title: QM/MM dynamics of CH3COO(-)-water hydrogen bonds in aqueous solution.
abstract: Two combined QM/MM molecular dynamics (MD) simulations, namely, HF/MM and B3LYP/MM, in which the central CH(3)COO(-) and its surrounding water molecules were treated at HF and B3LYP levels of accuracy, respectively, using the DZV+ basis set, have been performed to investigate the characteristics of CH(3)COO(-)-water hydrogen bonds in dilute aqueous solution. Both HF/MM and B3LYP/MM simulations clearly indicate relatively strong hydrogen bonds between CH(3)COO(-) oxygens and their nearest-neighbor waters compared with those of water-water hydrogen bonds in the bulk. In addition, it is observed that first-shell waters are either "loosely" or "tightly" bound to their respective CH(3)COO(-) oxygen atoms, leading to large fluctuations in the coordination number, ranging from 2 to 5, with the prevalent value of 3. Among the HF and B3LYP methods for the description of the QM-treated region, the latter predicts slightly higher hydrogen-bond strength in the CH(3)COO(-)-water complex.
authors.affiliation: School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.
authors.forename: Apirak
authors.initials: A
authors.lastname: Payaka
authors.forename: Anan
authors.initials: A
authors.lastname: Tongraar
authors.forename: Bernd Michael
authors.initials: BM
authors.lastname: Rode
mesh_terms: D000085:Acetates / Q000737:chemistry*; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory; D012996:Solutions; D014867:Water / Q000737:chemistry*
chemical_list: D000085:Acetates; D012996:Solutions; D014867:Water