Probing the structural and electronic properties of small vanadium dioxide clusters by density functional theory and comparison with experimental photoelectron spectroscopy

摘要

The structural evolution and bonding of a series of early transition-metal dioxide clusters, V_ nO_ 2~ q(n=3-9, q=0, -1), have been investigated using density functional theory (DFT) calculations and the results are compared with experimental literature data. For each vanadium dioxide cluster, many low-lying isomers are generated using the Saunders Kick global minimum stochastic search method. Theoretical electron detachment energies (both vertical and adiabatic) were compared with the experimental measurements to verify the ground states of the vanadium dioxide clusters obtained from the DFT calculations. Five kinds of dissociative adsorption configurations of ground-state structure ofV_ nO_ 2~ qare identified. The dissociative adsorption of O_ 2 on V_ n~ (-1),~ 0 is more favorable than O_ 2 molecular adsorption. Furthermore, the adsorption energy of O_ 2 is higher than that of a single atom on the bare V_ n~ (-1),~ 0 clusters, but less than twice the adsorption energy for an atom, indicating that O_ 2 being adsorbed on vanadium clusters are more difficult than single O atom adsorbed on vanadium clusters.