  Recently a non-empirical stochastic walker algorithm has been developed to
search for the minimum-energy escape paths (MEP) from the minima of the
potential surface [J. Phys. Soc. Jpn. 87, 063801 (2018)]. This algorithm is
novel in that it tracks the MEP monotonically and does not use the whole
Hessian matrix but only gradient and Laplacian of the potential. In this work,
we implement an MPI-parallelized version of this algorithm in a simple way. We
also explore efficient ways to reduce the number of walkers required for the
accurate tracking of the MEP and generate initial positions automatically. We
apply the whole scheme to the Lennard-Jones argon cluster with 7-38 atoms to
demonstrate the successful tracking of the reaction paths. This achievement
paves the path to non-empirical simulation of rare reactions without
coarse-graining or artificial potential.

Statistical Mechanics;Materials Science;Chemical Physics