Calculation of the electronic properties of Ni-P amorphous alloys

We have simulated the atomic structure of Ni-P amorphous alloys for several concentrations (${\mathrm{Ni}}_{75}$ ${\mathrm{P}}_{25}$, ${\mathrm{Ni}}_{80}$ ${\mathrm{P}}_{20}$, and ${\mathrm{Ni}}_{85}$ ${\mathrm{P}}_{15}$), and have calculated their electronic properties. The atoms are spread randomly in a periodically repeated cell and then relaxed using Weber-Stillinger pair potentials to a local minimum potential energy. We have constructed eight such cells for each concentration. Because the unit cell (80 or 160 atoms) is larger than the electronic mean free path, we can assume the electronic properties are independent of boundary conditions. We impose periodic boundary conditions, which is equivalent to calculating the band structure at k=0 of the periodically extended unit cell. Using linearized Korringa-Kohn-Rostoker (KKR) band theory, we have calculated the total density of states, component- and angular-momentum-decomposed densities of states, degree of localization, and current matrix elements for the electrons. We find very little localization of the electrons near the Fermi energy. We also have calculated the electrical resistivity and reflectivity as a function of frequency and concentration using the Kubo formula. Finally we have compared our calculated results with experiment and with results obtained from the effective-medium approximation and from the KKR coherent-potential approximation.