A combined ab initio and Franck–Condon simulation study of the photodetachment spectrum of

RCCSD(T) potential energy functions (PEFs) of the X ∼ 1 A 1 state of ZrO2 and the X ∼ 2 A 1 state of ZrO 2 - have been computed employing the fully relativistic ECP28MDF ECP and associated aug-cc-pwCVQZ basis set for Zr (aug-cc-pVQZ for O). These PEFs were used in variational calculations of anharmonic vibrational wavefunctions of the ground electronic states of ZrO2 and ZrO 2 - . Franck–Condon factors which include allowance of Duschinsky rotation between these two electronic states were then computed and used to simulate the photodetactment spectrum of ZrO 2 - . Excellent agreement between the simulated and observed spectra is obtained, confirming the reliability of the PEFs used.