Archive

Department for High-Density Energy Physics

- The phenomenological model of confinement which treats the color string as a cylindrical bag with a surface tension is proposed. It provides with the relation between the surface tension of quark-gluon bags and color string tension and allows to determine the bag surface tension directly from lattice QCD calculations.
*K.A. Bugaev, G.M. Zinovjev* - New equation of state for a quark-gluon plasma is proposed. It obeys the specific qualitative features discovered in the lattice QCD calculations and gives the good agreement with the results of lattice SU(3) gluodynamics simulations.
*V.V. Begun, M.I. Gorenstein, O.A. Mogilevsky* - The model of non-femtoscopic correlations in proton-proton collisions is developed. This model absorbs the correlations induced by the conservation laws and also the correlations induced by the microjets. It successfully describes non-femtoscopic correlation functions of identical pions which have been received by analyzing the proton-proton collision data at the LHC energy 900 GeV.
*S.V. Akkelin, Yu.M. Sinyukov*

Department for Quantum Theory of Molecules and Crystals

- The evolution of averaged occupancies of molecular quasi-isoenergetic state in molecular systems where alternation of molecular energy levels is caused by discrete dichotomous and trichotomous stochastic fields, is studied. The dependence of the kinetics of transition processes on low and high frequency parameters of molecular levels fluctuation is characterized in detail. A novel physical mechanism for temperature-independent transitions in flexible molecular systems is proposed. This mechanism becomes effective when the conformation transitions between quasi-isoenergetic molecular states take place. At room temperatures, stochastic broadening of molecular energy levels predominates the energy of low-frequency vibrations accompanying transition. This leads to cancellation of the temperature dependence in the stochastically averaged rate constants. The proposed mechanism explains the temperature-independent onset of P2X3 receptor desensitization in neuronal membranes, as well as degradation of PER2 protein in embryonic fibroblasts.
*E.G. Petrov, V.I. Teslenko* - The concentrations of the injected by electric field charges across the 2D layers in fullerite-based FET are found. The relation between total amount of charge carriers and realistic electric field magnitude in FET structure is determined analytically. Maximal possible field-effect doping rate of fullerene molecules is estimated in break-down limit of gate dielectrics.
*O.L. Kapitanchuk*

Department for Quantum Electronics

- The possibility of an arbitrary number of vortex-antivortex pairs generation in vortex-state magnetic nanodisk is demonstrated. The mentioned generation occurs under influence of the external magnetic field of the certain space and time configuration. Scheme of an experimental setup for observation of the mentioned phenomena is proposed. The theoretical model is build, the model is based on the nonlinear resonance in system of certain magnon modes. Theoretical results are verified using micromagnetic modeling.
*Yu. Gaididei, V.P. Kravchuk, D. D. Sheka*

Department for Mathematical Methods in Theoretical Physics

- The quasi-bosons were considered which are composite bosons (like mesons, excitons etc.). They are composed by two fermions with creation and annihilation operators satisfying non-standard commutation relations. The conditions are clarified which allow to realize the quasi-boson operators by the operators of deformed (nonlinear) oscillator. It is proved that such deformed oscillator exists and it is unique in the family of deformations under consideration.
*A.M. Gavrilik, Yu.A. Mischenko* - For the superintegrable ZN-symmetric chiral Potts quantum chain of finite length, on the base of the notion of Onsager sectors (the spaces of irreducible representations of Onsager algebra), the spin matrix elements between eigenstates of Hamiltonian of quantum chain were found in a factorized form up to a common scalar factor, known for the Onsager sectors with the lowest energies. For the quantum Ising chain in a transverse field (the case of N=2) the uknown scalar factors were found for all the Onsager sectors by the method of fermion operators. For general N, the matrix elements between vacuum states in the thermodynamic limit were obtained and the formula for the order parameters was derived.
*N.Z. Iorgov, V.N. Shadura, Yu.V. Tykhyy*

