Quantum proton transfer in hydrated sulfuric acid clusters; A Perspective from semiempirical path integral simulations

Sugawara, Shuichi*; Yoshikawa, Takehiro*; Takayanagi, Toshiyuki*; Shiga, Motoyuki   ; Tachikawa, Masanori*

We have carried out path integral molecular dynamics simulations for hydrated sulfuric acid clusters to understand acid-dissociation and hydrogen-bonded structural rearrangement processes in these clusters from a quantum mechanical viewpoint. We have found that the acid dissociation processes, first and second deprotonation, effectively occur in a hydrated cluster with a specific cluster size. The mechanisms of the proton-transfer processes were analyzed in detail and it was found that the distance between O in sulfuric acid and O in the proton-accepting water is playing an important role. We also found that the water coordination number of the proton-accepting water is important in the proton-transfer processes.