To interpret these results, Franck-Condon simulations based on electronic structure calculations were carried out. Results from ZrO2ˉH2O are shown in Figure and are very similar to those found for TiO2ˉH2O. For both species, the lowest energy anions and neutrals are the "chemisorbed" cisdihyrodroxy MO(OH)2 structures, with trans structures lying less than 10 meV higher. The barriers for cis-→trans conversion are calculated to be 0.100 and 0.091 eV for Ti and Zr, respectively. The "physisorbed" MO2ˉH2O structures are higher in energy by 2-3 eV. In light of these results, we will refer to these clusters from now on as MO(OH)2 0/ ˉ. While the TiO(OH)2 0/ ˉ complexes are planar, the ZrO(OH)2 0/ ˉ complexes are not, with dihedral angles of 23.0 and 29.2, respectively. This non-planarity has a significant effect on the cryo-SEVI spectra as discussed below.