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The first book to aid in the understanding of multiconfigurational quantum chemistry, Multiconfigurational Quantum Chemistry demystifies a subject that has historically been considered difficult to learn. Accessible to any reader with a background in quantum mechanics and quantum chemistry, the book contains illustrative examples showing how these methods can be used in various areas of chemistry,

The formalism underlying the calculations of local characteristics of the electronic structure of molecules and crystals by ab initio quantum-chemical methods was considered. Formulas for the bond order and the covalence and full valence of atoms in molecules and crystals were derived within the framework of the restricted and unrestricted Hartree-Fock methods. The correctness of the proposed appr

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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