title: Application of the SCC-DFTB method to H+(H2O)6, H+(H2O)21, and H+(H2O)22.
abstract: The low-lying potential energy minima of the H(+)(H(2)O)(n), n = 6, 21, and 22, protonated water clusters have been investigated using two versions of the self-consistent-charge density-functional tight-binding plus dispersion (SCC-DFTB+D) electronic structure methods. The relative energies of different isomers calculated using the SCC-DFTB+D methods are compared with the results of DFT and MP2 calculations. This comparison reveals that for H(+)(H(2)O)(6) the SCC-DFTB+D method with H-bonding and third-order corrections more closely reproduces the results of the MP2 calculations, whereas for the n = 21 and 22 clusters, the uncorrected SCC-DFTB+D method performs better. Both versions of the SCC-DFTB+D method are found to be biased toward Zundel structures.
authors.affiliation: Department of Chemistry and Center for Molecular and Materials Simulations, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Choi
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Jordan
mesh_terms: D006860:Hydrogen Bonding; D009010:Monte Carlo Method; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water