Monte Carlo integration yielded A E M , the free energy of the Einstein molecule, as it was previously done for α-methanol in the literature . ∆A id→I E M and ∆A I E M →solid were estimated using Thermodynamic Integration (TI) and the Multistate Bennett Accep-tance Ratio (MBAR) . We used force constants of 4000 k B T/Å 2 to restrain atoms to their lattice positions in acetylsalicylic acid and argon simulations because it allowed us to use a reasonable time step of 1.0 fs in all simulations. α-methanol simulations used the same force constant that had been previously used by Aragonès et al. .