First-principles characterization of the four phases of barium titanate

Using a first-principles approach, the four phases of perovskite barium tit anate are studied. We determine the lattice parameter, the bulk modulus and the cohesive energy of the cubic phase; the relaxed atomic positions in th e three ferroelectric structures; and the evolution of the electronic prope rties from one phase to the other. The role of electronic exchange-correlat ion energy in the stabilization of the different phases is also investigate d.