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Öğe AB-INITIO CALCULATIONS OF STRUCTURAL, ELECTRONIC AND MAGNETIC PROPERTIES OF LiRh2Si2(Bilal GÜMÜŞ, 2018) Balcı, Gülten Kavak; Ayhan, SeyfettinAbstract In this study, we investigated the structural, electronic and magnetic properties of the tetragonal LiRh2Si2 using the full-potential linearized augmented plane wave (FP-LAPW). The structural calculations were performed with four exchange and correlation potential (GGA- PBE, LDA-PW, GGA-WC and GGA-PBEsol), the electronic and magnetic properties were performed with GGA-PBE implemented in Wien2k code. We have obtained the cell dimensions, bulk modulus, and its pressure derivative. The calculated lattice parameters are in good agreement with experimental and previous theoretical results. We calculated cohesive energy as 4,95 eV/atom and LiRh2Si2 has good stability. Electron density plot of LiRh2Si2 shows strong covalent interactions between Si-Si and Rh-Si elements. We performed spin polarize calculation of Density of States (DOS). Electronic band chart that show LiRh2Si2 has metallic feature for both spin up and spin down configurations. The spin up and spin down electronic band chart nearly symmetric so the compounds has nonmagnetic feature. We searched pressure effect on magnetic moment of LiRh2Si2. The magnetic moment of LiRh2Si2 has been found 0.00075 () and it decreased with increase of pressure.Öğe Ab-initio calculations of structural, electronic, and magnetic properties of Li based heusler compounds(Nova Science Publishers, Inc., 2024) Balci, Gulten Kavak; Ayhan, SeyfettinIn today's technology, the basic properties of these materials must be known to benefit from the material that is produced artificially or exists naturally. The material properties of atoms or molecules can be calculated both experimentally and theoretically. Every new research contributes to improving data and new methods that cost less. Schrodinger equation of the structure of atoms and molecules needs to be resolved to determine the physical properties of these systems. However, for a small number of systems it can be analytically solved and for a few systems numerical solutions can be made. In addition, the Schrodinger equation's analytical or numerical solution is not possible for a many-body system because of electron-electron and electron-core interaction. Therefore, some methods are used to analyze the many-body systems. These methods can be listed as the Wave Functions method, Green's Functions method, and density functional theory (DFT). Here, we will focus on the development of density functional theory. The calculation of the electronic structure of crystal structures is made using computer software packaged programs such as ABINIT, SIESTA, VASP, and Wien2k, which are based on Kohn-Sham equations and Ab-initio methods that enable exact solutions of quantum mechanical ground states of electron systems. In this study, the structural, electronic, and magnetic properties of Libased structures will be determined using the density functional theorybased package program called the Wien2k. © 2024 Nova Science Publishers, Inc. All rights reserved.Öğe Ab-initio calculations of structural, optical and electronic properties of AgBiS2(2018) Balcı, Gülten Kavak; Ayhan, SeyfettinIn this work, we use first-principles calculations based on density-functional theorygeneralized gradient approximation (Perdew Burke Ernzerhof, PBE). Cubic and hexagonalAgBiS2 structures have been performed using the self-consistent full-potential linearizedaugmented plane wave (FPLAPW) method to investigate the structural, optical and electronicproperties. We have calculated the ground-state energy, the lattice constant, DOS, band gapand dielectric constant of cubic and hexagonal AgBiS2 by using Wien2k packet. The calculatedphysical properties of silver bismuth sulfide are compared with the experimental results andgood agreement was observed.Öğe Ab-initio calculations: structural, electronic and elastic properties of LiX2Ge (X: Rh, Cu, Ni, Pd) Heusler compounds(Iop Publishing Ltd, 2019) Ayhan, Seyfettin; Balci, Gulten KavakIn this study, the structural, electronic and elastic properties of LiX2Ge (X: Rh, Cu, Pd, Ni) Heusler phase compounds were investigated with density functional theory based on the FP-LAPW method implemented in a Wien2k package. PBE-GGA was used as an exchange and correlation potentials. The lattice constants, total energy, bulk modulus and cohesive energy of these compounds were determined. The density of states (DOS), electronic band gap and electron density were depicted. All compounds were revealed the metallic feature. The elastic properties of these structures were investigated employing the cubic-elastic code developed by Jamal and elastic code developed by Golesorkhtabar et al. The elastic constants, bulk modulus, Young's modulus, shear modulus, Poisson's ratio, Debye temperature, and elastic anisotropy factor of all compounds were calculated. It is concluded that all the structures were mechanically stable because they confirmed to Born's criteria. These results were also found to be in good agreement with previous studies and experimental data.