4 OPW calculations of electronic transport coefficients of aluminium containing point defects

Abstract

The scattering of conduction electrons on dilute point defects in aluminium was investigated, for zero temperature, by pseudopotential calculations considering the realistic form of the Al Fermi surface (FS) and band structure. The 4-OPW wavefunctions, band velocities and FS curvatures were calculated for 1,300 pointsk on 1/48 (cubic symmetry element) of the FS. The scattering potentials were obtained as follows: for the impurities Ge, Mg, Zn, and Ga tabulated pseudopotentials were used and rescreened for the electron density of Al, the vacancy was treated as a missing Al atom and the [100] dumbbell interstitial as two Al atoms with a vacancy in between (always with strain field corrections). The scattering matrixP kk′ was obtained in first order Born approximation. The linearized Boltzmann equation was solved numerically by iteration, for zero magnetic field and for a reduced set of 109 points on 1/48 FS, to yield the anisotropic transport relaxation timesτ k and lifetimesτ 0 . Theτ k were interpolated for the 1,300 points again and inserted into low-field FS integrals for the galvanomagnetic coefficients which depend sensitively on the details of the FS and the anisotropy ofτ k . Without any free parameter, our results agree very well with experimental data for the case of Ge, Mg, and Zn impurities, and less so for the homovalent Ga impurities and for the self-defects. The diffusion thermopower was also calculated.