With NCMC in BLUES, we can vary the number of perturbation and propagation steps relative to the amount of standard MD in order to allow an adequate amount of relaxation in order to ensure reasonable acceptance without using so much relaxation that the approach becomes tremendously inefficient. Here, we tested this by measuring the acceptance ratio as a function of the amount of relaxation (Figure ), and found that the acceptance probability increases rapidly from around 100 NCMC switching steps up to 10000 NCMC switching steps, then begins increasing more slowly with further relaxation. Thus, here, we selected 10000 NCMC steps and 10000 MD steps per cycle as a reasonable choice in order to determine how much enhancement in sampling (and therefore efficiency) NCMC can provide relative to standard MD or MD with MC.