Fig. 4.

Density of states (DOS) and corresponding accumulated oscillator strength of defective anatase TiO₂. a–c DOS of TiO₂ surface with 1O_v, 2O_v, and 4O_v per slab, respectively. d–f Oscillator strength of TiO₂ surface with 1O_v, 2O_v, and 4O_v per slab, respectively. The oscillator strength was calculated for transitions from gap states to conduction band (CB). The orange, blue, and light green area in the DOS stand for projected DOS of Ti⁴⁺ ions, Ti³⁺ ions, and O²⁻ ions, respectively. The gap state, valence band maximum (VBM), and conduction band minimum (CBM) are indicated in the DOS. Accumulated oscillator strength is calculated by summing the component data of y and z direction in Supplementary Fig. 24