Molecular orbital calculation for N-doped ZnO

The electronic structures of ZnO, Li-doped ZnO and N-doped ZnO are calculat ed using the discrete variational Xa: method on model clusters. For ZnO, it is found that the Zn-O bonding is not perfectly ionic but partially covale nt because of the hybridization between Zn 3d and O 2p orbitals in the vale nce band. When a Zn atom of the cluster is replaced with a Li atom, the wid th of the valence band is expanded than that of the ZnO cluster, and at the same time the energy gap between HOMO and LUMO decreases. On the other han d, the new energy states originating from N 2p orbitals in the energy gap a re formed for N-doped ZnO.