Browsing by Author "Akkus, H."

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Electronic, Optic and Dynamic Properties of Rhombohedral Bitebr
(Iop Publishing Ltd, 2016) Secuk, M. N.; Akkus, H.
Electronic, optic and thermodynamic properties of rhombohedral BiTeBr crystal were investigated under the local density approximation (LDA) using the density functional theory. No spin-orbit interaction (SOI) were taken into account during calculations and band gap of 0.946 eV was found as which is different from experimental results but in good agreement with previous theoretical studies without SOI. For this new type ferroelectric BiTeBr from ground states features lattice parameters, electronic total density of states (TDOS), partial density of states (PDOS) and electronic band structure, from optical properties dielectric function, refraction index, extinction, reflection and absorption coefficients, number of effective valance electrons, volume and surface loss functions, among thermodynamic properties change in Helmholtz free energy, internal energy, entropy and constant volume specific heat as a function of temperature were studied.
Structural, Thermodynamic and Phonon Properties of Sbsi and Sbsbr Single Crystals
(Korean Physical Soc, 2013) Dogan, E. Kilit; Aycibin, M.; Gulebaglan, S. Erden; Secuk, M. N.; Erdinc, B.; Akkus, H.
The structural, dynamical and thermodynamic properties of antimony sulfoiodide (SbSI) and antimony sulfobromide (SbSBr) are investigated by using an ab-initio pseudopotential method applying density functional theory (DFT) within the local density approximation (LDA). The dynamical properties, such as the phonon dispersion and the phonon density of states, are calculated. Making a factor group analysis we classify the phonon modes. Moreover, the thermodynamic properties, such as the entropy and the constant-volume specific heat, as functions of temperature and the phonon contribution to the free energy and the internal energy are calculated.
Theoretical Study of Rhombohedral Nacaf3 Crystal in the Predicted Ferroelectric Phase
(Gazi Univ, 2014) Erdinc, B.; Aycibin, M.; Secuk, M. N.; Gulebaglan, S. E.; Dogan, E. K.; Akkus, H.
The calculated results for structural optimization, electronic band structure, total density of states and optical properties of a rhombohedral NaCaF3 compound were discussed using generalized gradient approximation under the density functional theory. According to our calculation, NaCaF3 crystal has a direct band transition. Moreover, optical properties of NaCaF3 were investigated using scissor approximation. This is the first theoretical study of rhombohedral crystal structure of NaCaF3 as far as we know.