Table 1.

ESP charges, spin population and formal oxidation numbers of metal centres and substrate water molecules in DFT–QM/MM models of the OEC of PSII, introduced in the text, in the S₁ and S₂ states.

	ESP charge		spin pop. (oxid. no.)
centre	S1	S2	S1	S2
Mn(4)	+1.35	+1.49	−3.80 (+3)	+3.79 (+3)
Mn(3)	+1.26	+1.59	+3.82 (+3)	−2.74 (+4)
Ca2+	+1.77	+1.56	+0.01 (+2)	0.00 (+2)
O(Wslow)a	−0.82	−0.96	−0.00 (−2)	+0.00 (−2)
O(Wfast)b	−0.90	−0.88	−0.05 (−2)	+0.06 (−2)

^aOxygen of W^slow ligated to Ca²⁺.

^bOxygen of W^fast ligated to Mn(4).