Potential energy landscape for proton transfer in (H2O)3H+: comparison of density functional theory and wavefunction-based methods

Predictions of the BLYP density functional are compared with wavefunction-based calculations for several structural and dynamical properties of (H2O)3H+. We focus attention on properties important for proton transfer in this cluster. Good agreement between density functional theory (DFT) calculations and all-electron MP2 results is found for energies, structures, and vibrational properties of both transition states and stable states. Good agreement between DFT and MP2 results is also observed for the potential experienced by the transferring proton in the transition state region. Structural predictions of empirical models compare well with the ab initio results.