Fig. 2: Ab initio calculations.

a–c Calculated spin resolved density of states of Ni²⁺, Ni⁴⁺, and Ni³⁺, respectively for x = 0.0325. d Ni–O bond lengths for x = 0 and x = 0.0325, respectively. The doped hole is going to one of the Ni²⁺ sites around the Ca dopant, converting it to Ni³⁺ (see Supplementary Note 4 for full relaxed structures). e Schematic of density of states of Ni³⁺ of x = 0.0325.