Browsing by Author "Dogan, Emel Kilit"

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Ab Initio Calculation of Physical Properties of Sodium Chloride
(Amer Scientific Publishers, 2013) Dogan, Emel Kilit; Secuk, Nurullah; Erdinc, Bahattin; Soyalp, Fethi; Akkus, Harun
We have calculated the structural, electronic, optical, dynamical, and thermodynamical properties of sodium chloride crystal using the density functional theory within the generalized gradient approximation. The calculated results for each physical property are presented and compared with available experimental data and previous theoretical data. There are controversial reports in the literature on the electronic band structure of sodium chloride. We especially present data and comments about this controversial subject.
Ab Initio Calculations of Structural, Electronic, Elastic, Optical, and Dynamical Properties of Half-Heusler Lisib Compound
(Springer, 2022) Akyuz, Gonul Bilgec; Dogan, Emel Kilit; Yurdasan, Nazli Boz; Tunali, Aylin Yildiz; Gulebaglan, Sinem Erden
Structural, electrical, elastic, optical, and dynamical properties of LiSiB half-Heusler compound were analyzed based on density functional theory implemented in Quantum Espresso and ABINIT package programs. The effects of exchange-correlation interactions are handled by the generalized gradient approximation with Perdew-Burke-Ernzerhof parametrization. Firstly, the structure of this half-Heusler compound has been optimized and our results indicate that LiSiB reveals semiconducting behavior with an indirect band gap of 0.21 eV. The elastic constants, and other elastic modules have been computed. The mechanical stabilities of these alloys have been theoretically confirmed. The phonon dispersion spectra and phonon density of states in the Brillouin zone have been obtained and discussed. Also, the optical properties were calculated, and the results showed that the LiSiB alloy has a strong optical transition and the LiSiB crystal could be used in the design of optoelectronic devices. There are no results found on elastic, optical, and phonon features of LiSiB in the literature; hence, the findings reported here shed light on future studies.
Ab-Initio Calculations of Physical Properties of Alkali Chloride Xcl (X = K, Rb and Li) Under Pressure
(Elsevier, 2015) Erdinc, Bahattin; Secuk, Mehmet Nurullah; Aycibin, Murat; Gulebagan, Sinem Erden; Dogan, Emel Kilit; Akkus, Harun
Structural properties, electronic band structure, real and imaginary parts of complex dielectric function of alkali chloride XCl (K, Rb and Li) compounds were investigated under various pressures using first principles calculations. Moreover, Gibbs free energies were also calculated at those pressures. Calculated results of the Gibbs free energy show that LiCl does not show any structural phase transition. However, structural phase transitions of KCl and RbCl occur from NaCl (B1) to CsCl (B2) at 4.5 and 1.7 GPa pressures, respectively. The electronic band gaps under pressure were also calculated. The calculated physical properties of these compounds are compared with the previous theoretical and experimental results and a good agreement was observed. (c) 2015 The Authors. Published by Elsevier B. V. This is an open access article under the CC BY-NC-ND license.
Ab-Initio Study of Csgecl3 Compound in Paraelectric and Ferroelectric Phases
(Taylor & Francis Ltd, 2016) Erdinc, Bahattin; Secuk, Mehmet Nurullah; Aycibin, Murat; Gulebagan, Sinem Erden; Dogan, Emel Kilit; Akkus, Harun
Structural optimization, electronic energy band structure, density of states, optical, lattice dynamic and thermodynamic properties of CsGeCl3 compound in paraelectric and ferroelectric phases were investigated using the DFT in the GGA and LDA approximations. The obtained results of CsGeCl3 crystal were compared with the available theoretical and experimental results and have been found to be in good agreement with these results.
Calculation of Electronic Band Structure of Ferroelectric Semiconductor Bismuth Niobium Oxyfluoride (Bi2nbo5f) Crystal
(Gazi Univ, 2014) Erdinc, Bahattin; McCabe, Emma; Duran, Duygu; Secuk, M. Nurullah; Gulebaglan, Sinem Erden; Dogan, Emel Kilit; Akkus, Harun
In this study, the geometric structural optimization, electronic band structure and density of states ( DOS) for electrons of ferroelectric Bi2NbO5F structure with space group Pca21 have been investigated using the density functional theory (DFT) under the local density approximation (LDA). The ground state properties of ferroelectric Bi2NbO5F structure are studied. The computed ground state properties and experimental results are consistent. The energy band structure of Bi2NbO5F compound below T-c shows that it is a ferroelectric semiconductor with narrow band gap of 0.0589 eV. Unfortunately, there is neither experimental nor theoretical electronic band structure study of Bi2NbO5F crystal in the literature, so we could not compare our results.
