Bulletin of the Karaganda University Physics Series

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An overview of light ray deflection calculation by magnetars in nonlinear electrodynamics
(2024-06-24)
Nurzada Beissen
;
Medeu Abishev
;
Saken Toktarbay
;
Tursynbek Yernazarov
;
Manas Khassanov
Due to the lack of experimental confirmation of the effects of nonlinear electrodynamics (NED) of vacuum on the electromagnetic wave, it remains the most pressing issue. One of the most optimal media for studying these effects, occurring in astrophysics, are magnetars. Various methods of studying the bending of a wave passing through the magnetospheres of magnetars play a key role in a deeper understanding of vacuum NED. This article reviews modern methods for determining the angle of bending of the electromagnetic wave under the effect of NED of vacuum and gravity, with special attention paid to NED of vacuum in intense electromagnetic fields, which is a characteristic feature of magnetars. The article discusses various methods and techniques used to measure these angles, as well as their potential astrophysical applications.
Цитирования (OpenAlex) 2
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Theoretical study of the Ni–C system in the pressure range of 0–100 GPa
(2021-12-30)
Aisulu U. Abuova
;
Талгат Муратович Инербаев
;
Fatima U. Abuova
;
G. A. Kaptagay
This work is devoted to the search for stable compounds and structures in the Ni–C system in the pressure range of 0–100 GPa. Based on the density functional theory, a search for stable compounds and structures in the Ni–C system was carried out using modern algorithms for predicting crystal structures. As a result, one stable intermediate compound Ni3C with the structure of cementite, previously synthesized at 184 GPa, was revealed. Ni3C nickel carbide is dynamically stable, which is confirmed by the absence of imaginary modes in the phonon spectra. According to the results obtained, Ni3C is formed by the reaction of 3Ni + C ↔ Ni3Cabove 23 GPa and is stable up to at least 100 GPa. Spin-polarized calculations showed that the Ni3C has no magnetic moment in the entire pressure range. For carbon-rich compounds, performed calculations on the crystal structure prediction did not reveal any phase that would be energetically favorable relative to amixture of pure nickel and carbon. Also, it was shown that the most energetically favorable modification of metastable carbide Ni7C3 is orthorhombic Ni7C3-Pbca.
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DFT studies of BaTiO3
(2023-06-30)
Талгат Муратович Инербаев
;
Zh. Ye. Zakiyeva
;
Fatima U. Abuova
;
Aisulu U. Abuova
;
S. A. Nurkenov
The structure of stable phases is investigated using first-principle calculations based on the functionals: LDA, GGA and newly developed general-purpose heavily constrained and appropriately normalized meta GGAfunctional (SCAN). The purpose of this study is to theoretically study the atomic displacements and band gap of the cubic, tetragonal, orthorhombic, rhombohedral perovskite phases for the comparison LDA, GGA-PBE and meta-GGA functionals using the density functional theory method. The obtained data of the density of states (DOS) showed that the values of the band gap energies are underestimated, and the DOS values show that the upper part (valence band) mainly consists of O 2p orbitals, the lower part (conduction band) consists of Ti 3d orbitals. The rhombohedral phase has a mixed composition of Ti states in the conduction band with a greater degree of 3dz2 than 3dxy. The values of the energies of the band gap (Egap) and the density of states show reasonable agreement with experimental and theoretical data. The LDA functional and, to a lesser extent, the GGA - PBE functional can also provide fairly accurate information about atomic displacements in these crystals. The values calculated by the SCAN functional do not differ much from the GGA and LDA functionals.
Цитирования (OpenAlex) 4Цитирования (OpenCitations) 3

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