Structural relaxation of amorphousZr70Cu30and its effect on the electronic properties

A model structure for amorphous ${\mathrm{Zr}}_{70}$ ${\mathrm{Cu}}_{30}$ is obtained starting from a random distribution of hard spheres which is then relaxed by molecular dynamics, with the assumption that the interatomic forces may be represented by central potentials. The atomic configurations with different degrees of relaxation are used as a basis for the calculation of the electronic d-band densities of states. In this calculation the recursion method together with a tight-binding Hamiltonian is used. It is found that the relaxation procedure increases the average coordination number and the average first-neighbor distances. Similar behavior is observed experimentally by thermal annealing in real amorphous systems. We thus believe that the changes in the properties calculated for our model structures may adequately represent those of real systems on annealing. The effect of relaxation on local and total densities of states is reported: The peak at the Cu atomic level and the minimum at the center of the band are enhanced by relaxation. The s electrons are included in a second stage and the hybridization effects are studied. Finally the behavior of the density of states at the Fermi level with relaxation is discussed.