Charge Separation Process in Water Clusters Containing HCl. Molecular Dynamics Study Using Semiempirical Hamiltonians

The acid dissociation of HCl in water clusters was studied using the PM3-MAIS model in a direct molecular dynamic simulations framework. Several trajectories for each cluster size were computed to improve the sampling on the potential energy surface and to increase the statistical significance of our study. We have analyzed the emergence of well-defined hydration structures around the ions and the effect they have on the charge separation process. Surface and bulk solvation situations are examined for both ions in terms of the competing circumstances for water molecules in the cluster. Our results show that the prevailing situation in all these clusters is a water mediated interaction between the ions. This situation is related to the significant interplay of several factors such as charge transfer occurring between the ions and their first hydration shells. Our results show that no significant charge redistribution occurs during the Eigen-Zundel transformation.