To validate NCMC with MD for sidechain rotations, we tested our method on a simple model system and compared it with brute force MD as well as umbrella sampling. Ultimately, we were interested in whether our BLUES with sidechain rotations produces correct rotamer populations consistent with those obtained from umbrella sampling. Given the structure and a list of residue ID numbers, BLUES identifies significant rotatable bonds in those residues; these are bonds for which neither terminus is a hydrogen. It also identifies all upstream atoms that would move as a result of each significant bond being rotated. This information is compiled and stored in a dictionary. Thereon, BLUES cycles through a series of steps as it executes n NCMC sidechain rotation move proposals (shown in the dashed box). First a bond is randomly selected from the dictionary. If the angle falls within one of the rotamer bins (as described in Figure ), a move to a new rotamer bin is proposed and executed via the NCMC protocol (represented by green path). Otherwise (yellow path), the sidechain move proposal is skipped and an additional round of molecular dynamics is executed before restarting the cycle by randomly selecting a bond.