Structure and band gaps of Ga-(V) semiconductors: The challenge of Ga pseudopotentials

Design of gallium pseudopotentials has been investigated for use in density functional calculations of zinc-blende-type cubic phases of GaAs, GaP, and GaN. A converged construction with respect to all-electron results is described. Computed lattice constants, bulk moduli, and band gaps vary significantly depending on pseudopotential construction or exchange-correlation functional. The Kohn-Sham band gap of the Ga-(V) semiconductors exhibits a distinctive and strong sensitivity to lattice constant, with near-linear dependence of gap on lattice constant for larger lattice constants and a Γ-X crossover that changes the slope of the dependence. This crossover occurs at ≈98, 101, and 95% deviation from the equilibrium lattice constant for GaAs, GaP, and GaN, respectively.