This might be achieved by mimicking the native receptor-ligand interactions as closely as possible, thus minimally perturbing the fully-interacting complex while maximally restrict-ing the accessible configurational volume during decoupling. However, the extent to which this can be achieved is limited when restraining only six DoF. Hence, it may be desirable to use restraints which do couple the these internal and relative external degrees of freedom in order to accelerate convergence of the decoupling calculations. In this case, the restraints which do couple the these degrees of freedom should be released through simulation to those which do not (and the associated free energy change accounted for), or some degree of error must be tolerated in the calculation of ∆G o Release . Finally, the ideal restraints would lack instabilities, and would be simple to select in an easily automatable manner. 4,27,39