Calculation of the nonlinear susceptibility for optical second-harmonic generation in III-V semiconductors

We calculate both linear and nonlinear optical response in the static limit for AlP, AlAs, GaP, and GaAs in the local-density approximation with and without a scissors operator, including local-field effects. The calculation agrees with the measurement of Levine and Bethea to within 15%. The derivatives d ln^ (2) /d lna, for lattice constant a, are predicted to be from 1. 7 to 6. 6 times the values obtainable from existing models. The calculated static dielectric constants _ are within 2% of measured values; calculated results for d ln_/d lna are also presented. The scissors operator alters _ up to 25% but alters ^ (2) by a factor of 2.