Department for Theory of Nonlinear Processes in Condensed Matter

- Superconducting properties of the two-dimensional model of a metal with a spectrum that contains an insulating gap which can lay either below or above Fermi level has been studied. It has been shown that presence of this gap influences the superconducting gap as well as the critical temperatures T
_{c }and T_{c}^{MF}. In particular, jumps of the derivatives of these temperatures have been identified as functions of doping or Fermi level position.*V.M. Loktev* - The experimental data on the influence of the spin-polarized current on the dynamics of the magnetization vector of an antiferromagnetic layer have been analyzed. A precessional regime of motion of this vector with the linear dependence of its frequency on the current has been found. The intensity of the pulses that excite such precession and the influence of the external magnetic field has been estimated. The results appear to be in accordance with the available observation.
*V.M. Loktev* - A possibility of binding of two excess electrons in a solitonic state in anharmonic molecular lattices with electron-phonon interaction has been proven. The energy, mass and the localization length of such bisolitonic states has been calculated.
*L.S. Brizhik* - Dynamics of large charged polarons in one-dimensional diatomic lattices under the influence of an external periodic electromagnetic field with zero mean has been investigated. The possibility of rectification of polaron motion if the field intensity and its period exceed certain critical value has been demonstrated.
*L.S. Brizhik, A. A. Eremko* - The role of the interlayer exchange interactions in the formation of magnetic structures with different packing sequences of the dense-packed molecular planes in the δ-phase of solid oxygen has been investigated. It has been shown that the temperature- or pressure-induced variation in the intermolecular distances gives rise to the change of the exchange coupling between the nearest close-packed planes and, as a result, causes transitions between different magnetic phases of δ-oxygen. The interpretation of the recently experimentally measured phase diagram of δ-oxygen has been done on the basis of the proposed model.
*H.V. Gomonay* - A theory of optoacoustic phenomena for metallic nanoclusters incorporated in a insulating matrix that has been developed. It makes possible to determine the amplitude of the sound oscillations of the matrix when the clusters are excited by a laser. In the field of plasmonic resonances a considerable difference between the optoacoustic properties of discrete and continuous metal films on the surface of the transparent insulating matrix has been obtained.
*N.N. Grigorchuk* - The investigation of the regularity of the electric field penetration into the structured system of electrolytes, in particular into a biological structure. The equations that describe such a process have been obtained and the characteristics of the electric fields that can effectively penetrate into the living objects. The obtained results have been used during the experimental investigation of the electric field influence on the bacteria. In particular, a sharp hydrophobicity rise (sevenfold) in such objects after the action of weak electric field has been detected experimentally.
*V.N. Ermakov* - The scattering processes on the point-dipole one-dimensional potentials that can be defined as a weak limit of the regular finitely separated well- and barrier–shaped functions. It has been shown that resonant tunneling across the point potentials depends on the regularization of these potentials.
*A.V. Zolotaryuk* - Directed motion of domain walls (DWs) in a classical biaxial ferromagnet placed under the influence of periodic unbiased external magnetic fields has been obtained. The symmetry approach for the analysis of the equations of motion has been developed and the necessary conditions for the directed DW motion have been found. With the help of the soliton perturbation theory and numerical simulations, the average DW velocity as a function of different system parameters such as damping constant, amplitude, and frequency of the external field, is computed.
*Y. Zolotaryuk* - Longitudinal magnetic susceptibility of a two-dimensional quantum Ising model in a transversal magnetic field in the wide temperature range and near the quantum critical point has been investigated. The asymptotic scaling behavior of the longitudinal magnetic susceptibility has been obtained.
*O.B. Kashuba* - The average first passage time during which the intensity of the electron flow across the tunneling system rises from the initially low value to the value that guarantees transition to the new stationary state has been computed with the help of numerical simulations. This time has been obtained for the different noise parameters: its intensity and the correlation time. Numerical simulations have shown that the process slows down in the sense that the relaxation time increases monotonically as a function of the correlation time, while at the same time the rise of the noise intensity accelerates the transition.
*O.O. Ponezha* - The model with optical phonons that can describe the phonon spectrum of graphene with sufficiently high precision. It has been shown how the electron-phonon interaction renormalizes the electron motion on the Fermi surface due to the presence of the effective mass renormalization parameter. In the case of graphene this parameter depends on the chemical potential has the physical meaning of the velocity renormalization. It has been shown that the chemical potential value is shifted with respect to its value in the free zone. The relative position of the Dirac point is also being renormalized respectively.
*S.G. Sharapov*

