EXAMINING THE INFLUENCE OF THE [ZN(H2O)(6)](2-CARLO SIMULATIONS OF ZN2+ IN WATER() GEOMETRY CHANGE ON THE MONTE)

Quantum chemical calculations have been carried out to estimate the va riation in the interaction energy between one or two water molecules a nd the Zn2+ hydrated ion ([Zn(H2O)(6)](2+)) when the Zn-O intramolecul ar distance is changed. Likewise, changes in the interaction energy be tween a second hydration shell formed by twelve H2O and the hydrated i on when shrinking the hexahydrate have been also examined, using a pre viously reported hydrated ion-water potential [Pappalardo et al., J. P hys. Chem. 97, 4500 (1993)] and the Matsuoka-Clementi-Yoshimine (MCY) potential for the water-water interactions. Using these potentials and that of Clementi for the Zn2+-H2O interaction, Monte Carlo simulation s have been performed using two different Zn-O distances for the first hydration shell. Results show that influence of the geometrical relax ation on the solvation energy is not large, about 2.5%. Consequences o n the use of a flexible or rigid hydrated ion are discussed. (C) 1996 American Institute of Physics.