Accelerated Molecular Dynamics Methods for Long-Time Simulations in Materials

Many important processes in materials and chemical systems are intrinsically atomistic in nature but involve timescales that span many orders of magnitude, thus exceeding what can be directly simulated using molecular dynamics. In this paper, dedicated to William A. Goddard III, we give a brief introduction to the accelerated molecular dynamics (AMD) methodology, which is aimed at this problem. AMD methods exploit the infrequent-event nature of the activated processes that typically comprise this long-time evolution. In favorable cases, these methods can predict state-to-state evolution that approximates what would result from an extremely long molecular dynamics simulation, and the most accurate of the methods can do this to arbitrary accuracy. We present some examples of applications of these methods and discuss the greatest ongoing challenge for the methods.