Nature of the metal-insulator transition in NbO2

We report a theoretical study of the structural phase transition and associated metal-to-insulator transition in NbO2 within density functional theory using the transition state theory as formulated in the generalized solid-state nudged elastic band method. Consistent with prior experimental work, we demonstrate that niobium dimerization is primarily driven by soft modes at the P point of the rutile Brillouin zone. In light of our results, it appears that the metal-to-insulator transition in NbO2 is driven by a second-order structural transition of the Peierls type.