An empirical pseudopotential method is demonstrated for realistically and accurately calculating the band structure of partially CuPt ordered ${\mathrm{Ga}}_x{\mathrm{In}}_{1-x}\mathrm{P}$ alloys. A sufficiently large supercell of ∼3500 atoms, with all atomic positions relaxed by applying a valence force field method, is used to simulate the (Ga,In) distribution in the partially ordered alloy with the order parameter η varying from 0 to 1. While agreeing very well with experimental data in the experimentally verifiable region $\eta <0.5,$ our results illustrate that a commonly accepted interpolation scheme (i.e., the ${\eta }^2$ rule) is grossly inaccurate for determining certain primary band structure parameters (e.g., the band gap) between $\eta =0\mathrm{}$ and $\eta =1.\mathrm{}$

• Received 5 March 2001

DOI:https://doi.org/10.1103/PhysRevB.63.201312