  During a crossover via a switching mechanism from one 2-body potential to
another as might be applied in modeling (chemical) reactions in the vicinity of
bond formation, energy violations would occur due to finite step size which
determines the trajectory of the particles relative to the potential
interactions of the unbonded state by numerical (e.g. Verlet) integration. This
problem is overcome by an algorithm which preserves the coordinates of the
system for each move, but corrects for energy discrepancies by ensuring both
energy and momentum conservation in the dynamics. The algorithm is tested for a
hysteresis loop reaction model with an without the implementation of the
algorithm. The tests involve checking the rate of energy flow out of the MD
simulation box; in the equilibrium state, no net rate of flows within
experimental error should be observed. The temperature and pressure of the box
should also be invariant within the range of fluctuation of these quantities.
It is demonstrated that the algorithm satisfies these criteria.
