Accelerated Molecular Dynamics Methods

Friday, July 27, 2007 - 2:00pm - 2:40pm
Arthur Voter (Los Alamos National Laboratory)
A significant problem in the atomistic simulation of materials is that
molecular dynamics simulations are limited to nanoseconds, while important
reactions and diffusive events often occur on time scales of microseconds
and longer. Although rate constants for slow events can be computed directly
using transition state theory (with dynamical corrections, if desired,
to give exact rates), this requires first knowing the transition state.
Often, however, we cannot even guess what events will occur. For example,
in vapor-deposited metallic surface growth, surprisingly complicated exchange
events are pervasive. I will discuss our accelerated molecular dynamics approach
for treating this problem of complex, infrequent-event processes. The idea is to directly
accelerate the dynamics to achieve longer times without prior knowledge
of the available reaction paths. With these methods, we can often achieve accurate dynamical
evolution on time scales exceeding that available to direct molecular dynamics by many orders
of magnitude. Time permitting, I will also discuss some of our most recent method