Ab initio calculations of electronic g-factors by means of multiconfiguration response theory

A response theory algorithm is derived for calculations of the second-order contribution to the electronic g-tensor, that is the combined perturbation of the orbital Zeeman effect and spin–orbit coupling, for single- and multiconfiguration reference states. Sample calculations are carried out for the NH and O2 molecules, comparing with experimental data and testing different parametrizations of the wavefunctions.