Table 1.

Selected bond distances (Å), angles (°), and force constants (mdyn/Å, mdyn⋅Å) for the ferric Ht Cyt c active site

Fe(III) Cyt c	X-ray crystallography [Protein Data Bank (PDB) ID code 1YNR]	DFT structure BP86/LanL2DZ*	QCC-NCA force constants
Fe-NHis	2.1	1.967	1.239
Fe-SMet	2.4	2.449	0.930
Fe-NPyr (average)	2.0	2.004	1.760
NPyr-Fe-NPyr (average)	90.0	90.0	0.751
NHis-Fe-SMet-C	127.0	150.0	—