Öğe Half-Metallic Ferromagnetism in Co2NiSi Full-Heusler Compound(Amer Inst Physics, 2018) Ayhan, Seyfettin; Balci, Gulten KavakIn this work, half-metallic (HM) properties of new Full-Heusler ferromagnetic compound Co2NiSi were studied by means of first principle band structure calculation within the framework of density functional theory (DFT). The structural calculations were performed with PBE-GGA (Perdew, Burke and Ernzerhof) potential. The magnetic and electronic properties were performed with Modified Becke-Johnson potential (mBJ). From the spin-polarized calculations using full-potential linearized augmented plane-wave (FP-LAPW) method, we have investigated structural, electronic and magnetic properties of Co2NiSi compound with both AlCu2Mn and CuHg2Ti structure type. Both compounds are metallic with spin up and have bandgap with spin down configuration. Total magnetic moment of Co2NiSi is calculated 3.07 B and 3.28 B for AlCu2Mn and CuHg2Ti structure type, respectively. The compounds has band gap below to Fermi level with 0.2 eV. So we found the Co2NiSi shows type III half metallic behavior.Öğe n-Si/metal kompleksi/Au yapıların aygıtsal özellikleri ve panaf metal kompleksinin optiksel özelliğinin araştırılması(2015) Ayhan, SeyfettinBu çalışmada Dicle Üniversitesi kimya bölümü tarafından sentezlenen Panaf ligandının[N,Nı-bis-(2-hidroksinaftalin-1-karbaldehiden)-1,2-bis-(p-aminofenoksi)etan)] bakır(II)kompleksi Au/n-Si/Cu-Panaf kompleksi/Au yapıda arayüzey olarak kullanıldı. Elde edilen yapının I-V ve C-V ölçümlerinden elektriksel özellikleri belirlendi. Bu ölçümlerden Au/n-Si/Cu-Panaf kompleksi/Au yapının ideal olmayan doğrultucu özellik gösterdiği tespit edildi. Bu yapının güneş simülatörü altında I-V ölçümleri alındı. Elde edilen verilerden aygıtın fotodiyot özellik gösterdiği anlaşıldı. Panaf bakır kompleksi Spin Coater ile kuvars üzerinde ince film haline getirildi. Hazırlanan ince filmlerin UV-VIS ölçümleri ile absorbsiyon ve geçirgenlik verileri dalga boyuna bağlı olarak elde edildi. Elde edilen veriler kullanılarak maddenin yasak enerji aralığı Eg = 4,5 eV olarak hesaplandı.Öğe Physical Properties of Magnesium Nitridophosphate (Mg2PN3) Compound(Amer Inst Physics, 2018) Ayhan, Seyfettin; Balci, Gulten KavakIn this work, we investigated structural, electronic and optical properties of orthorhombic Mg2PN3 compound. The calculations were performed with full-potential linearized augmented plane-wave (FP-LAPW) method based on Density Functional Theory by using Wien2k packet. PBE-GGA (Perdew, Burke and Ernzerhof) were selected as exchangecorrelation functional. We calculated cell dimensions, bulk modulus and cohesive energy of this compound. The calculated structural parameters have good agreement with experimental works. We calculated DOS curve, electronic band structure, dielectric function, absorption coefficient and optical conductivity parameters. The DOS and electronic band calculations show that Mg2PN3 has indirect band gap with 5.2 eV value.Öğe Yoğunluk fonksiyoneli teorisi (YFT) kullanılarak LiX2Y (X:Rh, Cu, Pd, Ni; Y: Ge, Si) Heusler yapıların yapısal, elektronik ve manyetik özelliklerinin incelenmesi(2018) Ayhan, Seyfettin; Kavak Balcı, GültenBu tezde LiX2Y (X:Rh, Ni, Cu, Pd; Y: Si, Ge) Heusler fazlı sekiz adet bileşiğin yapısal, elektronik ve manyetik özelliği Yoğunluk Fonksiyoneli Teorisi, FPLAPW metodu ile WIEN2K kodu kullanılarak araştırıldı. Yapısal optimizasyon dört farklı potansiyel (PBE-GGA, WC-GGA, LDA ve PBEsol) seçeneğine bağlı olarak yapıldı. Yapısal optimizasyondan bileşiklerin birim hücre parametreleri, toplam enerjisi ve bulk modülü belirlendi. Farklı potansiyeller için hesaplanan birim hücre parametreleri birbiri ve deneysel veriler ile karşılaştırıldığında en iyi sonucu PBE-GGA potansiyelinin verdiği görüldü. Yapıların durum yoğunluğu eğrisi ve elektronik bant grafiği spin yönelimine bağlı olarak çizildi. Tüm yapıların her iki spin yönelimi için metalik özellik gösterdiği anlaşılmaktadır. İncelenen örneklerin hiçbiri yarı metalik özellik göstermedi. Bileşiklerin manyetik özelliğini belirlemek için PBE-GGA potansiyel seçiminde spin polarize hesaplama yapıldı ve yapıların manyetik momenti elde edildi. Yapıların toplam manyetik momentinin küçük değerler aldığı görülmektedir. Deneysel veriler ile yapılan hesaplamalara göre LiRh2Ge, LiRh2Si ve LiPd2Si bileşikleri diamanyetik özellik gösterirken LiPd2Ge, LiCu2Ge, LiCu2Si, LiNi2Si ve LiNi2Ge paramanyetik özellik göstermektedir. Yapıların elastik özellikleri M. Jamal tarafından yazılan cubic-elastic kodu kullanılarak incelendi. Yapıların elastik sabitleri, bulk modülü, young modülü, kesme modülü ve poisson oranı hesaplandı. Tüm yapıların Born kararlılık şartına uyduğu dolayısıyla mekanik olarak kararlı olduğu görüldü. Elde edilen sonuçların deneysel veriler ve önceki çalışmalar ile uyumlu olduğu görülmektedir. Anahtar Kelimeler: Heusler, Yoğunluk Fonksiyoneli Teorisi, Yapısal Özellikler, Manyetik Özellikler, Elektronik Özellikler, Elastik Özellikler
