Computation of one and two electron spin‐orbit integrals

Methods for the computation of one‐ and two‐electron spin‐orbit integrals over Gaussian‐type basis functions are presented. We show that existing nuclear‐attraction and electron‐repulsion integral codes can be readily adapted for the efficient evaluation of spin‐orbit integrals; in particular, one can take advantage of recent advances in the computation of derivative integrals. Recurrence relations for the nuclear attraction integrals are also developed.