Selection rules for indirect transitions and effect of time reversal symmetry

Abstract

Selection rules for indirect transitions are derived starting from a geometrical interpretation of the Brillouin zone. The effect of time reversal symmetry is included in the procedure. The final results, valid both for single group and double group representations, are presented in a way very convenient for operational applications. The case of diamond lattice is given as a specific example. The comparison between this treatment and previous ones is discussed.