Electronic structure of random Al0.5Ga0.5As alloys: Test of the "special-quasirandom-structures" description.

TLDR: Over a broad range of scattering strengths, the dominant spectral features predicted by the first two techniques are well reproduced by calculations for an SQS with 16 atoms/unit-cell ( SQS-8'', suggesting that the SQS approach might also be useful in cases where the other methods are difficult to apply.

Abstract: The spectral properties of an ${\mathit{sp}}^{3}$${\mathit{s}}^{\mathrm{*}}$ tight-binding Hamiltonian for a random, unrelaxed ${\mathrm{Al}}_{0.5}$${\mathrm{Ga}}_{0.5}$As alloy are calculated using three different techniques: the coherent-potential approximation, the recursion method (as applied to a g2000 atom supercell), and the recently introduced ``special-quasirandom-structures'' (SQS) approach. Over a broad range of scattering strengths, the dominant spectral features predicted by the first two techniques are well reproduced by calculations for an SQS with 16 atoms/unit-cell (``SQS-8''). This suggests that the SQS approach might also be useful in cases where the other methods are difficult to apply, e.g., in first-principles calculations for structurally relaxed alloys.