Recent Advances in Accelerated Molecular Dynamics Methods

Many important materials processes take place on time scales that vastly  exceed the nanoseconds accessible to molecular dynamics simulation.  Typically,  this long-time dynamical evolution is characterized by a succession of  thermally activated infrequent events involving defects in the material.   Over the fifteen years, we have been developing a new class of methods, accelerated  molecular dynamics, in which the known characteristics of infrequent-event  systems are exploited to make reactive events take place more frequently,  in a dynamically correct way.  For certain processes, this approach has  been remarkably successful, offering a view of complex dynamical evolution  on time scales of microseconds, milliseconds, and sometimes beyond.  Examples  include metallic surface diffusion and growth, radiation damage annealing  in ceramics, and carbon nanotube dynamics.  After an introduction to these  methods, I will present some recent advances and results, and then describe  the major ongoing challenges and our current thinking on how to overcome them.