Ground state structure of CuO2: a CASPT2 study

The ground state structure of CuO2, which has been discussed extensively in the literature, has been determined using a multiconfigurational SCF metho d and second-order perturbation theory. In the gas phase, it has been found to have a side-on C-2v structure. However, when introducing effects of a s urrounding matrix, the ground state changes to an end-on C-s structure, wit h an energy 1.2 kcal/mol lower than the side-on structure. Computed harmoni c frequencies are in agreement with experiment. MRSDCI calculations have al so been performed and they confirm the results obtained at the second-order perturbation theory level. Previous density functional theory studies have failed to predict a correct ground state structure. (C) 2001 Elsevier Scie nce B.V. All rights reserved.