. Author manuscript; available in PMC: 2026 Apr 15.

Published in final edited form as: J Chem Theory Comput. 2010 Sep 14;6(9):2896–2909. doi: 10.1021/ct900599q

Table 2.

Structure and Energetics of the Model O₂⁻-Bound SOR Active Site in Its Three Possible Spin States, as Obtained from DFT Plane-Wave Calculations, at the PBE and $PBE + U$ Levels, and from Hybrid-DFT Evaluations, Using the Indicated Functionals along with the 6–31+G* Basis Set for the Superoxide Radical Anion and the 6–31G* Basis Set for the Remaining Atoms

method	spin state	$d_{Fe-proximal O}$ (Å)	$d_{O - O}$ (Å)	$∠_{Fe - O - O}$ (deg)	energy (kcal/mol)
PBE	$S = \frac{1}{2}$	1.83	1.38	128.9	7.49
	$S = \frac{3}{2}$	1.85	1.37	129.2	−0.19
	$S = \frac{5}{2}$	1.91	1.38	142.8	0.00
$PBE + U$	$S = \frac{1}{2}$	2.08	1.35	127.5	45.36
	$S = \frac{3}{2}$	2.30	1.35	122.5	−0.41
	$S = \frac{5}{2}$	2.31	1.35	122.9	0.00
B3LYP	$S = \frac{1}{2}$	1.95	1.34	128.8	21.07
	$S = \frac{3}{2}$	2.20	1.34	125.5	0.33
	$S = \frac{5}{2}$	2.18	1.34	128.0	0.00
PBE0	$S = \frac{1}{2}$	1.96	1.32	127.7	34.37
	$S = \frac{3}{2}$	2.17	1.32	125.2	0.12
	$S = \frac{5}{2}$	2.17	1.32	126.7	0.00
B97-3	$S = \frac{1}{2}$	1.97	1.32	128.1	30.90
	$S = \frac{3}{2}$	2.23	1.33	126.9	23.48
	$S = \frac{5}{2}$	2.28	1.32	126.4	0.00
BHH	$S = \frac{1}{2}$	1.76	1.37	127.6	75.22 (SC = 13%)^a
		1.73	1.37	127.7	71.02 (SC=88%)^a
	$S = \frac{3}{2}$	2.25	1.30	125.7	37.24
	$S = \frac{5}{2}$	2.23	1.30	125.9	0.00

SC stands for spin contamination.