Table 4. Experimental ¹H Chemical Shifts and the Corresponding Calculated NMR Shieldings in ppm.

	hydrogen	δexpa	PBEb	TPSSb	B3LYPb	DLPNO-DSD-PBEP86c	DLPNO-MP2c
l-alanine	H-α	3.82	26.91	27.28	27.23	27.23	27.09
	NH3	8.5	22.15	22.57	22.25	22.18	22.04
	H-β	1.38	29.43	29.81	29.67	29.63	29.52
α-glycine	NH3	8.48	22.35	22.81	22.46	22.39	22.25
	H-α1	4.23	26.53	26.91	26.78	26.78	26.67
	H-α2	3.06	27.51	27.90	27.79	27.79	27.69
l-serine	H-α	3.64	27.05	27.41	27.42	27.43	27.32
	H-β1	3.75	27.03	27.45	27.38	27.34	27.21
	H-β2	4.46	26.28	26.75	26.67	26.66	26.51
	NH3	8.37	22.37	22.84	22.50	22.43	22.30
	OH	3.79	27.49	27.89	27.55	27.34	27.10
l-aspartic acid	COOH	15.57	15.00	15.45	14.96	14.81	14.58
	H-β1	3.27	26.86	27.33	27.21	27.21	27.09
	H-β2	2.54	27.73	28.13	28.00	28.01	27.81
	NH3	8.32	22.70	23.11	22.82	22.80	22.63
	H-α	3.76	27.56	27.95	27.90	27.87	27.69
l-cysteine	H-β1	3.55	27.44	27.90	27.80	27.82	27.69
	H-β2	2.78	28.11	28.50	28.50	28.43	28.23
	H-α	4.28	26.74	27.13	27.10	27.14	27.00
	NH3	8.65	22.24	22.70	22.36	22.34	22.20
	SH	1.92	28.09	28.57	28.46	28.32	28.19
l-threonine	NH3	8.03	22.62	23.07	22.77	22.72	22.53
	H-α	4.02	26.79	27.17	27.11	27.11	26.93
	H-β	3.78	26.86	27.31	27.29	27.26	27.08
	OH	7.95	22.39	22.84	22.44	22.31	22.17
	H-γ	1.39	29.53	29.92	29.78	29.69	29.59

^aExperimental values from ref (18).

^bValues calculated using the scheme described in Section 2.2 with pcSseg-3 and pcSseg-2 basis sets for QM1 and QM2, respectively.

^cpcSseg-3 and def2-TZVP basis sets for QM1 and QM2, respectively, were used, and NormalPNO and LoosePNO settings using the fragment scheme presented in Section 2.2 were used.