Browsing by Subject "Ab-initio calculations"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Electronic properties of spin excitation in multiferroics with a spinel structure: first principles calculation
    (Taylor & Francis, 2019-06-04) Koç, H.; Palaz, S.; Mamedov, Amirullah M.; Özbay, Ekmel
    In the present work, the structural, electronic and mechanical properties of LiVCuO4 and LiCu2O4 spinel type multiferroics have been investigated by means of first principles calculations. The spin polarized generalized gradient approximation has been used for modeling exchange-correlation effects. The structural optimization of these multiferroics compounds has been performed by using VASP-code, and the lattice parameters and magnetic moments have been calculated. From our calculation, it has been determined that the LiVCuO4 compound is a narrow band gap semiconductor, while the LiCu2O4 compound is metallic in nature. Considering the spin states from the electronic band structure and density of the state (DOS) of the LiVCuO4 compound, it has been identified that Eg=1.87 eV for spin up and Eg=0.37 eV for spin down. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work.
  • Thumbnail Image
    ItemOpen Access
    Slater insulator phase of X2 (X = Na, Li)IrO3: first principles calculation
    (Taylor & Francis, 2021-12-01) Koc, H.; Palaz, S.; Mamedov, Amirullah M.; Ozbay, Ekmel
    In the present work, the structural, electronic and mechanical properties of Na2IrO3 and Li2IrO3 have been investigated by means of first principles calculations. The spin polarized generalized gradient approximation has been used for modeling exchange-correlation effects. The structural optimization of these compounds has been performed by using VASP-code, and the lattice parameters and magnetic moments have been calculated. From our calculation, it has been determined that X2IrO3 (X = Na, Li) compounds for both spin up and spin down states are indirect wide gap semiconductor in nature. Considering the spin states from the electronic band structure and density of the state (DOS) of the Na (Li)2IrO3 compounds, it has been identified that Eg=1.824 (2.315) eV for spin up and Eg=1.558 (2.019) eV for spin down. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work.
  • Thumbnail Image
    ItemOpen Access
    Strain effects and electronic structures of narrow band P-R ferroelectrics: first principles calculation
    (Taylor & Francis, 2019) Bozdağ, N.; Koç, H.; Şimşek, Ş.; Mamedov, Amirullah M.; Özbay, Ekmel
    In the present work, the structural, mechanical, electronic and optical properties of the Ruddlesden–Popper(RP) Ba3X2S7 (X = Zr, Hf, Ti) sulfides compounds have been investigated by means of first principles calculations. The generalized gradiend approximation has been used for modeling exchange-correlation effects. It has been observed that the calculated lattice parameters are in good agreement with the experimental values. Bulk modulus, shear modulus, Young’s modulus Poisson’s ratio, and Poisson’s ratio from the calculated elastic constants for Ba3Zr2S7, Ba3Hf2S7, and Ba3Ti2S7 compounds, respectively have been obtained. The obtained electronic band structure for Ba3Zr2S7 and Ba3Hf2S7 compounds are semiconductor in nature, and the Ba3Ti2S7 compound also is metallic. Based on the obtained electronic structures, we further calculated the frequency-dependent dielectric function and other optical functions along the x- and z- axes.