Browsing by Author "Mamedov, Amirullah M."

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Band Structure and Optical Properties of Antimony-Sulfobromide: Density Functional Calculation
(versita, 2008) Akkus, Harun; Mamedov, Amirullah M.; Kazempour, Ali; Akbarzadeh, Hadi
The electronic structure, linear, and non-linear optical properties of ferroelectric-semiconductor SbSBr are investigated in the non-polar (paraelectric) and polar (ferroelectric) phase, using the density functional methods in the generalized gradient approximation. The electronic band structure obtained shows that SbSBr has an indirect forbidden gap of 2.16 and 2.21 eV in the paraelectric and ferroelectric phase, respectively. The linear photon-energy dependent dielectric functions and some optical functions, such as absorption and extinction coefficients, refractive index, energy-loss function, reflectivity, and optical conductivity in both phases and photon-energy dependent second-order susceptibilities in the ferroelectric phase are calculated. Moreover, some important optical parameters, such as the effective number of valence electrons and the effective optical dielectric constant, are calculated in both phases.
Band Structure and Optical Properties of Biocl: Density Functional Calculation
(Gazi Univ, 2012) Koc, Husnu; Akkus, Harun; Mamedov, Amirullah M.
The electronic band structures, density of states (DOS) and optical properties of BiOCl Crystal are investigated using the density functional theory under the local density approximation (LDA). The obtained electronic band structure show that BiOCl crystal has an indirect forbidden band gap of 2.45 eV. The structural optimization for BiOCl has been performed using the LDA. The result of the structure optimization of BiOCl have been compared with the experimental results and have been found to be in good agreement with these results. The linear photon-energy dependent dielectric functions and some optical properties such as the energy-loss function, the effective number of valence electrons and the effective optical dielectric constant are calculated.
Linear and Nonlinear Optical Susceptibilities in Some Ferroelectrics: Ab-Initio Calculation
(Unimap Press, 2010) Akkus, Harun; Cabuk, Suleyman; Mamedov, Amirullah M.
We present a first principles calculations of the second-order optical response functions as well as the dielectric function for ABO(3) (A=K, Li, Bo; B=Ti, Ta, Nb) and A(5)B(6)C(7) (A=Sb; B=S, Se; C=I, Br) ferroelectrics. Specially, we evaluate the dielectric function epsilon(omega) = epsilon(1)(omega)-i epsilon(2)(omega) and the second harmonic generation response coefficient chi((2)) (-2 omega, omega, omega, omega) over a large frequency range. The electronic linear electro-optic susceptibility chi((2))(-omega, omega, omega, 0) is also evaluated below band gap. These results are based on the series of self-consistent LDA calculations within DFT.