Department for Computational Methods in Theoretical Physics

- The present work investigates the relationship between the stability of multi-electron systems and the protonation. The intricacy of the protonation sites and the protonated states that are absorbed into the concept of the proton affinity is discussed, particularly addressing its range of validity. This work can also be considered as an attempt to have a look “at different angles” at one of the most important molecular processes that occur in nature and that are reflected in our mirror of the perception of nature.
*V.Ya. Antonchenko, E.S. Kryachko* - Тheoretical studies the thermoelectricity properties of organic molecules. Explained the mechanism of the thermoelectricity of such molecules which associated with tunneling of electrons through HOMO and LUMO levels these molecules. Investigated of the two dimensional hybrid nanostructures ferromagnetic -superconductors. Spin-orientation phase transition to study in these systems depending on temperature. We investigate the band structure of Fe-based using the first-principle method of density-functional theory .It was shown that there is scope for rising of Tc for this superconductors.
*S.P. Kruchinin* - It is shown that the structural response of the protein macromolecule performing a biochemical reaction manifests itself through the gamma-distribution of relaxation times which is of universal character and holds at all temperatures of the protein functioning.
*L.N. Christophorov* - Five 20-nanogold low-energy hollow cages are identified at the density functional level by performing a computational search on the corresponding potential energy surfaces in the different charge states. Their structures and stabilities are investigated and compared with the tetrahedral ground-state and space-filled cluster Au20(Td). Special attention is devoted to the bifunctional reactivity of the studied Au20 hollow cages: the outer, exo-reactivity and the inner, void reactivity. The latter results in endohedrality, i. e. in the existence of @-fullerenes of gold. We analyze the general features of the voids of the reported 20-nanogold fullerenes. The void reactivity of these 20-nanogold hollow cages is the key theme - it is suggested that, together with the global characteristics, such as the ionization potential and electron affinity, the molecular electrostatic potential and HOMO-LUMO patterns are actually tools that may shed a light on the general features of voids of these golden fullerenes and their capability to encage H and Li. The confinement character of the studied golden fullerenes is compared with the classical examples, C60 in particular. For the first time it is demonstrated the very existence of the stable endo-20-nanogold fullerene Li@Au20.
*E.S. Kryachko* - The properties of water solution 2D model system in NPT-ensemble were studied in the frames of Monte Carlo method. Dependencies of thermodynamic properties on the impurity particle size and concentration were considered. Strengthening of hydrogen bonds takes place in the vicinity of small-size impurity particles. When the particles grow in size, the structure of hydrogen bonds becomes more loosen and the particles are likely to form aggregates. Phase transition temperature under constant pressure exhibits a tendency to decrease. Obtained results and developed computational procedure can be used in the experimental data analysis on the inert gas solutions in water systems.
*N.V. Gloskovskaya*

Department for Applied Problems in Theoretical Physics

- For quantum systems of particles with an interaction in the form of a superposition of smooth and delta-type potentials in two- and three-dimensional spaces, it is proved with complete account of pair correlations that the attractive delta-potentials cause the collapse of a system, whereas the repulsive delta-potentials give no contribution into all spectral characteristics of the system. Thus, the delta-potentials are shown to be efficient only for one-dimensional systems.
*I.V. Simenog, B.E. Grinyuk, M.V. Kuzmenko* - Halo-nuclei
^{6}Не and^{6}Li are studied within a model of α-particle plus two extra nucleons, and nuclei^{10}Bе and^{10}С are explored within a four-cluster model with two α-particles and two extra nucleons. New versions of the αα-interaction involving local and non-local potentials are proposed. The density distributions, pair correlation functions, and form factors are calculated. The dependence of the form factors on the momentum transferred is explained.*B.E. Grinyuk, I.V. Simenog* - The asymptotics of the density distributions and the pair correlation functions of
^{3}H and^{3}He nuclei are obtained. The experimental momentum distributions of nucleons and the charge form factors are explained.*D.V. Piatnytskyi, I.V. Simenog* - The energy dependence of the Woods--Saxon-type interaction potential for the
^{13}С +^{16}О scattering is studied with regard for the bulk and surface absorptions. It is found that the potential is of quasimolecular form.*I.V. Simenog* - The density distributions of particles, mass and charge form factors, and two-particle correlation functions are calculated and analyzed for a number of reference atomic and molecular three-particle systems. The asymptotic behavior of the density distributions and the form factors are studied. The form factors of three-particle systems are shown to decrease according to a power law universal for all the Coulomb systems.
*M.V. Kuzmenko, I.V. Simenog* - Possibilities of the determination of a symmetry of energy states obtained by means of stochastic variational calculations without preliminary symmetrization of the states are studied for the systems of three and four charged particles. Some local and integral computational schemes are proposed to determine a posteriori the permutational symmetry of bound states.
*I.V. Simenog, M.V. Kuzmenko, V.M. Khryapa*

Department for Theory and Simulation of Plasma Processes

- The microscopic phase density and its generalizations are considered. The procedure of derivation of hydrodynamic-type nonlinear equations for average values is generalized. We show that the last can be obtained based on equivalent description of evolution process. We investigate a solution of Cauchy problem of equations for average values of general case observable. The solution is represented with respect to the arity index of observable, evolution of which is presented by the certain evolution operators. We analyze the generalized hydrodynamic-type evolution equation for one particle distribution function.
*V. Shtyk*

Department for Theory of Nuclei and Quantum Field Theory

- We have studied polarization of the vacuum of a quantized scalar field which is subject to the Dirichlet condition at the boundary of an impenetrable magnetic vortex. It is shown that the vacuum energy is induced in the case when the Compton wavelength associated with the scalar field exceeds considerably the vortex thickness; the amount of the vacuum energy depends periodically on the vortex flux.
*Yu.A. Sitenko* - Total cross section of neutron-proton scattering at zero energy σ
_{0}was calculated using the data on total cross sections in the energy region 0-150 keV. The obtained value of the cross section is in very good agreement with the experimental cross sections of Houk and Hurst, but contradicts to the experimental cross section of Dilg.*V.A. Babenko, N.M. Petrov*