Optimal structure and vibrational spectra of (H2O)(n)(+) (n=1,2)

ab initio geometry optimizations were performed on the (H2O)(n)(+)(n=1,2) system. Subsequent geometry optimizing calculations and analysis of frequencies had shown that the water dimer cation in the equilibrium structure could be regarded as a complex between an oxonium ion H3O+ and a hydroxyl radical OH. The present geometry optimizations were performed by a gradient method included in the Gaussian-92 program. The optimized geometry of (H2O)(+) at the MP2/6-311+G(d,p) level is in excellent agreement with the experiment results obtained by Dinelli.