Linear response calculations of electronic g-factors and spin-rotational coupling constants for diatomic molecules with a triplet ground state

Electronic g-factors for ESR spectra of a number of diatomic molecules with a ground X³Σ^- state and their electronic spin-rotational coupling constants have been calculated by a linear response method. General expressions are used for the second order correction to the electronic g-factor which account for spin-orbit coupling induced admixtures from all excited triplet states to the ground state orbital magnetism. First order corrections - the spin-Zeeman kinetic energy contribution and the one-electron spin-Zeeman gauge contribution - to the g-factor are also accounted for. Calculated g-factors and spin-rotational coupling constants are in a good agreement with available experimental data. In particular, the positive, anomalous, sign of the spin-rotational coupling constant of the PF radical is reproduced.