Elucidating the Electronic Structures of the Ground States of the VO2-/(0) Clusters: Synergism between Computation and Experiment

作者：Hendrickx Marc F A^*; Van Tan Tran

来源：Journal of Chemical Theory and Computation, 2014, 10(9): 4037-4044.

DOI：10.1021/ct500526m

Electronic structures of VO2 and its anion were investigated with density functional theory (DFT), complete active space second-order perturbation theory (CASPT2), and restricted coupled-cluster with single, double, and perturbative triple excitations (RCCSD(T)) computational quantum chemical methods. The results show that there is a near-degeneracy of the lowest B-3(1), (3)A(1), and (1)A(11) states of the anion. Therefore, the 532 and 193 nm photoelectron spectra of VO2 are interpreted by exploring these states as possible initial states. The anionic ground state was identified at the highest computational level, that is, RCCSD(T), as (3)B(11)allowing the X band to be assigned to the B-3(1) (->) (2)B(11)transition, while the lower intensity and lower binding energy X' and X '' features are ascribed to the (1)A(1) (->) (2)A(11) and (3)A(11)-> (2)A(11) ionizations, respectively. The latter assignment is different from the recently proposed assignment of the corresponding slow electron velocity-map imaging (SEVI) spectra. Further, the A band is suggested to be mainly the result of an ionization from B-3(11) to (2)A(1). For all these ionizations an electron is removed from a predominant metal orbital. The higher energy bands B and C on the contrary can be ascribed as electron detachments out of molecular orbitals largely located on the oxygen centers. More precisely, the B band is attributed to the ionizations from B-3(1) -> (4)(1)A(22)and (2)A(2), while the C band is proposed to originate from the B-3(1) ->(1) B-4(1) and B-3(1) ->(1) B-2(11) ionizations. The proposed novel assignment is further corroborated by calculating the FranckCondon factors, which largely agree with the experimental vibrational progressions of the SEVI spectra.

• 出版日期2014-9