Journal Article Research Support, Non-U.S. Gov't binding free energy perturbation AChE AutoDock Vina EC 3.4.23.- FEP FPL HIV Protease HIV Protease Inhibitors HIV-1 protease Ligands REP SMD binding affinity empirical parameter fast pulling ligand modified Vina nature of binding non-equilibrium molecular dynamics non-equilibrium work p16 protease, Human immunodeficiency virus 1 relative binding affinity replica exchange molecular dynamics rupture force screening soft-core potential steered molecular dynamics λUS