Self-Consistent Orthogonalized-Plane-Wave Band Calculation on GaAs

The self-consistent orthogonalized-plane-wave (SCOPW) method is used to calculate the electronic structure of GaAs. It was found that the results obtained using Slater's approximation for the exchange operator match experiment more closely than those obtained using the other approximations. The comparison of the SCOPW results with photoemission, hydrostatic pressure, and reflection data is presented. Three minima in the conduction band are found; the lowest minimum occurs at the $\Gamma$ point; the second lowest minimum, which occurs at the $L$ point, was 0.38 eV above the $\Gamma$-point minimum; and the highest minimum, occurring along $\Delta$ at ($\frac{\pi }{a}$) (0.82, 0, 0), was 0.82 eV above the $\Gamma$-point minimum. This last minimum is about ½ eV higher than is predicted by the customary experimental interpretation. Using the same SCOPW programs, GaP energy bands were calculated and the estimates of the band gaps of $\mathrm{Ga}{\mathrm{As}}_{1-X}{\mathrm{P}}_x$ are also given.