First principles studies of the electronic and structural properties of the rutile VO2(110) surface and its oxygen-rich terminations.

We present a density functional theory (DFT) study of the structural and electronic properties of the bare metallic rutile VO2(110) surface and its oxygen-rich terminations. Due to the polyvalent nature of vanadium and abundance of oxide phases, the modelling of this material on the DFT level remains a challenging task. We discuss the performance of various DFT functionals, including PBE, PBE +U(U= 2 eV), SCAN and SCAN + rVV functionals with non-magnetic and ferromagnetic spin ordering, and show that the calculated phase stabilities depend on the chosen functional. We predict the presence of a ring-like termination that is electronically and structurally related to an insulating V2O5(001) monolayer and shows a higher stability than pure oxygen adsorption phases. Our results show that employing the spin-polarized SCAN functional offers a good compromise, as it offers both a reasonable description of the structural and electronic properties of the rutile VO2bulk phase and the enthalpy of formation for oxygen rich vanadium phases present at the surface.