1. A method for computer-aided molecule design, the method comprising: executing an adaptive sampling function and rapid minimization function, the rapid minimization function employing iterative fitting of multi-atomic subunits of a molecule, the multi-atomic subunits including subunits having a plurality of non-hydrogen atoms, the multi-atomic subunits being fitted by perturbing the location of the multi-atomic subunits, while keeping the coordinates of the constituent atoms of a given subunit fixed with respect to all of the other constituent atoms of that subunit, in a real-space direction that reduces potential energy; wherein the rapid minimization function perturbs the real-space position of the multi-atomic subunits by calculating a scaled force vector for the subunits' constituent atoms, and then solving for new coordinates for the constituent atoms using root mean square fitting onto the new coordinates, while still keeping the coordinates of the constituent atoms of each subunit fixed with respect to one another, the scaled force vectors resulting from non-bonded interactions with a receptor and from bonded interactions with neighboring subunits, and the scaled force vectors being scaled according to molecular mechanics contributions to resolve steric violations first, geometries that stretch or compress bond lengths second, bond angle distortions third, and alterations in torsion angles last; and wherein the adaptive sampling function and rapid minimization function are executed on a computer.