Response of the hydrogen bond network to the ionization of bulk water: Ab initio molecular dynamic simulations using H₂S(aq)

Abstract The H₂S⁺ ligand was used to study the first proton-transfer (PT1) process in microsolvation and aqueous environments. The average time scale of PT1 of (H₂O)₃⁺ clusters (Δt_PT1 = 22.8 fs) was notably shorter than that of (H₂O)₂H₂S⁺ clusters at 79.5 fs. Compared with cationic-water clusters, the smaller potential energy gain observed in the H₂S-containing clusters was considered the dominant factor for such slow PT1 dynamics. Δt_PT1 of the [H₂S]⁺(aq) at 106.5 fs was significantly longer than the (H₂O)₂H₂S⁺ clusters. The stabilization effect resulting from the solvent reorientation and formation of H₂S⁺⋯¯OH₂ hemibond interactions was responsible for this delay.