First-Principles Band Calculations on Electronic Structures of Ag-Doped Rutile and Anatase TiO₂

The electronic structures of Ag-doped rutile and anatase TiO₂ are studied by first-principles band calculations based on density functional theory with the full-potential linearized-augmented-plane-wave method. New occupied bands are found between the band gaps of both Ag-doped rutile and anatase TiO₂. The formation of these new bands can be explained mainly by their orbitals of Ag 4d states mixed with Ti 3d states and are supposed to contribute to their visible light absorption.