POLARIZATION AND DYNAMICAL CHARGE OF ZNO WITHIN DIFFERENT ONE-PARTICLE SCHEMES

We calculate ab initio the electronic states, spontaneous polarization P, and Born dynamical charge Z of ZnO, using the local-density appro ximation (LDA), the Hartree-Fock (HF), and a model GW scheme. Upon goi ng from HF to GW and to LDA, the d bands raise substantially in energy , the model GW providing the best overall agreement with experiment. B y contrast, the three schemes give the concordant values P=-0.047 C/m( 2) and Z=+/-2.1, in agreement with available experimental data. While the value of Z suggests a rigid-ion-like behavior of ZnO, its band-b y-band decomposition reveals anomalous contributions from O 2s, Zn 3d, and O 2p bands, indicating a substantial interaction between the corr esponding occupied atomic orbitals.