Number of “beads” to use in the Levy flight movement of the ring polymer.
User-specified length of snippet.
Choose the snip length to maximize sampling efficiency. The efficiency can be
estimated by the mean-square displacement between configurations, printed at
the end of the output file. This efficiency will typically, however, be a
trade-off between the mean-square displacement (length of statistical
correlations) and the number of beads moved. Only the moved beads require
recomputing the potential, i.e., a call to Q-Chem for the electronic energy.
(Note that the endpoints of the snippet remain fixed during a single move, so
beads are actually moved for a snip length of . For 1 or 2 beads in
the simulation, Cartesian moves should be used instead.)