  We present a dual-resolution molecular dynamics (MD) simulation of liquid
water employing a recently introduced Adaptive Resolution Scheme (AdResS). The
spatially adaptive molecular resolution procedure allows for changing from a
coarse-grained to an all-atom representation and vice-versa on-the-fly. In
order to find the most appropriate coarse-grained water model to be employed
with AdResS we first study the accuracy of different coarse-grained water
models in reproducing the structural properties of the all-atom system.
Typically, coarse-grained molecular models have a higher diffusion constant
than the corresponding all-atom models due to the reduction in degrees of
freedom (DOFs) upon coarse-graining that eliminates the fluctuating forces
associated with those integrated-out molecular DOFs. Here, we introduce the
methodology to obtain the same diffusional dynamics across different
resolutions. We show that this approach leads to the correct description of
essential thermodynamic, structural and dynamical properties of liquid water at
ambient conditions.
