LCAO Calculations of Perfect-Crystal Properties

Abstract

In this chapter perfect-crystal properties are considered: the analysis of chemical bonding on the basis of the population analysis; the one-electron properties and properties, defined by the total energy and its derivatives; and the magnetic ordering in crystals. We demonstrate that the use of hybrid exchange-correlation functional allows reproducing the equilibrium volumes and structural, electronic, dielectric, and vibrational properties of paraelectric cubic and three ferroelectric (tetragonal, rhombohedral, and orthorhombic) BaTiO3 phases in good agreement with the existing experimental data. It is also shown that the use of the first-principles LCAO approach allows BaTiO3 thermodynamic properties calculation, providing valuable information on the low-temperature behavior that is not easy to obtain by experimental techniques. The efficiency of the LCAO method in the quantum mechanics–molecular dynamics approach to the interpretation of X-ray absorption is illustrated using perovskite and ReO3 examples.