Influence of interstitial beryllium on properties of ZnO: A first-principle research

► The doping of Be atom at interstitial positions of ZnO is energetically favorable. ► Interstitial Be atoms would decrease the band gap of ZnO. ► Changes of band gap are due to the increase of covalent and metallic bonding. ► The present results could clarify the controversies of ZnBeO in the literature.