Methods of calculating a free energy of solubility for a compound in a solvent by computer operations include the following steps: (i) establishing, using a computer model, an initial state for a system including an aggregate of multiple molecules of the compound in a solvent; (ii) establishing, using the computer model, a final state of the system including a single molecule from the aggregate fully solvated in the solvent and separate from a transformed aggregate; (iii) transforming, using the computer model, the system from the initial state to the final state, via removing a first molecule of the compound from the aggregate to form the transformed aggregate and replacing the first molecule with solvent at the site of the first molecule; and (iv) calculating the free energy of the transformation between the initial and the final states, which determines the free energy of solubility for the compound.