title: Electronic structure and quantum dynamics of photoinitiated dissociation of O2 on rutile TiO2 nanocluster.
abstract: The adsorption and photoinitiated dissociation of molecular oxygen on reduced rutile TiO2 nanocluster have been studied using a hybrid density functional theory (DFT)/time-dependent DFT approach and a time-dependent wavepacket dynamics method. Results show that the most favorable state for O2 at the bridging row O-vacancy site of TiO2 is O2(2-) with an orientation parallel to the surface. We find that its dissociation in the electronic ground state involves a spin forbidden intersystem crossing, and therefore has a large barrier along the reaction pathway. However, time-dependent wavepacket calculations reveal that the photoinitiated O2 dissociation on TiO2 is very fast via a direct mechanism on the excited states. The lifetime of excited O2 molecules is predicted to be about 266 fs. Non-adiabatic effects among the singlet electronic states are found to play an important role in the O2 dissociation whereas the spin-orbit effect is negligible. In addition, adsorption of two O2 molecules at an O-vacancy site shows that the second O2 molecule can stabilize the system by about 0.22 eV.
authors.affiliation: Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA. pdholabhai@lanl.gov
authors.forename: Pratik P
authors.initials: PP
authors.lastname: Dholabhai
authors.forename: Hua-Gen
authors.initials: HG
authors.lastname: Yu