Electron paramagnetic resonance g-tensors from state interaction spin-orbit coupling density matrix renormalization group

We present a state interaction spin-orbit coupling method to calculate electron paramagnetic resonance g-tensors from density matrix renormalization group wavefunctions. We apply the technique to compute g-tensors for the TiF₃ and CuCl₄^{2 -} complexes, a [2Fe-2S] model of the active center of ferredoxins, and a Mn₄CaO₅ model of the S2 state of the oxygen evolving complex. These calculations raise the prospects of determining g-tensors in multireference calculations with a large number of open shells.