Study of Cl(-)(H2O)n (n = 1-4) using basin-hopping method coupled with density functional theory.

Cl(-)(H2O)n (n = 1-4) clusters were investigated using a basin-hopping (BH) algorithm coupled with density functional theory (DFT). Structures, energetics, thermodynamics, vertical detachment energies, and vibrational frequencies were obtained from high-level ab initio calculations. Through comparisons with previous theoretical and experimental data, it was demonstrated that the combination of the BH method and DFT could accurately predict the global and local minima of Cl(-)(H2O)n (n = 1-4). Additionally, to optimize larger Cl(-)(H2O)n (n > 4) clusters, several popular density functionals as well as DF-LMP2 (Schütz et al., J. Chem. Phys. 2004, 121, 737) (second-order Møller-Plesset perturbation theory using local and density fitting approximations) were tested with appropriate basis sets through comparisons with MP2 optimized results. DF-LMP2 will be used in future studies because its overall performance in describing the relative binding energies and the geometrical parameters of Cl(-)(H2O)n (n = 1-4) was outstanding in this study.