A combined ab initio and Franck–Condon factor simulation study on the photodetachment spectrum of HfO2−

Abstract

Restricted-spin coupled-cluster single-double plus perturbative triple excitation {RCCSD(T)} potential energy functions (PEFs) of the X[combining tilde]1A1 state of HfO2 and the X[combining tilde]2A1 state of HfO2- were computed, employing the quasi-relativistic effective core potential, ECP60MWB, and an associated contracted [13s6p6d4f3g2h] basis set designed for Hf, and the augmented correlation-consistent polarized valence quadruple-zeta (aug-cc-pVQZ) basis set for O. Based on the differences between the computed r0 and re geometrical parameters obtained from the PEF, and available experimentally derived r0 geometrical parameters of the X[combining tilde]1A1 state of HfO2, the experimental re geometrical parameters of the X[combining tilde]1A1 state of HfO2 were estimated as:-re(HfO)=1.7751 A and thetae(OHfO)=107.37 degrees. In addition, Franck-Condon factors for the HfO2 (X[combining tilde]1A1)+e<--HfO2- (X[combining tilde]2A1) electron detachment process, which include allowance for Duschinsky rotation and anharmonicity, were calculated using the computed RCCSD(T) PEFs, and were used to simulate the HfO2 (X[combining tilde]1A1)+e<--HfO2- (X[combining tilde]2A1) photodetachment band of HfO2-. Employing the estimated experimental re geometrical parameters of the X[combining tilde]1A1 state of HfO2 obtained in this work, the iterative Franck-Condon analysis (IFCA) procedure was carried out to optimize the geometrical parameters of the X[combining tilde]2A1 state of HfO2- until the simulated spectrum matched best with the experimental 355 nm photodetachment spectrum of W. Zheng, et. al., J. Phys. Chem. A, 1998, 102, 9129. The equilibrium geometrical parameters of X[combining tilde]2A1 state of HfO2- derived via the IFCA procedure are re(HfO)=1.823 A and thetae(OHfO)=111.5 degrees. Further calculations on low-lying triplet states of HfO2 gave adiabatic electronic energies (Te's) of, and vertical excitation energies (Tvert's) to, the ã 3B2, b[combining tilde]3B1, c[combining tilde]3A1 and d[combining tilde]3A2 states of HfO2 (from the X[combining tilde]1A1 state of HfO2), as well as electron affinities (EAs) and vertical detachment energies (VDEs) to these neutral states from the X[combining tilde]2A1 state of HfO2-.