A Comparison Study of the Structural Electronic, Elastic and Lattice Dynamic Properties of Zrinau and Zrsnpt
(Walter de Gruyter Gmbh, 2021) Gulebaglan, Sinem Erden; Dogan, Emel Kilit
To estimate the structural, electronic, elastic and dynamic properties of ZrInAu and ZrSnPt compounds, the density functional theory within the general gradient approximation was used. The computed lattice parameters, bulk modulus and the derivation of bulk modulus with respect to pressure were displayed and compared with the theoretical result. The indirect band gap for ZrInAu was found to be 0.48 eV, and for ZrSnPt the indirect band gap was found as 1.01 eV. Elastic stiffness constants, bulk, shear and Young's module, Poisson's coefficients and Zener anisotropy factor are calculated. Elastic properties showed that the ZrSnPt compound is more durable than the ZrInAu compound. Phonon distribution curves and density of states were investigated using a density functional perturbation theory. Both ZrInAu and ZrSnPt compounds were demonstrated to be dynamically stable. The results of this study were obtained for the first time in the literature. These results will make an important contribution to the literature.
A Computational Estimation on Structural, Electronic, Elastic, Optic and Dynamic Properties of Li2tla (A=sb and Bi): First-Principles Calculations
(Elsevier Sci Ltd, 2022) Dogan, Emel Kilit; Gulebaglan, Sinem Erden
The structural, electronic, optic, elastic and dynamic properties of Li2TlSb and Li2TlBi full-Heusler structure are studied by first principles calculations. The plane wave pseudo-potential method with a generalized gradient approximation was used to calculate all these properties. Quantum Espresso program was used to examine structural, electronic and dynamic properties, and Abinit program was used to examine optical and elastic properties. The change correlation function chosen is the Perdew - Burke - Ernzerhof function. The currently calculated structural properties are in good agreement with other theoretical results. Based on the linear harmony of the stress-strain relationship, the elastic constants of these structures have been determined. Poisson's coefficients and Zener anisotropy factor, Bulk, Shear and Young Module are computed. With the density functional perturbation theory, the frequencies of the phonon distribution spectra throughout the entire brillouin region were calculated and all values were found to be positive. These results show that the dynamic stabilities of Li2TlBi and Li2TlSb crystals are strong. The results obtained in this study are thought to be useful in future scientific studies to explore the applications of these materials such as optoelectronic devices and sensors.
Investigation of Structural, Electronic, and Dynamic Properties of Half-Heusler Alloys Xcub (X = Ti, Zr) by First Principles Calculations
(Wiley-v C H verlag Gmbh, 2021) Gulebaglan, Sinem Erden; Dogan, Emel Kilit
In order to find out the structural, electronic, and dynamic properties of TiCuB and ZrCuB half-Heusler alloys, density functional theory within the generalized gradient approximation is used by Quantum Espresso package program. The lattice parameters, bulk modulus, first derivation of bulk modulus, electronic band structure, phonon dispersion curves, and phonon density of states are calculated for both half-Heusler alloys. Electronic band structure plots exhibit that these alloys are in semiconductor structure. Dynamic properties are investigated using a density functional perturbation theory. Phonon dispersion curves show that TiCuB and ZrCuB are dynamically stable alloys. Only the calculated lattice parameters can be compared with the literature, and it is noticed that they are in a good agreement. The rest of the obtained results cannot be compared with the literature since these calculations are performed for the first time in the literature with this study.
Investigation of the Complex Magnetic Behavior of Ni46.86co2.91mn38.17sn12.06 (At%) Magnetic Shape Memory Alloy at Low Temperatures
(Iop Publishing Ltd, 2022) Yildirim, Oguz; Yuce, Suheyla; Bruno, Nickolaus M.; Dogan, Emel Kilit; Yurtseven, Hamit; Duman, Eyup; Emre, Baris
The magnetic properties, martensitic transformation characteristics, the magnetic field-induced transformation characteristics, and super spin-glass behaviour at low temperature of Ni46.86Co2.91Mn38.17Sn12.06 (at%) magnetic shape memory alloys (MSMAs) were investigated under various magnetic field levels over temperature intervals from 400 K to 10 K. We observe a small magnetization difference during the martensitic transition evidenced with a visible thermal hysteresis. To investigate the magnetic field induced phase fraction, the minimum magnetic field required to start and complete the magnetostructural phase transition is computed. Super-spin glass features in magnetic data are observed that interacting magnetic clusters are frozen below a critical temperature. Magnetization is computed as a function of temperature at various constant fields using molecular field theory. The critical exponent, beta is deduced for the temperature-induced magnetization, which indicates that the MSMA exhibited ferromagnetic ordering during field-cooling and on heating an antiferromagnetic ordering at low temperatures and in low applied magnetic fields. These observations are consistent within the framework of an Ising or Heisenberg model.
Lattice Dynamics and Electronic Properties of Heusler Alloys Li2alx (X=ga, In): a Comparison Study
(Chinese Physical Soc, 2021) Dogan, Emel Kilit; Gulebaglan, Sinem Erden
The lattice parameters, bulk modulus, first derivative of the bulk modulus, electronic band structures, phonon dispersion curves and phonon density of states calculations for Li2AlGa and Li2AlIn Heusler alloys are performed and compared in this study using density functional theory within the generalized gradient approximation. Computed lattice parameters display a good agreement with the literature. Obtained electronic band structures of both Heusler alloys show that they are in semi-metallic structure. Phonon dispersion curves and the phonon density of states graphs are also obtained in order to study the lattice dynamics of these Heusler alloys. It is noticed that Li2AlGa and Li2AlIn Heusler alloys are dynamically stable in the ground state.
