NASU Bogolyubov Institute for Theoretical Physics

Kiev, Ukraine

NASU Bogolyubov Institute for Theoretical Physics

Kiev, Ukraine
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Zelinskyy Y.,Humboldt University of Berlin | Zelinskyy Y.,NASU Bogolyubov Institute for Theoretical Physics | May V.,Humboldt University of Berlin
Nano Letters | Year: 2012

The photoinduced switch of the current through a single molecule is studied theoretically by including plasmon excitations of the leads. A molecule weakly linked to two spherical nanoelectrodes is considered resulting in sequential charge transmission scheme. Taking the molecular charging energy (relative to the equilibrium lead chemical potential) to be comparable to the molecular excitation energy, an efficient current switch in a low voltage range becomes possible. A remarkable enhancement of the current is achieved due to simultaneous plasmon excitations in the electrodes. The behavior is explained by an increased molecular absorbance due to oscillator strength transfer from the electrode plasmon excitations and by a net excitation energy motion from the electrodes to the molecule. © 2011 American Chemical Society.

Iakubovskyi D.,NASU Bogolyubov Institute for Theoretical Physics
Monthly Notices of the Royal Astronomical Society: Letters | Year: 2015

It is currently unclear whether the new line at ~3.5 keV, recently detected in various samples of galaxy clusters, the Andromeda galaxy and the central part of our Galaxy, is caused by potassium emission lines. By using the latest astrophysical atomic emission line data base, AtomDB v. 3.0.2, we show that the most promising method to check its potassium origin directly will be the study of the K XIX emission line complex at ~3.7 keV using forthcoming X-ray imaging spectrometers such as the Soft X-ray spectometer onboard the Astro-H mission or the microcalorimeter onboard the Micro-X sounding rocket experiment. In order to further reduce the remaining (factor of ~3-5) uncertainty of the 3.7/3.5 keV ratio, more precise modelling should be performed, including the removal of significant spatial inhomogeneities, a detailed treatment of background components, and the extension of the modelled energy range.

Martynov E.,NASU Bogolyubov Institute for Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The model of elastic scattering amplitudes dominated by the triple (at t=0) Pomeron pole suggested earlier is modified to confront to existing experimental data on pp and p̄p total and differential cross sections at √s≥19 GeV and |t|≤14.2 GeV2 including the newest TOTEM data. Predictions for the future TOTEM measurements at 13 and 14 TeV are given. © 2013 American Physical Society.

Gorenstein M.I.,NASU Bogolyubov Institute for Theoretical Physics
Physical Review C - Nuclear Physics | Year: 2011

An incomplete particle identification distorts the observed event-by-event fluctuations of the hadron chemical composition in nucleus-nucleus collisions. A new experimental technique called the identity method was recently proposed. It eliminated the misidentification problem for one specific combination of the second moments in a system of two hadron species. In the present paper, this method is extended to calculate all the second moments in a system with an arbitrary number of hadron species. Special linear combinations of the second moments are introduced. These combinations are presented in terms of single-particle variables and can be found experimentally from the event-by-event averaging. The mathematical problem is then reduced to solving a system of linear equations. The effect of incomplete particle identification is fully eliminated from the final results. © 2011 American Physical Society.

Zolotaryuk A.V.,NASU Bogolyubov Institute for Theoretical Physics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

Two rectangular models described by the one-dimensional Schrödinger equation with sharply localized potentials are suggested. The potentials have a multilayer thin structure being composed from adjacent barriers and wells. Their peculiar tunneling properties are studied in considerable detail. Particularly, in the zero-range limit when the potentials are squeezed to a single point, sharp peaks with total transmission are observed at certain (positive and negative) quantized values of the potential strength constant forming infinite discrete sets. Beyond these sets, the barrier-well structures behave as a perfectly reflecting wall. The transcendental equations with respect to potential strengths, the solutions of which determine transmission (resonance) sets, are derived. In this regard, both the models are exactly solvable. The energy dependence of an incident particle is shown to reveal a resonance behavior, being completely different from that observed in a typical double-barrier structure. © 2013 American Physical Society.

Gavrylenko P.,NASU Bogolyubov Institute for Theoretical Physics
Journal of High Energy Physics | Year: 2015

Abstract: We study the solution of the Schlesinger system for the 4-point slN isomonodromy problem and conjecture an expression for the isomonodromic τ-function in terms of 2d conformal field theory beyond the known N = 2 Painlevé VI case. We show that this relation can be used as an alternative definition of conformal blocks for the WN algebra and argue that the infinite number of arbitrary constants arising in the algebraic construction of WN conformal block can be expressed in terms of only a finite set of parameters of the monodromy data of rank N Fuchsian system with three regular singular points. We check this definition explicitly for the known conformal blocks of the W3 algebra and demonstrate its consistency with the conjectured form of the structure constants. © 2015, The Author(s).

Gamayun O.V.,NASU Bogolyubov Institute for Theoretical Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We calculate one-loop polarization in bilayer graphene in the four-band approximation for arbitrary values of frequency, momentum, and doping. At low and high energy our results reduce to the polarization functions calculated in the two-band approximation and in the case of single-layer graphene, respectively. The special cases of static screening and plasmon modes are analyzed. © 2011 American Physical Society.

Tomchenko M.D.,NASU Bogolyubov Institute for Theoretical Physics
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

An approximate microscopic model is proposed to explain the electric signal U k BT/2e observed by A. S. Rybalko [Fiz. Nizk. Temp. 30, 1321 (2004)] in He II in experiments with standing half-waves of second sound. The model is based on the idea, due to Gutlyanskii, of one-directional polarization of He4 atoms located at the electrode surface. The calculated parameters of the electric signal are in approximate agreement with the experimental ones. It is also predicted that a standing half-wave of first sound should induce a variable signal with amplitude U-p/en~3×10 -5pV/atm at the electrode. © 2011 American Physical Society.

Zolotaryuk A.V.,NASU Bogolyubov Institute for Theoretical Physics
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

The one-dimensional Schrödinger equation with the point potential in the form of the derivative of Dirac's delta function, λ δ′ (x) with λ being a coupling constant, is investigated. This equation is known to require an extension to the space of wave functions ψ (x) discontinuous at the origin under the two-sided (at x = ± 0) boundary conditions given through the transfer matrix ((A, 0; 0, A- 1)) where A = frac(2 + λ, 2 - λ). However, the recent studies, where a resonant non-zero transmission across this potential has been established to occur on discrete sets {λn}n = 1 ∞ in the λ-space, contradict to these boundary conditions used widely by many authors. The present communication aims at solving this discrepancy using a more general form of boundary conditions. © 2010 Elsevier B.V. All rights reserved.

Grigorchuk N.I.,NASU Bogolyubov Institute for Theoretical Physics
Journal of the Optical Society of America B: Optical Physics | Year: 2012

The local field approach and kinetic equation method is applied to calculate the surface plasmon radiative damping in a spheroidal metal nanoparticle embedded in any dielectric media. The radiative damping of the surface plasmon resonance as a function of the particle radius, shape, dielectric constant of the surrounding medium, and the light frequency is studied in detail. It is found that the radiative damping grows quadratically with the particle radius and oscillates with altering both the particle size and the dielectric constant of a surrounding medium. Much attention is paid to the electron surface-scattering contribution to the plasmon decay. All calculations of the radiative damping are illustrated by examples on the Au and Na nanoparticles. © 2012 Optical Society of America.

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