Research area:

Lattice Dynamics, phonons and other quasi-particle excitations in solids:

• Vibrational characteristics of crystals with complex defects;
• Dynamics of complex crystal lattices, strongly anisotropic crystal structures, and quasi-low-dimensional lattices.
• Quasi-particle spectra of nanosystems.

Main achievements:

• Microscopic calculations on the atomic dynamics of the real crystal structures (ideal and with defects) were made. New method for the localized states description based on J-matrix was suggested.
• Investigation of localization and propagation of vibrations in heterogeneous crystals and disordered solid solutions
• Creation of calculation models for investigation of electron and phonon spectra of graphene based structures.

Main Publications:

1. S. Feodosyev, I. Gospodarev, V. Grishaev, A. Kosevich, O. Kotlyar, E. Syrkin, Phonon Spectra and Discrete Oscillatory Levels in Crystal Superlattices of Deuterium- and Hydrogen-Palladium Solid Solutions, J. of Low Tem. Phys. 139, 665, 2005.
2. A.V. Kotlyar and S.B. Feodosyev, Local oscillations in crystal lattices with a simply connected region of the quasi-continuonsphonon spectrum, Low Temperature Physics, 32, No 3, 256, 2006.
3. I.A. Gospodarev, V.I. Grishaev, O.V. Kotlyar, K.V. Kravchenko, E.V. Manzhelii, E.S. Syrkin, and S.B. Feodosyev, Ioffe–Regel crossover and boson peaks in disordered solid solutions and similar peculiarities in heterogeneous crystal structures Low Temperature Physics, 34, No 8, 655, 2008.
4. A. Kosevich, I. Gospodarev, V. Grishaev, A. Kotlyar, V. Kruglov, E. Manzhelii, E. Syrkin, S. Feodosyev, Specific Features of the Transformation of Local Levels into an Impurity Band of Ag_1-pAl_p Disordered Solid Solutions, J. Exp. Theor. Phys. 105, 4, 2007
5. A Feher, E. Syrkin, I. Gospodarev, E. Manzhelii, A. Kotlyar, K. Kravchenko, The Features of Low Frequency Atomic Vibrations and Propaga-tion of Acoustic Waves in Heterogeneous Systems, in: “Waves in Fluids and Solids” (ed. R.P. Vila) “InTex” Open Access Publisher, ISBN 978-953-307-246-3 Croatia, 2011.
6. I. Gospodarev, O.V. Kotlyar, K.V Kravchenko, E.V. Manzhelii, E.S Syrkin, A.V.Yeremenko, I.K. Galetich, Low Temperature Peculiarities of Quasi-Particle Spectra of Disordered Solid Solutions, in: “Contemporary Problems of Mathematics, Mechanics and Computer Sciences” (eds. N.N. Kizilova, G.N. Zholtkevich) PRB Virovec’,ISBN 978-966-2579-92-5 Ukraine, 2011
7. A.Feher, I.Gospodarev, O.Kotlyar, K.Kravchenko, E.Manzhelii, E.Syrkin, S.Feodosyev Impurity levels in the electron spectra of graphene, Superlattices and Microstructures, 53, 55, 2013