Stresses in semiconductors:Ab initiocalculations on Si, Ge, and GaAs

Explicit formulas for the calculation of stress are presented based on the stress theorem and the local-density-functional approximation. Norm-conserving pseudopotentials are applied in a plane-wave basis for calculations on the semiconductors Si, Ge, and GaAs. Besides the lattice constants and bulk moduli, complete sets of elastic constants are given, together with the optical phonon frequencies and internal-strain parameter. Electronic charge density structure factors, deformation potentials, and strain-induced splittings of phonons are given, as well as the nonlinear third-order elastic constants. Good agreement with experiment is found throughout, except for persistent deviations from the x-ray diffraction values for.