The potential of mean force (PMF) 21 is computed from partial radial distribution functions g(r) through the relation F (r) = -k B T (ln g(r) -ln g max ), where g max is the maximum of g(r) over r which is used to arbitrary enforce F (r) = 0 for the lowest free-energy minimum. The angular PMF is computed from the angle distribution P (θ) through the analog relation The PMF curves can highlight areas of the coordinate space where the RDF and bond angle distributions have very small, but nonzero, values.