Table 4. Lattice energy (ΔE at 0 K) or free energy (ΔG at 300 K) difference relative to coumarin I in kJ mol^{–1 a} .

	PBE(0)+MBD		OPLS
Polymorph	ΔE	ΔG (harmonic)	ΔE	ΔG (harmonic)	ΔG (anharmonic)
Coumarin II	0.27	0.70	1.58	2.02	4.5 ± 0.7
Coumarin III	1.21	0.94	4.17	2.73	n/d
Coumarin IV	1.78	0.90	3.72	1.47	n/d
Coumarin V	2.18	0.17	5.47	4.22	16.0 ± 1.6

^a“n/d” – not determined.