The low-lying singlet electronic excited states of ZrO2: A symmetry adapted cluster–configuration interaction (SAC–CI) study

Abstract

The ground electronic state [X1A1(S0)] and nine low-lying singlet excited states [21A1(S2), 11A2(S3), 21A2(S6), 11B1(S4), 21B1(S7), 31B1(S11), 11B2(S1), 21B2(S5), and 31B2(S8) states] of ZrO2 were studied using SAC–CI theory. The geometries of the nine electronic excited states were optimized at the SAC–CI/def2-SVP, SAC–CI/def2-SVPD, and SAC–CI/LANL2TZ(f) levels. The vertical excitation energies and adiabatic excitation energies of the selected electronic excited states were calculated by single-point calculations at the SAC–CI/def2-TZVPPD and SAC–CI/LANL2TZ(f) levels. Stable C2v structures for the 11B2, 21B2, 31B2, and 11A2 states and stable Cs structures for the 11B1(A″), 31B1(A″), and 21A1(A′) states were determined. For comparison, the unrestricted density functional theory (UBPW91) was also applied to study the X1A1, 11A2, 11B1, and 11B2 states.