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Your search keyword '"Zhumagulov, Ya. V."' showing total 15 results
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15 results on '"Zhumagulov, Ya. V."'

1. Excitonic effects in time-dependent density functional theory from zeros of the density response

Author

Gulevich, D. R., Zhumagulov, Ya. V., Kozin, V., and Tokatly, I. V.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We show that the analytic structure of the dynamical xc kernels of semiconductors and insulators can be sensed in terms of its poles which mark physically relevant frequencies of the system where the counter-phase motion of discrete collective excitations occurs: if excited, the collective modes counterbalance each other, making the system to exhibit none at all or extremely weak density response. This property can be employed to construct simple and practically relevant approximations of the dynamical xc kernel for time-dependent density functional theory (TDDFT). Such kernels have simple analytic structure, are able to reproduce dominant excitonic features of the absorption spectra of monolayer semiconductors and bulk solids, and promise high potential for future uses in efficient real-time calculations with TDDFT., Comment: 10 pages, 4 figures

Published
2022
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6. Исследование магнитных, нематических и сверхпроводящих свойств высокотемпературных сверхпроводников на основе железа методом вариационного кластерного приближения

Author

Лукьянов, A. Е., Zhumagulov, Ya. V., Neverov, V. D., Lukyanov, A. E., and Krasavin, A. V.

Subjects
Condensed Matter::Superconductivity
Abstract

A class of high-temperature superconductors (HTSC) based on iron was discovered in 2008 [1]. Although more than nine years have elapsed since the discovery, an unambiguous microscopic theory explaining the complex phase diagrams of this class of superconductors has not yet been created [2]. This work is aimed at restoring the phase diagram of iron-based HTSC at zero temperature by variational cluster approximation [3].

Published
2018

7. PYED + VCA: EXACT DIAGONALIZATION OF FINITE QUANTUM SYSTEMS WITH VARIATIONAL CLUSTER APPROXIMATION

Author

Лукьянов, A. Е., Lukyanov, A. E., Neverov, V. D., Zhumagulov, Ya. V., and Krasavin, A. V.

Abstract

The method of exact diagonalization is one of the main methods in studying the properties of strongly correlated systems. Together with the variational cluster approximation [1], this method makes it possible to study a fairly wide range of different systems. In this paper we present an open source implementation [2] of exact diagonalization and variational cluster approximation.

Published
2018

13. Effect of Optical Excitation on the Band Structure and X-Ray Absorption Spectra of BaBiO3-Based High-Temperature Superconductors: Ab Initio Calculation.

Author

Zhumagulov, Ya. V., Krasavin, A. V., Lukyanov, A. E., Neverov, V. D., Yaroslavtsev, A. A., and Menushenkov, A. P.

Subjects
*X-ray absorption spectra, *SUPERCONDUCTORS, *FREE electron lasers, *DENSITY functionals, *EXCITED states, *FERMI level, *X-ray absorption
Abstract

The band structure, densities of states, and O K-edge X-ray absorption spectra have been calculated by the density functional theory method for BaBiO3-based perovskite high-temperature superconductors at different potassium doping levels in the ground and optically excited states. It has been shown that this approach including local structural inhomogeneities caused by doping and optical irradiation allows the correct description of changes in the properties of the electron subsystem near the Fermi level. It has been shown that doping is accompanied by the appearance of hole carriers on the Bi6s−O2pσ*. hybridized orbital in agreement with the model of the electronic structure of bismuth-based high-temperature superconductors in terms of a spatially separated Fermi-Bose mixture. It has been found that the band structure for the excited state of the undoped compound is equivalent to the band structure of the tight binding model for a cubic lattice. The results are important for the preliminary analysis of time-resolved X-ray absorption spectra on an X-ray free electron laser at femtosecond optical excitation. [ABSTRACT FROM AUTHOR]

Published
2019
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