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The formalism developed in molecular theory for calculation of local electronic-structure characteristics in a nonorthogonal atomic basis is generalized to systems with translational symmetry. Expressions have been derived to describe the bond orders, covalency, and valence in a crystal for restricted and unrestricted Hartree-Fock methods. Nonempirical electronic-structure calculations and an anal
A new scheme for calculating the electronic structure of crystals, based on the CNDO (complete neglect of differential overlap) approximation, is used to calculate the potential energy surfaces of diamond. Elastic properties such as the stiffness constants, the angular dependences of the anisotropy factor of Young's modulus, the Poisson ratios, and the Debye temperature are investigated on the bas
The chemical bonding in a series of nickel mixed oxides, namely Li2NiO2, Na2NiO2, tetragonal and orthorhombic La2NiO4 for Ni(II), LiNiO2, NaNiO2, LaNiO3 for Ni(III), BaNiO3 for Ni(IV) and LaNiO2, 'LaSrNiO3' for Ni(I), is investigated from the results of electronic structure calculations, including both band structure and local properties, i.e. atomic charges, covalent bond orders and atomic valenc
A new quantum chemical definition is proposed of the full atomic valence, VA, taking into account both the covalent and ionic parts of the chemical bonds formed by atoms in molecules and crystals. The full atomic valencies, covalencies, and charges on atoms are calculated for nickel–oxygen crystalline compounds in the CNDO band theory approximation. A comparison of the chemical bonding in nickel a
The electronic structure of eleven crystalline nickel oxides was investigated by band theory - CNDO method. Both the band and local properties of the electronic structure were calculated and were used for the description of chemical bonding in Ni(II) (NiO, Li2NiO2, Na2NiO2, K2NiO2, BaNiO2, La2NiO4), Ni(III) (LiNiO2, NaNiO2, LaNiO3) and Ni(IV) (BaNiO3) compounds.
The interactions between dissolved organic matter (DOM) and mineral particles are critical for the stabilization of soil organic matter (SOM) in terrestrial ecosystems. The processing of DOM by ectomycorrhizal fungi contributes to the formation of mineral-stabilized SOM by two contrasting pathways: the extracellular transformation of DOM (ex vivo pathway) and the secretion of mineral-surface-react
Modelling from quantum chemical data of the chemical bonding in NiO and La2NiO4 crystals comparatively to CuO and La2CuO4, is proposed. The increase of the ionicity degree of the Ni(II)–O bonding in comparison with Cu(II)‐O bonding is observed. The covalency is low and equally distributed in the equatorial plane and apical direction in the NiO6 octahedra in La2NiO4. As a supplementary data, which
The band structure and local properties of La2O3 and LaF3 crystals are investigated within the framework of CNDO approximation.
The crystalline structure of lead oxides is rewieved. In the framework of LUC‐CNDO computational scheme the electronic structure of PbO, PbO2, Pb2O3, and Pb3O4 crystals is investigated. The results obtained are compared with experimental data.
A quantum‐chemical definition is proposed of the full atomic valence taking into account both, covalent and ionic components of chemical bonds formed by an atom in molecules or crystals. Atomic charges, covalent bond orders, and full atomic valencies of lead and oxygen atoms in the crystalline lead oxides are calculated in the framework of the LUC‐CNDO approach.
A new quantum-chemical definition is given of the full atomic valence taking into account both the covalent and ionic parts of the chemical bonds formed by an atom in molecules and crystals. Full valence is close to formal ("classical") valence of an atom in a wide row of compounds. The theoretical consideration and the CNDO calculations of molecules and crystals are made to justify the validity o
LUC‐CNDO computation scheme and its valence theory applications are discussed. Electronic structure calculations of well‐known semiconductors Cu2O are reviewed. The parameters of CNDO scheme for copper–oxygen compounds are calibrated using the results of Cu2O band theory calculations and experimental data.
The crystalline structure of copper‐oxygen compounds with copper atom in the oxidation states I, II, and III is reviewed. A calculation is made of the electronic structure of the row of crystals with copper‐oxygen bonding. It is shown that the covalence effects are essential for copper oxide compounds containing copper atoms in oxydation states CuII and CuIII LUC‐CNDO calculations of La2CuO4 and Y
