Maryam Goudarzi; sara sadat parhizgar; javad Beheshtian
Abstract
Structural and electronic properties of Iron oxide clusters (Fe2O3, Fe3O4, Fe4O6 and Fe6O9) and change this properties in bilayer graphene Due to placement of clusters between two layer of graphene have been investigated computationally using density functional theory (DFT). We find that By placing the ...
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Structural and electronic properties of Iron oxide clusters (Fe2O3, Fe3O4, Fe4O6 and Fe6O9) and change this properties in bilayer graphene Due to placement of clusters between two layer of graphene have been investigated computationally using density functional theory (DFT). We find that By placing the studied clusters between two layers of graphene, graphene layers and clusters, which are initially neutral, are electrically charged, and their charges are equal in opposite sign. Also by placing the clusters between the two graphene layers, the resulting structures are magnetic, and total spin is equal to the cluster spin between the two graphene layers. so by placing Fe2O3, Fe3O4 and Fe4O6 clusters between two graphene layers, a chemical bond is formed between them and graphene layers, while the adsorption Fe6O9 cluster between two graphene layers is a physical adsorption.Keywords: Density Functional Theory, Bilayer Graphene, Iron Oxide clusters, Structural and Optical properties
Seyed Mohammad Ghazi; Fahimeh Behzadi
Abstract
In this article, a theoretical study has been done using quantum calculations in the framework of density functional theory on the stability of structures, electronic properties and vibrational frequencies of sodium nanoclusters Na_n (n=10-48). By calculating the coordination number, it was determined ...
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In this article, a theoretical study has been done using quantum calculations in the framework of density functional theory on the stability of structures, electronic properties and vibrational frequencies of sodium nanoclusters Na_n (n=10-48). By calculating the coordination number, it was determined that the first motif that is created and repeated in these nanoclusters is an icosahedron, and as the number of atoms increases, the number of these icosahedra is also increased. The second difference of energy and the gap between the last occupied level and the first unoccupied level show that the more stable nanoclusters have an even number of electrons and also have a more spherical shape than the rest of them. The two sharp peaks in the second difference of energy diagram are related to Na_20 and Na_40 respectively, which indicate the greater stability of these two nanoclusters compared to the others and also match the magic numbers.In terms of geometrical shape, the nanoclusters were divided into 4 categories using the shape deformation parameter, and their correlation and relationship with the infrared intensity spectrum was investigated
khodarahm ghandi; Seyyed Mahdy Baizaee
Abstract
In this research, the structural features, electronic and magnetic properties of armchair (5, 5) indium phosphide nanotube doped with Cr, Co, Cu and Zn have been investigated using first principles calculations. Calculations were performed by the PWscf code using a density functional theory. The metals ...
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In this research, the structural features, electronic and magnetic properties of armchair (5, 5) indium phosphide nanotube doped with Cr, Co, Cu and Zn have been investigated using first principles calculations. Calculations were performed by the PWscf code using a density functional theory. The metals Cr, Co, Cu and Zn were replaced by P atomic position in this nanotube. The optimal angles between them and the bond length were calculated. The calculations illustrate that there is a structural distortion around Cr and Co impurities, and also show that the magnetic moments are consistent with the predicted value of Hund’s rule. Furthermore, the observations revealed that the indium phosphide nanotube doped with Cr and Co is a ferromagnetic metal, while the indium phosphide nanotube doped with Cu and Zn is a non-magnetic metal. The present results predict that indium phosphide nanotubes doped with Cr and Co are useful for industrial applications in Nano magnets. To identify the most stable configuration, the binding energy and the cohesive energy were calculated for all compounds. Finally, our results show that the InP nanotube doped with Cobalt is more stable than others
Fateme Karami; Ahmad Asadi Mohammad Abadi
Abstract
In this research, the electronic, magnetic and optical properties of inverse Heusler alloys Ti2ScX (X=Si,Sn) were studied using the Quantum Espresso software package based on the density functional theory. The results of the electronic properties investigation showed that both alloys are half-metals ...
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In this research, the electronic, magnetic and optical properties of inverse Heusler alloys Ti2ScX (X=Si,Sn) were studied using the Quantum Espresso software package based on the density functional theory. The results of the electronic properties investigation showed that both alloys are half-metals in their equilibrium lattice constant and exhibit 100% spin polarization around the Fermi level. The indirect half-metallic band gap for Ti2ScSi and Ti2ScSn alloys were obtained as 0.35eV and 0.11eV, respectively. Furthermore, considering the high values of the Curie temperature of Ti2ScX (X=Si, Sn) alloys, it can be concluded that these alloys are stable at room temperature. Analyzing magnetic properties revealed that Ti2ScX (X=Si,Sn) alloys exhibit ferromagnetic behavior in their stable structure, and their total magnetic moment is 7µB/f.u., which is in good agreement with the Slater-Pauling rule. Consequently, it can be inferred Heusler alloys Ti2ScX (X=Si,Sn) are half-metal ferromagnetism. Additionally, the optical properties of these alloys suggest their potential as electromagnetic waves absorbers.
