TY - JOUR

T1 - Full Inclusion of Symmetry in Constructing Wannier Functions

T2 - Chemical Bonding in MgO and TiO2 Crystals

AU - Évarestov, R. A.

AU - Usvyat, D. E.

AU - Smirnov, V. P.

N1 - Funding Information: ACKNOWLEDGMENTS This study was supported by the Russian Foundation for Basic Research, project nos. 02-03-32738 and 03-03-06124.

PY - 2003/11

Y1 - 2003/11

N2 - Chemical bonding in MgO and TiO2 crystals is analyzed using a minimal basis consisting of atomic-type Wannier functions (AWFs) centered at atomic sites in the crystal and constructed from Bloch states of the energy bands originating from the valence states of the atoms. A method proposed earlier for constructing Wannier functions is improved. Symmetrization of the initial Bloch function basis and symmetrical orthogonalization of the generalized Bloch functions greatly reduces computational effort. The prior symmetrization of the Bloch function basis is of fundamental importance in constructing AWFs, because the latter functions have to be centered at the atomic sites and possess the symmetry of the atomic functions in the crystal. The principle that should be followed in selecting the conduction bands originating from the valence states of the atoms of the crystal is formulated. The Bloch functions are calculated using the LCAO approximation within the Hartree-Fock method and density-functional theory. Using the calculated Bloch functions, a minimal valence AWF basis is constructed and calculations of the local characteristics of the electronic structure (atomic charge, bond order, atomic valence) are performed for the MgO and TiO2 crystals. According to the analysis performed, the covalent component of the chemical bonding in the MgO crystal is negligibly small and TiO2 is a mixed ionic and covalent crystal with pronounced covalent bonding.

AB - Chemical bonding in MgO and TiO2 crystals is analyzed using a minimal basis consisting of atomic-type Wannier functions (AWFs) centered at atomic sites in the crystal and constructed from Bloch states of the energy bands originating from the valence states of the atoms. A method proposed earlier for constructing Wannier functions is improved. Symmetrization of the initial Bloch function basis and symmetrical orthogonalization of the generalized Bloch functions greatly reduces computational effort. The prior symmetrization of the Bloch function basis is of fundamental importance in constructing AWFs, because the latter functions have to be centered at the atomic sites and possess the symmetry of the atomic functions in the crystal. The principle that should be followed in selecting the conduction bands originating from the valence states of the atoms of the crystal is formulated. The Bloch functions are calculated using the LCAO approximation within the Hartree-Fock method and density-functional theory. Using the calculated Bloch functions, a minimal valence AWF basis is constructed and calculations of the local characteristics of the electronic structure (atomic charge, bond order, atomic valence) are performed for the MgO and TiO2 crystals. According to the analysis performed, the covalent component of the chemical bonding in the MgO crystal is negligibly small and TiO2 is a mixed ionic and covalent crystal with pronounced covalent bonding.

UR - http://www.scopus.com/inward/record.url?scp=0345149540&partnerID=8YFLogxK

U2 - 10.1134/1.1626740

DO - 10.1134/1.1626740

M3 - Article

AN - SCOPUS:0345149540

VL - 45

SP - 2072

EP - 2082

JO - Physics of the Solid State

JF - Physics of the Solid State

SN - 1063-7834

IS - 11

ER -