Physical Properties of Rbau Compound
(Elsevier Science Bv, 2014) Aycibin, Murat; Dogan, Emel Kilit; Gulebaglan, Sinem E.; Secuk, M. Nurullah; Erdinc, Bahattin; Akkus, Harun
In this paper, we investigated electronic, optic, elastic, dynamic and thermodynamic properties of RbAu compound by density functional theory within the generalized gradient approximation. The calculated static value of real part of dielectric constant is 6.7. The calculated electronic band structure of RbAu shows that RbAu is a semiconductor with an indirect band gap of 0.36 eV. Besides, RbAu obeys mechanical stability and it demonstrates elastic anisotropy. 540K is classical limit for specific heat of RbAu. (C) 2014 The Authors. Published by Elsevier B.V.
Prediction the Structural, Electronic, Elastic and Dynamical Properties of Lialge and Liinge Half-Heusler Crystals by Density Functional Theory
(Elsevier, 2022) Gulebaglan, Sinem Erden; Dogan, Emel Kilit
In the present study, structural, electronic, elastic and vibrational properties of LiInGe and LiAlGe half-Heusler compounds are investigated using density functional theory implemented in ABINIT and Quantum ESPRESSO programs. Generalized gradient approximation as an exchange correlation functional is used in Kohn-Sham equations to find lattice parameters, energy band gaps and three elastic constants C-11, C-12 and C-44 for LiInGe and LiAlGe crystals. Density functional perturbation theory has been adopted in the study of lattice dynamics. As a result of the calculations, it is concluded that the phonon dispersion curves have positive frequency values throughout the entire Brillouin region and the dynamic stability of both crystals is strong. It is estimated as a result of calculations that this stabilization is impaired at a pressure value of approximately 492.65 kbar for LiInGe crystal and approximately 962.16 kbar for LiAlGe crystal.
Some Properties of Liinsi Half-Heusler Alloy Via Density Functional Theory
(indian Acad Sciences, 2021) Dogan, Emel Kilit; Gulebaglan, Sinem Erden
In this study, structural, electronic, elastic and dynamic properties for LiInSi in the half-Heusler structure were analysed with the generalized gradient approximation using the density functional theory. The results obtained are compatible with the structural and electronic properties in literature. In addition to the results related to electronic properties in literature, cohesive energy and formation energy values were calculated. These values were found to be 10.333 and -0.884 eV, respectively. Elastic constants, bulk, shear, Young's moduli, Poisson's coefficient and Zener anisotropy factor values of LiInSi alloy were revealed. In addition, using linear phonon theory, phonon dispersion curve and phonon density of states graph were obtained. It has been calculated that while the LiInSi alloy is dynamically stable in the ground state, it becomes unstable under nearly 615 kbar pressure. Elastic and dynamic properties are presented in literature for the first time. It is expected that these results will be a guide for future studies.
Structural Electronic and Dynamic Properties of Li3bi and Li2nabi
(Iop Publishing Ltd, 2020) Gulebaglan, Sinem Erden; Dogan, Emel Kilit
We report a study of structural, electronic and dynamic properties of Li3Bi and Li2NaBi via density functional theory. It is found that Li3Bi and Li2NaBi show semiconducting property with an indirect electronic band gap. The calculated structural and electronic parameters (lattice parameters, bulk modulus, bulk modulus derivation) are in a good agreement with the available experimental data. Full phonon spectra of Li3Bi and Li2NaBi materials in the Rock Salt structure were collected using the linear response method. At 0 GPa pressure, Li3Bi is dynamically stable while Li2NaBi, which can be synthesized from Li3Bi by replacing one Bi atom with the Na atom, is unstable. In this study we searched to find the pressure value that makes Li2NaBi dynamically stable. Calculations showed that the Li2NaBi structure becomes stable when 8.62 GPa pressure is applied to the Li2NaBi structure. This study is thought to give direction to the future studies.
Theoretical Insight on the Structural, Electronic, Elastic, Optical and Vibrational Properties of Ligasi Half-Heusler Crystal for Ground State and Under Pressure
(Springer, 2025) Gulebaglan, Sinem Erden; Dogan, Emel Kilit
In this study, the electronic, structural, optical, elastic and dynamic properties of LiGaSi half- Heusler crystalline were tried to be predicted for the ground state and under pressure by using density functional theory. Quantum Espresso and Abinit software programs were used while carrying out this research. While performing calculations in these package programmings, the Generalized Gradient Approximation was taken into consideration. Calculations showed that the critical pressure value for LiGaSi half-Heusler crystal is estimated to be approximately 935 kbar. It was noticed that the LiGaSi half-Heusler crystal, while a brittle material in the ground state, became an elastic material under pressure. Additionally, it was concluded that while LiGaSi half-Heusler crystal is dynamically stable in the ground state, LiGaSi half-Heusler is dynamically unstable under 935 kbar pressure. This has additionally been shown to make it more thermally conductive. It is thought that the results obtained from this study and the information obtained by interpreting the results will contribute to the literature and will be useful for future studies.