The theoretical study of metal-insulator transition of VO2

Abstract

The first principle methods have been used to investigate the electronic structure and thermal property of VO2 in rutile or monoclinic phase. The strong electronic correlation of V(3d) was described by the local density plus Hubbard U approximation, and the phonon density of states of the two phases were calculated by using perturbation density function theory. Our calculated results showed that the energy level of x2-y2 orbital of V(3d) exhibits an separation in the electronic density of stats when VO2 transfer from metallic states to insulator state. The calculated equation of states of VO2 at zero temperature discovered a pressure-induced M—I phase transition at 68 GPa. The pressure-induced M—I phase transition can be due to the strong correlation between V(3d, 3s) and O(2p) orbital. Furthermore, based on the Gibbs free energy, we found that the temperature-induced phase transition is at 375 K. This is in agreement with the experimental result.