The method of secondary quantization in the strong bond approximation

© Kazan Federal University (KFU). Expressions for the calculation of the Fourier transform of the direct Coulomb interaction of electrons have been derived in the method of strong bond. It was shown that in the elaborated method it is not necessary to spread out nuclear charges over the crystal as it is done in the case of delocalized electrons

Long-range coulomb interaction of electrons of 4f orbitals in impurity centers Yb3+: KZnF3, CsCaF3, and Sm3+: CaF2

Expressions for calculating the matrix elements of the Coulomb interaction of f electrons of the isolated ion with an infinite crystal lattice have been obtained. The contribution of this interaction to the parameters of the crystal field in impurity centers Yb3+: KZnF3, CsCaF3, and Sm3+: CaF2 has been calculated. © 2013 Pleiades Publishing, Ltd

First-principles calculations of the amplitudes of the electron transition from a ligand to the 5d shell of Yb3+: KZnF3

The expressions describing the amplitudes of a transition of an electron from a ligand to vacant shells of the central ion of an impurity center are derived. The amplitudes of a transition of an electron from a ligand to the 5d shell of a rare-earth ion are calculated from first principles. The calculations are performed in the basis set of orbitals taken in the form of 5s, 5p, 4f, 5d, and 6s electron shells of the central ion and 2s and 2p electron shells of the ligands. No expansion in terms of overlap integrals is employed in the calculations. The matrix elements of the (I + S)-1 matrix are determined in the chosen basis set of orbitals. The amplitudes thus calculated are in good agreement with those obtained by fitting of the experimental data. © Nauka/Interperiodica 2006

Transferred hyperfine interactions for O17: LaMnO3

Parameters of the transferred hyperfine interactions (THFI) for O17: LaMnO3 have been estimated at room temperature. Satisfactory agreement with experiment has been obtained

Crystal field at the impurity center sites in ionic crystals

Perturbation theory is developed for second-quantized operators in a basis of partly nonorthogonal orbitals. This method may be helpful in carrying out ab initio calculations of the parameters of the crystal field at the impurity center sites. As an illustration, when estimating the crystal field parameters for Yb3+: KZnF3, some fitting parameters are calculated using this method. The results agree well with experimental data, which indicates that this theory shows considerable promise. © 2005 Pleiades Publishing, Inc

Long-range coulomb interaction in ionic crystals

Expressions have been proposed for calculating the matrix elements of the Coulomb interaction of p and d electrons in a chosen ion of a crystal with an infinite crystal lattice. The matrix elements have been calculated at Gaussian-type orbitals. The Coulomb interaction energy per molecular unit of the α'-NaV 2O 5 crystal has been calculated in the ionic approximation for homogeneous and chain orderings. It has been shown that the more correct determination of the energetic favorability of one or other ordering requires calculation of the Coulomb interaction energy with an infinite crystal lattice of electrons that are at different orbitals of the ion under consideration. © 2012 Pleiades Publishing, Ltd

Ligand hyperfine Yb3+ interaction in CsCaF3 and Cs2NaYF6 crystals

The operator, which determines the contribution of processes including the polarization of central ion core to the ligand hyperfine interaction (LHFI), has been obtained in the second quantization representation in the basis of partially nonorthogonal orbitals. The contributions of the impurity Yb3+ ion to the LHFI parameters have been also calculated in Cs2NaYF6 and CsCaF3 crystals, which are determined by the mechanisms studied earlier. The single-particle orbital basis has been extended as compared to the previous work. There is a sufficiently good agreement with the experiment. © 2011 Pleiades Publishing, Ltd

First-principles calculations of the hyperfine fields on ligands in fluorides

In solid-state physics, a crystal lattice is frequently approximated by an array of interacting ions. In this case, the wave functions of individual ions are assumed to be a fairly good zeroth approximation in calculating the matrix elements of the interaction Hamiltonian of electrons and nuclei of the lattice from first principles. Use of the second-quantization method is proposed for such calculations in the basis of these functions. As an example, the electron transition amplitude from a ligand to the central ion is estimated. The results agree well with the experimental data. © 2003 MAIK "Nauka/Interperiodica"

Genotoxicity of helicobacter pylori δpai in DNA comet assay

Chronic infection with Helicobacter pylori is a factor inducing development of cancer diseases. The mechanism of its action on the «host» DNA is still not clear. In present study we investigate genotoxical potential of two strains of H. pylori: wild type H. pylori P12 and PAI-deficienl mutant H. pylori δPAI. DNA damage was detected by DNA comet assay in gastric adenocarcinoma (AGS) and epithelial adenocarcinoma (HeLa) cells under neutral conditions using Tail Moment as a quantitative parameter. It was shown, that infection of AGS and HeLa cells with both strains H. pylori at different multiplicity of infection (20-500) for 6 h and infection of AGS for 12 h did not induce DNA damage. Our results revealed a significant dose-dependent increasing of Tail Moment in the AGS cells after infection with mutant H. pylori δPAI for 24 h, while genotoxity of wild type H. pylori P12 under the same conditions was not observed