  The technologically important problem of predicting Auger recombination
lifetimes in semiconductors is addressed by means of a fully first--principles
formalism. The calculations employ highly precise energy bands and wave
functions provided by the full--potential linearized augmented plane wave
(FLAPW) code based on the screened exchange local density approximation. The
minority carrier Auger lifetime is determined by two closely related
approaches: \emph{i}) a direct evaluation of the Auger rates within Fermi's
Golden Rule, and \emph{ii}) an indirect evaluation, based on a detailed balance
formulation combining Auger recombination and its inverse process, impact
ionization, in a unified framework. Calculated carrier lifetimes determined
with the direct and indirect methods show excellent consistency \emph{i})
between them for $n$-doped GaAs and \emph{ii}%) with measured values for GaAs
and InGaAs. This demonstrates the validity and accuracy of the computational
formalism for the Auger lifetime and indicates a new sensitive tool for
possible use in materials performance optimization.
