Density-Functional Theory of the nonlinear optical susceptibility: application to cubic semiconductors
Abstract
We present a general scheme for the computation of the time dependent (TD) quadratic susceptibility (
χ
(2)
) of an extended insulator obtained by applying the `
2n+1
' theorem to the action functional as defined in TD density functional theory. The resulting expression for
χ
(2)
includes self-consistent local-field effects, and is a simple function of the linear response of the system. We compute the static
χ
(2)
of nine III-V and five II-VI semiconductors using the local density approximation(LDA) obtaining good agreement with experiment. For GaP we also evaluate the TD
χ
(2)
for second harmonic generation using TD-LDA.