Table 1.

RMS Energy Deviations (kcal/mol) from LMP2/cc-pVTZ(-f)//HF/6-31G** for Peptides.

Peptide	Original OPLS-AAa	PFF	OPLS-AA/La	MMFF94a
Tetrapeptide
Alanine	1.47	0.81	0.56
Dipeptides
Alanine	0.43	0.20	0.27
Serine	0.47	0.16	0.44/0.34	0.97
Phenylalanine	0.35	0.05	0.15	0.21
Cysteine	1.91	0.31	0.35	1.21
Asparagine	1.30	0.19	0.16	2.25
Glutamine	0.98	0.69	0.96	1.00
Histidine	0.79	0.90	0.96/0.72	1.60
Leucine	0.37	0.57	0.34/0.38	1.27
Isoleucine	0.88	1.04	0.38	0.66
Valine	0.39	0.14	0.08/0.16	1.01
Methionine	1.00	0.59	0.59	1.05
Proline	2.25	0.76	1.54
Tryptophan	0.56	0.63	0.50	0.83
Threonine	0.77	0.61	0.87	1.15
Tyrosine	0.35	0.25	0.39	0.28
Averageb	0.81	0.55	0.47	1.04

^aFrom ref. 8.

^bProline not included.