Quantum mechanical/molecular mechanical molecular dynamic simulation of zinc(II) ion in water

The hydration structure of the Zn(II) ion has been studied by classical molecular dynamics (CMD) and quantum mechanical/molecular mechanical molecular dynamics (QM/MM-MD) simulations, using newly constructed ab initio two-body potentials and a three-body correction function. The average first-shell hydration structure is a 6-coordinate octahedron, and the structure parameters obtained by the QM/MM-MD simulation are in reasonable agreement with the experimental values. The first-shell angular distribution functions show a satisfactory consistency for both simulations, suggesting that the classical potential functions well describe the O-Zn-O angular distortion in the CMD simulation, while the quantum mechanical treatment of the Zn(II) ion and its first hydration shell in the QM/MM-MD simulation increases the tilting probability of the coordinating H2O molecules. Dynamic properties such as vibrational and rotational motions of water molecules were evaluated using velocity autocorrelation functions (VACFs).