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Information × Registration Number 0205U002003, 0102U000217 , R & D reports Title Investigation of the collective ionic and electron-ionic processes in solids on the basis of fermionic lattice models popup.stage_title Head Stasyuk Igor Vasyl'ovych, Registration Date 17-02-2005 Organization Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine popup.description2 Results of investigations of the energy spectrum, thermodynamic and dynamic properties of the electronic and ionic systems with strong short-range correlations of particles (Mott-Xubbard systems, systems with variable valence, extrinsic lattice systems, crystalls with hydrogen bonds) are presented. The general approach to examination of correlated hopping with the use of the dynamical mean-field theory is developed. A possibility of transition into a superconducting state is investigated for pseudospin-electron model with weak coupling at nonzero tunneling. The frequency dependence of the Raman scattering amplitude of light for pseudospin-electron model at different values of model parameters and at different relations between polarizations of initial and scattered light is investigated. Exact solutions for inelastic light scattering in strongly correlated materials are obtained with the use of the dynamical mean-field theory, Raman scattering cross-sections are calculated, and the valuable contribution of resonant effects into formation of scattering profiles and their temperature dependence is obtained. Considering proton transport in system with hydrogen bonds an energy spectrum of the one-dimensional proton conductor is investigated on the basis of the so-called orientational-tunnelling model taking into account short-range proton correlations in the reference-system approach and opportunity of the phase separation into areas with different proton concentrations is obtained. Applying such model to ionic subsystem in superionic conductor its dynamic properties are described: time correlation functions are found, frequency profiles of autocorrelation functions are analysed, the density of states of an ionic subsystem is calculated. The pseudospin-electron model is designed for the description of the correlated proton-electron transfer in the chain structures with hydrogen bonds. The thermodynamic properties of model are investigated. The frequency dependence of the real part of conductivity is obtained. Energies of various proton configurations are calculated. An intercalation of dipole particles in the layered crystalline medium is described within the generalized Blume-Еmery-Griffiths model. The phase diagrams are built. The phase diagrams and regions, where ferroelectric phase exist in Rochelle salt crystals, are built for the Mitsui model with transverse field in the mean field approximation. Theoretical investigations of dielectric properties of glycinium phosphite crystals affected by the transverse electric field were performed in the framework of both the order-disorder type model and the Landau expansion. The study predicts changes proportional to the second power of the field magnitude: decrease of the temperature of the paraelectric-ferroelectric phase transition and the jump of the transverse dielectric susceptibility in the phase transition point. An enhanced description of the thermodynamics of DMAGaS--DMAAlS ferroelectrics demonstrates that the account of Gaussian fluctuations leads to thecertain deformations of the phase diagram and decrease of the phase transition temperatures. An approach for the generalized description of kinetic processes taking into account widescale hydrodynamic fluctuations is developed for quantum Bose liquid. In such approach, the bounded set of equations for the quantum one-particle distribution function and hydrodynamic variable functional is obtained which will be utilized at examination of phase transitions from gaseous to fluid and superfluid states. The systems of interacting particles, taking into account forces of radiation reaction is investigated by methods of the relativistic theory of direct interactions. A series of quantum-mechanical models connected with quantum field theory is build and investigated. Conditions of Poincare-invariance of the variation description of the relativistic not dissipative continuum are formulated and solved. Keywords: strong correlation, correlated hopping, Raman scattering, metal-insulator transition, local anharmonicity, ionic conductor, hydrogen bonds, dynamical susceptibility, phase diagrams, quantum liquids, relativistic systems of particles, direct interactions. The report is written in Ukrainian in volume of 191 pages. The report consist of 5 parts and 2 Appendices and contains 72 figures, 2 tables, and 92 references to the publications executed on a theme. Product Description popup.authors popup.nrat_date 2020-04-02 Close