B3LYP Study on Reduction Mechanisms from O₂ to H₂O at the Catalytic Sites of Fully Reduced and Mixed-Valence Bovine Cytochrome 𝑐 Oxidases

Table 2

Total energies (au), expectation values of square of spin angular momentums (au), and relative energies (kcal/mol) of optimized intermediates.

Intermediates	(C,2S+1)^a	𝐸total	⟨𝑆^2⟩	Δ𝐸rel
1	(1, 3)	−5548.568706	2.1488
2	(1, 1)	−5698.927805	0.9297	0.0	26.7^b
	(1, 3)	−5698.922264	2.0241	3.5
3	(2, 1)	−5699.226658	0.9388	0.0
4	(2, 1)	−5699.280053	1.0223	−33.5
5	(3, 1)	−5699.492987	1.0247	0.0
6	(3, 1)	−5699.501523	1.0280	−5.4
7	(3, 1)	−5699.526079	2.0580	−20.8
8	(0, 2)	−5699.056867	0.7749	81.0^c	60.5^d
9	(1, 2)	−5699.450706	0.7843	0.0
10	(1, 2)	−5699.538816	0.7663	−55.3
11	(2, 2)	−5699.846714	0.7672	0.0
12	(2, 2)	−5699.870050	0.7720	−14.6
12a	(2, 2)	−5699.866225	0.7715	−12.2
13	(2, 2)	−5699.906221	1.7773	−37.3
14	(2, 2)	−5776.364920	1.7725
15	(1, 3)	−5776.635143	2.0192
16	(2, 3)	−5777.019546	2.0295
17	(3, 3)	−5777.261791	2.0402
18	(3, 3)	−5624.389728	2.2087
19	(2, 4)	−5624.742138	3.8743

a(C, 2S+1) means (total charge, spin multiplicity).
bO₂-binding energy: Δ𝐸_rel = E(𝟐) − E(𝟏) − E(O₂).
cElectron affinity of 2: Δ𝐸_rel = E(𝟐) − E(𝟖).
^dO₂⁻-binding energy: Δ𝐸_rel = E(𝟖) − E(𝟏) − E(O₂⁻).