Ab initio study of metal-insulator transition in VO2

The structure distortion accompanied metal-insulator transition (MIT) of vanadium dioxide (VO$_2$) at 340K has been a matter of ongoing controversy for near four decades. It is still unclear whether the nature of this transition is due to a Peierls instability, a Mott-Hubbard transition, or other physics. Most density functional theory based methods fail to describe the nature of the electronic state in this system, further complicating theoretical description of VO$_2$. We will report on progress in applying the first principles diffusion quantum Monte Carlo method to the electronic structure of VO$_2$ in the metallic and insulator phases. By examining the energetic properties, one particle reduced density matrix, as well as other static correlations in the two phases of the system, we will comment on which of the two common descriptions is a closer representation of the physical reality of VO$_2$.