Table 2.

H∙∙∙O distances R(H∙∙∙O) in GB crystalline monohydrate, calculated using periodic DFT in the B3LYP/6-31G** and PBE-D3/6-31G** approximations, and intermolecular H-bond enthalpies, computed using Equation (1).

Fragment a	R(H∙∙∙O), Å		–ΔHHB, kJ/mol
	B3LYP	PBE-D3	B3LYP	PBE-D3
Water–GB interactions
O–H12∙∙∙O1	1.676	1.656	31.1	32.3
O–H13∙∙∙O2	1.649	1.633	32.7	33.7
O3∙∙∙H11–C	1.989	1.964	18.5	19.2
O3∙∙∙H2–C	2.277	2.258	12.2	12.5
O3∙∙∙H4–C	2.442	2.459	9.9	9.7
O3∙∙∙H8–C	2.481	2.475	9.4	9.5
O3∙∙∙H3–C	2.543	2.528	8.7	8.9
O3∙∙∙H7–C	2.665	2.531	7.6	8.9
O3∙∙∙H9–C	2.671	2.663	7.5	7.6
Total enthalpy			137.6	142.3
GB–GB interactions
O1∙∙∙H3–C	2.188	2.175	13.8	14.1
O1∙∙∙H5–C	2.522	2.486	8.9	9.4
O1∙∙∙H6–C	2.647	2.641	7.7	7.8
O1∙∙∙H7–C	2.527	2.518	8.9	9.0
O1∙∙∙H9–C	2.275	2.263	12.3	12.5
O1∙∙∙H10–C	2.205	2.201	13.5	13.6
O2∙∙∙H6–C	2.168	2.158	14.2	14.4
O2∙∙∙H8–C	2.630	2.628	7.9	7.9
O2∙∙∙H10–C	2.253	2.228	12.6	13.1
Total enthalpy			99.8	101.8

^a see Figure 5. The atomic number used is included in the CDC file 760253.cif of GB crystalline monohydrate [56].