First-principles study on the (0Â 0Â 1) surface of cubic PbZrO3 and PbTiO3

We present first-principles calculations on the (0 0 1) surface of cubic PbZrO3 and PbTiO3 with the PbO and B (Ti or Zr) O2 terminations. For the BO2 terminated surface, the largest relaxations are on the second layer atoms and not on the first layer ones. This behavior is very different to SrTiO3 and BaTiO3. The analysis of the structure relaxation parameters reveals that the rumpling of the (0 0 1) surface for PbZrO3 with the PbO termination is stronger than that of PbTiO3. For the PbO-terminated surface of PbZrO3, the surface state appears at the X point of its band structure. The result of the charge density shows the Pb-O covalent interaction in the surface is stronger than that of the bulk system for both the types of the surface of both the materials.