Error Estimate of Short-Range Force Calculation in the Inhomogeneous Molecular Systems

Abstract

In the present paper, we develop an accurate error estimate of the non-bonded short-range interactions for the inhomogeneous molecular systems. The root mean square force error is proved to be decomposed into three additive parts: the homogeneity error, the inhomogeneity error and the correlation error. The magnitude of the inhomogeneity error, which is dominant in the interfacial regions, can be more than one order of magnitude larger than the homogeneity error. This is the reason why a standard simulation with xed cut-off radius is either less accurate if the cut-off is too small, or wastes considerable computational effort if the cut-off is too large. Therefore, based on the error estimate, the adaptive cut-off and long-range force correction methods are proposed to boost the efficiency and accuracy of the simulation, respectively. The effectiveness of the proposed methods are demonstrated by molecular dynamics simulations of the liquid-vapor equilibrium and the nanoscale particle collision. Different roles of the homogeneity error and inhomogeneity error are also discussed.