The atomic and electronic structure of the TiO2- and BaO-terminated BaTiO3(0 0 1) surfaces in a paraelectric phase

Relaxation and rumpling of BaTiO3(0 0 1) surface with two different terminations have been investigated from ab initio local density approximation calculations. Large displacements of ions deviated from their crystalline sites have been obtained. These kinds of displacements lead to the formation the surface rumpling, dipole moments and electric field in the near-surface region. Band structures, density of states, bond population and electronic density redistributions have been obtained. Considerable enhancement of Ti–O chemical bond covalency nearby the surface, especially for the TiO2 termination surface, has been found.