A Full-Dimensional Quantum Dynamical Study of the Vibrational Ground State of H3O2- and its Isotopomers

We investigated the effect of deuteration oil the vibrational ground,state of the hydrated hydroxide anion using a nine-dimensional quantum dynamical model for the case of J = 0. The propagation of the nuclear wave function has been performed With the multi-configuration time-dependent Hartree method which yielded zero-point energies for the normal and fully deuterated species in quantitative agreement with previous diffusion Monte Carlo calculations, According to the zero-point energy the isotopomers having the hydrogen atom in the bridging position are more stable by about 1 kJ/mol as compared to the deuterium case. This holds irrespective of the deuteration state of the two OH groups. We also report the secondary geometric isotope effect on the O-O distance upon replacing the H- by a D-bond. It amounts to a contraction by about 0.005 angstrom for the symmetric isotopomers and 0.009 angstrom in the asymmetric case.