Preferential Solvation and Dynamics of Ions Solvated in Mixed Solvents: Insights from QM/MM MD Simulation Approach

摘要

Ab initio QM/MM molecular dynamics simulations have been performed to obtain detailed information on the preferential solvation and dynamics of ions in aqueous ammonia solution. The most interesting region, i.e., the mixed-ligand solvates, was treated by Hartree-Fock method using LANL2DZ basis sets, while the rest of the system was described by classical pair potentials. The QM/MM results clearly show the effects of many-body interactions on the geometrical arrangement as well as on the coordination number of the solvated ions. The preference for ligand molecules is discussed on the basis of detailed simulation results. According to dynamics of the ion solvates, in particular K~+, a "structure-breaking" behavior of the ion is well recognized by the detailed analysis on ligand exchange processes and the mean residence times of the ligands surrounding the ion.