Dynamics of proton recombination with NO3− anion in water clusters

Abstract

Recombination events of a proton with NO₃⁻ at (H₂O)₈clusters are studied by molecular dynamics, using “on-the-fly” reliable ab initio MP2 potentials. The main findings are: (1) the lifetime of the ions is less than 1.2 picoseconds; (2) the recombination step invariably involves H₃O⁺, not H₅O₂⁺; and (3) an essentially unique transition-state structure of H₃O⁺/NO₃⁻ for recombination is found in all cases. Proton migration involves both H₃O⁺ and H₅O₂⁺ species: Grotthuss and other mechanisms contribute.