Does a diol cyclic urea inhibitor of HIV-1 protease bind tighter than its corresponding alcohol form? A study by free energy perturbation and continuum electrostatics calculations. - Lu Wang; Yong Duan; Pieter F. W. Stouten; George V. De Lucca; Ronald M. Klabe; Peter A. Kollman (J. Comput. Aided Mol. Des., 2001)