  Metastability is a common obstacle to performing long molecular dynamics
simulations. Many numerical methods have been proposed to overcome it. One
method is parallel replica dynamics, which relies on the rapid convergence of
the underlying stochastic process to a quasi-stationary distribution. Two
requirements for applying parallel replica dynamics are knowledge of the time
scale on which the process converges to the quasi-stationary distribution and a
mechanism for generating samples from this distribution. By combining a
Fleming-Viot particle system with convergence diagnostics to simultaneously
identify when the process converges while also generating samples, we can
address both points. This variation on the algorithm is illustrated with
various numerical examples, including those with entropic barriers and the 2D
Lennard-Jones cluster of seven atoms.
