Coupling molecular dynamics with amorphous cells for polymer modeling

Abstract

A method to reduce the degrees freedom in molecular mechanics simulation is presented. Although the approach is formulated for amorphous materials in mind, is equally applicable to crystalline materials. The method can be selectively applied to regions where molecular displacements are expected to be small while simultaneously using classical molecular mechanics for regions undergoing large deformation. The accuracy and computational efficiency of the approach is demonstrated through the simulation of a polymer-like substrate being indented by a rigid hemispherical indentor. The region directly below the indentor is modelled by classical molecular mechanics while the region further away has the degrees of freedom reduced by about 50 times. Comparisons of substrate strain and indentation force versus depth curves with full molecular mechanics simulation show that both sets of results are almost identical.