Regime Switching Issues and Criteria for Coupled Static-Dynamic Atomistic Methods

摘要

Coupled static-dynamic atomistic method may be used for coarse graining time in temporal multi-scale atomistic modeling of nano-mechanical problems. This approach can be especially effective for mechanical processes that consist of two distinct phases: the slow phase when the system resides in one local energy minimum and the fast phase associated with a rapid transition from one meta-stable state to another. In this case, the slow phase can be effectively modeled using static energy minimization technique, while the fast phase corresponding to the state transition event may be modeled dynamically. In this case, dynamic modeling is necessary to capture the dynamic effects, such as thermal and inertial, that can not be accounted for in static modeling. One of the major issues of this type of method is to determine when the transitions between the two regimes have to be done. In this presentation, issues of switching between the static and dynamic regimes are outlined and criteria that can be used for effective switching between the two regimes are proposed. In particular, a dynamic-to-static switch based on the kinetic energy and static-to-dynamic switch based on the potential energy are discussed.