VACANCY MIGRATION RATES BY MOLECULAR-DYNAMICS WITH CONSTRAINTS

Rate constants for vacancy migration in a Lennard-Jones crystal are evaluated within the frame of the reactive flux correlation function formalism by molecular dynamics simulation. In our calculation a key role is played by a holonomic constraint acting on the reaction coordinate. The definition of a suitable reaction coordinate is a subtle matter as becomes evident when using our techniques. We show bow the ambiguities in the definition of the reaction coordinate can be circumvented. Our results are two orders of magnitude more precise than previous 'exact' calculations.