AB-INITIO STUDIES ON THE STRUCTURES AND VERTICAL ELECTRON DETACHMENT ENERGIES OF COPPER-WATER NEGATIVE-ION CLUSTERS CU-(H2O)N AND CUOH-(H2O)N-1

The equilibrium geometries of Cu-(H2O)n and CuOH-(H2O)n-1 (n=1 and 2) negative ion clusters have been optimized by performing ab initio calculations at the second-order Moller-Plesset (MP2) approximation with extended basis sets. For comparison, the geometries of X- (H2O)n (X=F, Cl, Br and I) are optimized at the same level of approximation. The calculated results show that all hydrogen atoms in the equilibrium geometries of Cu-(H2O)n (n=1 and 2) are equivalent to each other, which is contrasted to the geometries of X-(H2O)n, where one of the hydrogens of H2O is more strongly bonded to X-. The calculated vertical electron detachment energies as well as hydration energies with MP4SDTQ are very close to the corresponding experimental data.