First-principles study on the electronic and bonding properties of PbTiO₃ (110) polar terminations

The electronic structures and bonding properties of the (110) polar terminations of cubic PbTiO₃ were examined by the first-principles calculations at the generalized gradient approximation level. Two stoichiometric (PbTiO and O₂) and three nonstoichiometric(TiO, Pb, and O) terminations were considered in this study. With the aid of the calculated electron density differences, atomic charges, band structures, and densities of states, the charge redistributions and electronic properties were evaluated in detail. Furthermore, based on the calculated results of the cleavage energies, relaxation energies, and surface energies of the investigated terminations, the charge compensation by the modification of the surface stoichiometry and the fillings of surface states were thermodynamically evaluated.