Protonizable water model for quantum dynamical simulations

A new functional form for describing proton transfer and hydrogen bond potential energy functions in condensed phase simulations is presented. Rather than fitting a potential energy function to ab initio or experimental potential energy profiles, monopole-dipole interactions are used as proton-protolyte pair potential, and Lennard-Jones functions with variable sigma- and epsilon-parameters are used to represent protolyte-proton-protolyte three body interactions. The number of parameters increases linearly with the number of protonizable molecule or molecular fragment types, and only eight parameters are needed per protonizable molecule or molecular fragment type. A parameter set for protonizable SPC/E water is presented, and the results of molecular dynamics (MD) and mixed quantum dynamics (QD)/MD simulations are discussed.