Fig. 9. (a) The absolute contribution to the calculated free energy due to thermal expansion for all structures in the polymorph set, calculated at the melting point (T _m) as the difference between the quasi-harmonic (thermally expanded) and harmonic free energy, A ^QHA(T _m) – A ^HA(T _m). (b) The pairwise differences in contribution due to thermal expansion to the relative thermodynamic stability of polymorphs at their respective melting temperatures, Δ(A ^QHA(T _m) – A ^HA(T _m)). Distributions are shown for molecular crystals with predicted (blue) and experimental (green) melting points.