Table 2: Calculated interaction energy without correction ( , kcal/mol), BSSE-corrected energy of hydrogen bond formation using counterpoise correction ( , kcal/mol), hydrogen bond numbers for TMG + n water complex ( ), TMG dimer, and water dimer using 6-31++G(d,p) basis set and various methods.

Systems Calculation methods No. of hydrogen
bonds

MP2−7.65−5.62
HF−5.64−4.94
B3LYP−6.71−5.77
TMG + 1 water complex (TD)B3LYP DFT-D−7.79−6.812
WB97XD−7.42−6.51
M06−7.00−6.15
M062X−7.59−6.63

MP2−7.46−4.93
HF−4.71−3.88
B3LYP−5.38−4.58
TMG + 1 water complex (WD)B3LYP DFT-D−8.92−7.843
WB97XD−8.01−7.01
M06−7.39−6.46
M062X−8.48−7.37

MP2−16.39−11.30
HF−10.80−9.24
B3LYP−13.46−11.44
TMG + 2 water complex
B3LYP DFT-D−18.32−16.104
WB97XD−16.91−14.81
M06−16.33−14.19
M062X−17.90−15.51

MP2−9.46−5.51
HF−4.52−3.51
B3LYP−7.58−6.61
TMG dimerB3LYP-DFTD−13.38−12.264
WB97XD−9.96−8.90
M06−14.69−13.68
M062X−15.18−13.87

MP2−6.39−4.83
HF −5.01−4.36
B3LYP−5.97−5.19
Water dimerB3LYP-DFTD−6.71−5.951
WB97XD−6.35−5.61
M06−5.99−5.25
M062X−6.58−5.80