AB-INITIO CALCULATIONS OF THE ELECTRONIC-STRUCTURE AND OPTICAL-PROPERTIES OF FERROELECTRIC TETRAGONAL BATIO3

The electronic structure, charge distribution, effective charge, and c harge transfer in ferroelectric tetragonal BaTiO3 are carefully studie d using a local density functional potential and a self-consistent ab initio LCAO (linear combination of atomic orbitals) method. It is show n that the band gap and low-energy conduction band can be calculated w ith a reasonable accuracy when the ab initio LCAO method is used with an optimum basis set of atomic orbitals. The calculated optical spectr um, band gap, and effective mass of BaTiO3, obtained from the calculat ed electronic structure, are in good agreement with experimental resul ts.