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 presente d. Rather than fitting a potential energy function to ab initio or exp erimental potential energy profiles, monopole-dipole interactions are used as proton-protolyte pair potential, and Lennard-Jones functions w ith variable sigma- and epsilon-parameters are used to represent proto lyte-proton-protolyte three body interactions. The number of parameter s increases linearly with the number of protonizable molecule or molec ular fragment types, and only eight parameters are needed per protoniz able molecule or molecular fragment type. A parameter set for protoniz able SPC/E water is presented, and the results of molecular dynamics ( MD) and mixed quantum dynamics (QD)/MD simulations are discussed.