A theoretical study of (1010) and (0001) ZnO surfaces: molecular cluster model, basis set and effective core potential dependence

Abstract

Ab initio calculations at different basis set levels and effective core potentials (ECPs) have been carried out for (ZnO) n . n = 3, 4, 6 and n = 5 molecular cluster models of (100) and (0001) zinc oxide surfaces, respectively. Net atomic charges, force constants, geometrical variables and orbital energy levels are analyzed, discussed and compared with previous theoretical and experimental data The calculated orbital levels for the different cluster models are compared with reported experimental ultraviolet photoelectron spectroscopy (UPS) data. The results can be summarized as follows, (i) The double zeta basis set or the Stevens ECP (W.J. Stevens, H. Basch and M. Krauss, J. Chem. Phys., 81 (1984) 6026) representation for the oxygen atom in the different molecular model clusters improves the results slightly. However, there is a strict dependence on the valence double zeta basis set or minimum basis set used for the zinc atom, (ii) The theoretical description of the UP spectrum is dependent on the size of the molecular cluster model.