First-principles study on electronic structure of Sr2Bi2O5 crystal

► For the first time, the energy band structure of Sr2Bi2O5 crystal is elucidated on the basis of DFT-GGA calculation. ► For Sr2Bi2O5 crystal, the type of the optical transition, the characters of valence and conduction bands, and the band-gap energy are theoretically determined. ► Photocatalytic ability of Sr2Bi2O5 is explained on the basis of effective masses of electrons and holes and of the distorted local structure.