) cm(2) s(-1)) and increases less rapidly at higher temperatures, to only 2.3 x 10(-4) cm(2) s(-1) at 2000 K.