Ahmad Asadi Mohammad Abadi; Seyyed Mahdy Baizaee
Abstract
In this study, the structural, electronic and magnetic properties of new full Heusler alloys Ir2VZ (Z = Si, Ge, Sn) were studied using the Quantum Espresso software package based on density functional theory. Interchanging the positions of atoms, the calculations were performed for two hypothetical L21 ...
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In this study, the structural, electronic and magnetic properties of new full Heusler alloys Ir2VZ (Z = Si, Ge, Sn) were studied using the Quantum Espresso software package based on density functional theory. Interchanging the positions of atoms, the calculations were performed for two hypothetical L21 and XA structures. The results showed that, the XA structure of alloys was non-magnetic, while the L21 structure of these alloys was ferrimagnetic. Based on investigation of structural properties of these alloys, it was found that the Ir2VSi alloy is more stable than the other two alloys due to its lowest cohesive energy. Also, the results of calculations on electronic properties show that Ir2VSi, Ir2VGe and Ir2VSn alloys are half-metall, quasi half-metall and metall at equilibrium lattice constants, respectively. Thus Ir2VSi alloy has 100% spin polarization around the Fermi level and its total magnetic moment (3µB/f.u.) exactly follows Slater-Pauling rule.
Seyyed Mojtaba Alavisadr; Zohreh Dadigiv
Abstract
In the present work, by using the first-princilpes calculations within the density functional theory framework, the structural, electronic and magnetic properties of AlCu2Mn and CuHg2Ti crystal structures of the full-Heusler compound Co2TaGa were studied. The results indicate that the ground state of ...
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In the present work, by using the first-princilpes calculations within the density functional theory framework, the structural, electronic and magnetic properties of AlCu2Mn and CuHg2Ti crystal structures of the full-Heusler compound Co2TaGa were studied. The results indicate that the ground state of this compound is AlCu2Mn-Type with ferromagnetic order and a magnetic moment of 2.00µB. The results of electronic structure calculations show that the ground state has a half-metallic nature with an energy gap of 0.48eV and 100% spin polarization. According to the results of this study, the Co2TaGa Heusler compound can be recommended as a novel material for future aims in spintronic applications.
Syed Ali Hashemizadeh (Ph.D.); Maryam Masoudi; Masomeh Arabikhah; Zahra Abasi Azad
Volume 2, Issue 2 , June 2019, , Pages 25-32
Abstract
In this study, optical properties of BaTiO3/SrTiO3/CaTiO3 compounds such as reflective index, extinction coefficient, absorption coefficient, reflectivity, energy loss spectrum and optical conductivity have been calculated and investigated in their stable phases, rhombohedral/ cubic/ orthohorombic phase ...
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In this study, optical properties of BaTiO3/SrTiO3/CaTiO3 compounds such as reflective index, extinction coefficient, absorption coefficient, reflectivity, energy loss spectrum and optical conductivity have been calculated and investigated in their stable phases, rhombohedral/ cubic/ orthohorombic phase with p4mm/m3m/pbnm space group respectively. The calculations have been conducted with pseudo-potential by GGA approximation in the frame work of Density Functional Theory. The obtained results for constant lattice after optimization, static dielectric constant, reflective index and plasma frequency have good accord with the experimental results and other theoretic studies. With respect to these quantities, perovskite oxides are good dielectrics. With respect to dielectic constants, and suitable optical absorbtion in the range of 4-12 eV, these perovskite oxides are good dielectrics. These compounds are transparent in energies above 13eV,and the maximum amount of conductivity occurs within 5eV. Also D coefficient calculated by Gladstone-Dale equation.
Samin Ebrahimi; Seis Ali Hashemizadeh-aghda
Volume 1, Issue 1 , May 2016, , Pages 21-28
Abstract
In this article, optic properties of AlInGaN compounds such as real and imaginary part of dielectric function, optical conductivity, refractive index and extinction index have been investigated. Calculation have performed using Full Potential Linear Approximation Plane Wave method inDensity Functional ...
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In this article, optic properties of AlInGaN compounds such as real and imaginary part of dielectric function, optical conductivity, refractive index and extinction index have been investigated. Calculation have performed using Full Potential Linear Approximation Plane Wave method inDensity Functional Theory framework by WIEN2K package.
Finally, the optical properties of these compounds were examined which confirmed the results of the electronic and band structures. We also noticed that the VBM of these alloys is higher than the GaN in the fixed band gap. So it is expected that these alloys are doped much easier than P-type semiconductors.