Na(+), K (+) and Tl(+) hydration from QM/MM computations and MD simulations with a polarizable force field

The hydration of three different monovalent cations was studied with a number of theoretical approaches ranging from classical MD simulations to MD simulations with a polarizable force field and finally to QM/MM MD. A particular emphasis was put on the development of a novel polarizable potential function for studies of Tl(+) hydration enabling the ability to reproduce key features observed in QM/MM simulations. We extended the CHARMM-deMon interface developed previously to studies of ion hydration with QM/MM simulations. All simulations reproduce experimental data on the Radial Distribution Function (RDF) accurately. However, notable differences start to emerge in the description of probabilities for coordination states of an ion if explicit account of polarization is included.