Since solids are much less susceptible to volume changes than liquids, it is reasonable to consider that P∆V is negligible and ∆G ≈ ∆A. For instance, the difference in volume between the experimental ASA crystal structure and the simulation box after a constant pressure equilibration stage is 0.14 nm 3 . The P∆V term -i.e., the free energy difference discounting possible structure relaxation effects -would be much smaller than the simulation error.