Spin-orbit coupling constants from coupled-cluster response theory

Abstract

A scheme for the calculation of spin-orbit coupling constants using coupled-cluster (CC) electronic structure methods is described based on response-theory expressions for transition properties. An implementation is reported for singlet–triplet transitions within the coupled-cluster singles and doubles (CCSD) approximation. An atomic mean-field representation of the spin-orbit interaction is used to simplify the calculation of spin-orbit coupling constants. Sample calculations are presented for spin-orbit couplings for the 1¹Σ⁺→1³Π transitions for BH and AlH and for the 1¹A′→1³A″ and the 1³A″→1¹A″ transitions for the silylenes HSiX, X=F, Cl, Br, and are compared to results obtained from full configuration interaction (FCI) calculations with the full Breit-Pauli spin-orbit operator.