Space-time correlated reaction field: A stochastic dynamical approach to the dielectric continuum

Abstract

In molecular dynamics (MD) simulations, the continuum description of electrostatic interactions has been based in most cases on the static response of the dielectric continuum. In this work, a time-dependent reaction field expression including stochastic and friction terms is derived in analogy to the generalized Langevin equation involving hydrodynamic interactions. Simulations of water using the extended simple-point charge model have been performed under different boundary conditions. The effects of a time-dependent treatment of the reaction field are demonstrated by comparing the results to those of MD simulations using a static, instantaneous reaction field and of MD simulations employing the Ewald sum. It is shown for the first time that the straight cutoff approach not only leads to a disruption of the time, but also of the spatial correlation of the dipole moment.