Viscosity of liquid water from computer simulations with a polarizable potential model

The longitudinal and shear viscosity of water are calculated by molecular d ynamics simulation with a polarizable potential model at room temperature. To overcome the difficulty of evaluating directly the stress autocorrelatio n function of a system with intrinsically many-body forces, we have resorte d to the analysis of the wave-vector-dependent longitudinal and transverse- current correlation functions. In a memory function formalism, the generali zed viscosity can be evaluated as a function of the wave vector k. By extra polating to k=0, we find longitudinal and shear viscosity values in better agreement with the experimental value than the corresponding quantities eva luated by making use of a nonpolarizable potential model. This result point s out that for a realistic reproduction of transport quantities, it is cruc ial to take into account many-body contributions to the interaction potenti al.