title: Dynamical discrete/continuum linear response shells theory of solvation: convergence test for NH4+ and OH- ions in water solution using DFT and DFTB methods.
abstract: A new dynamical discrete/continuum solvation model was tested for NH(4)(+) and OH(-) ions in water solvent. The method is similar to continuum solvation models in a sense that the linear response approximation is used. However, different from pure continuum models, explicit solvent molecules are included in the inner shell, which allows adequate treatment of specific solute-solvent interactions present in the first solvation shell, the main drawback of continuum models. Molecular dynamics calculations coupled with SCC-DFTB method are used to generate the configurations of the solute in a box with 64 water molecules, while the interaction energies are calculated at the DFT level. We have tested the convergence of the method using a variable number of explicit water molecules and it was found that even a small number of waters (as low as 14) are able to produce converged values. Our results also point out that the Born model, often used for long-range correction, is not reliable and our method should be applied for more accurate calculations.
authors.affiliation: Grupo de Pesquisa em Química Inorgânica Teórica (GPQIT), Departamento de Química, ICEx, Universidade Federal de Minas Gerais, 31270-901, Belo Horizonte, MG, Brazil.
authors.forename: Guilherme Ferreira
authors.initials: GF
authors.lastname: de Lima
authors.forename: Hélio Anderson
authors.initials: HA
authors.lastname: Duarte
authors.forename: Josefredo R
authors.initials: JR
authors.lastname: Pliego
mesh_terms: D006878:Hydroxides / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012996:Solutions; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D007477:Ions; D000644:Quaternary Ammonium Compounds; D012996:Solutions; D014867:Water