The Electronic Band Structure and Vibrational Properties of Cubic BxIn1-xN Alloy

2013 ◽  
Vol 446-447 ◽  
pp. 98-103
Author(s):  
Nnamdi Omehe ◽  
Divine Ojuh
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Band Structure Calculation ◽  
Gw Approximation ◽  
Electronic Band ◽  
Phonon Band ◽  
Zone Centre ◽  
Indirect Band Gap

We have performed the electronic and phonon band structures of BxIn1-xN for various concentration of Boron using the pseudopotential method. The electronic band structure calculation was done using the GW approximation while the phonon band structure was done using the density functional perturbation theory. All calculations were done within the frame work of the density functional theory (DFT). From our calculations, the direct band gap for B0.25In0.75N, B0.5In0.5N and B0.75In0.25N were found to be 0.024eV, 2.2 eV and 6.01 eV respectively while the indirect band gap obtained were 0.59 eV, 3.24 eV and 6.9 eV. For the phonon calculations, it was also observed that an increase in the Boron content results in corresponding increase in the frequency of the topmost LO at the zone centre. For B0.25In0.75N, B0.5In0.5N and B0.75In0.25N, the topmost LO obtained were 735 cm-1, 885 cm-1 and 1105 cm-1 respectively. We also saw that as the Boron concentration decreases, the number of optical bands across which the acoustic bands overlap increases.

scholarly journals DFT COMPUTATION OF THE BAND STRUCTURE AND DENSITY OF STATE FOR ZnO HALITE STRUCTURE USING FHI-aims CODE.

2020 ◽  
Vol 4 (2) ◽  
pp. 490-498
Author(s):  
M. A. Adamu ◽  
K. Lawal ◽  
K. Lawal ◽  
A. Saminu
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Research Work ◽  
Basis Sets ◽  
Band Structure Calculation ◽  
Density Of State ◽  
Electronic Band

This research work is on Density Functional Theory (DFT) within Local Density Approximation as parameterised by Perdew and Wang (pw-lda).The calculation was performed using Fritz Haber Institute Ab-initio Molecular Simulations (FHI-aims) code based on numerical atomic-centered orbital basis sets. The electronic band structure, density of state (DOS) and band gap energy were calculated for ZnO compound. The band structure and Density of States (DOS) diagrams are plotted from the calculated equilibrium lattice parameters. The experimentally lattice constant values were used to calculate the minimum total energy. The calculated electronic band structure results show that ZnO (Halite) is an indirect semiconductor with energy band gap of 0.89 eV. Hence, the HOMO is -0.863382 eV at L_symmetry point and LUMO is 0.0239417 eV at ᴦ- point. The DOS energy level within the compound shows considerable high state of electron occupation and the DOS observed around the Fermi level at zero level indicate that it has conducting properties. In general, FHI-aims code has shown better accuracy and prediction of band structure calculation within reasonable computational methods.

scholarly journals Structural, Electronic and Vibrational Properties of YAl3(BO3)4

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 545 ◽  
Author(s):  
Aleksandr S. Oreshonkov ◽  
Evgenii M. Roginskii ◽  
Nikolai P. Shestakov ◽  
Irina A. Gudim ◽  
Vladislav L. Temerov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Band Gap ◽  
Density Functional ◽  
Dielectric Material ◽  
Electronic Band Structure ◽  
Vibrational Properties ◽  
Electronic Band ◽  
Functional Theory ◽  
Dynamical Properties ◽  
Indirect Band Gap

The crystal structure of YAl3(BO3)4 is obtained by Rietveld refinement analysis in the present study. The dynamical properties are studied both theoretically and experimentally. The experimental Raman and Infrared spectra are interpreted using the results of ab initio calculations within density functional theory. The phonon band gap in the Infrared spectrum is observed in both trigonal and hypothetical monoclinic structures of YAl3(BO3)4. The electronic band structure is studied theoretically, and the value of the band gap is obtained. It was found that the YAl3(BO3)4 is an indirect band gap dielectric material.

Electronic Band Structure of Cubic Silicon Carbide Nanowires

2008 ◽  
Vol 600-603 ◽  
pp. 575-578 ◽  
Author(s):  
A. Miranda ◽  
A. Estrella Ramos ◽  
M. Cruz Irisson
Keyword(s):  
Silicon Carbide ◽  
Band Structure ◽  
Band Gap ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Thickness Variation ◽  
Hydrogen Atoms ◽  
Electronic Band ◽  
Cubic Silicon Carbide

In this work, the effects of the diameter and morphology on the electronic band structure of hydrogenated cubic silicon carbide (b-SiC) nanowires is studied by using a semiempirical sp3s* tight-binding (TB) approach applied to the supercell model, where the Si- and C-dangling bonds on the surface are passivated by hydrogen atoms. Moreover, TB results (for the bulk) are compared with density functional calculations in the local density approximation. The results show that though surface morphology modifies the band gap, the change is more systematic with the thickness variation. As expected, hydrogen saturation induces a broadening of the band gap energy because of the quantum confinement effect.

Establishment of Structural and Elastic Properties of Titanate Compounds Based on Pb, Sn and Ge by First-Principles Calculation

2014 ◽  
Vol 510 ◽  
pp. 57-62 ◽  
Author(s):  
N.H. Hussin ◽  
M.F.M. Taib ◽  
N.A. Johari ◽  
F.W. Badrudin ◽  
O.H. Hassan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Computer Code ◽  
Lattice Parameter ◽  
First Principles Calculation ◽  
Electronic Band ◽  
Equilibrium Lattice Parameter ◽  
Indirect Band Gap

Structural, electronic, and optical properties of PbTiO3, SnTiO3, and GeTiO3 tetragonals (P4mm, 99 space group) were investigated using density functional theory as implemented in pseudo-potential plane wave in CASTEP computer code. The calculated equilibrium lattice parameter, electronic band structure, and optical properties for PbTiO3 (reference compound) are in good agreement with the available experiment data. The result also shows that GeTiO3 has a higher tetragonality (c/a=1.18) compared with SnTiO3 (c/a=1.15) and PbTiO3 (c/a=1.05). Calculations of the elastic constants of PbTiO3, SnTiO3, and GeTiO3 tetragonals show that they are mechanically stable. The electronic band structure shows that PbTiO3 has higher indirect band gap at X-G compared with SnTiO3 and GeTiO3, as explained in detail by the optical properties of ATiO3 (A=Pb, Sn, Ge) through the refractive index and absorption coefficient.

Effect of Al Excess on the Band Structure of ZnO Using Density Functional Theory

2016 ◽  
Vol 857 ◽  
pp. 106-110
Author(s):  
J.H. Lim ◽  
Cheow Keat Yeoh ◽  
Abdullah Chik ◽  
Pei Leng Teh
Keyword(s):  
Electrical Conductivity ◽  
Density Functional Theory ◽  
Band Structure ◽  
Band Gap ◽  
Density Functional ◽  
Band Structure Calculation ◽  
Al Doping ◽  
Electronic Band ◽  
Functional Theory ◽  
Doped Zno

The effect of Al doping to the band structure of ZnO was studied in this paper. The electronic band structure of Al doped ZnO was determined by using first-principles based on density functional theory. ABINIT was used to perform the band structure calculation. The calculated band structure of ZnO and Al doped ZnO shows that ZnO is a direct band gap semiconductor. The band structure become narrow with Al doping compared pure ZnO. With Al doping, the band gap of ZnO (0.749 eV) become smaller as the concentration Al doping increased to 4wt% (0.551 eV). The electrical conductivity of Al doped ZnO was studied as a references value for the band gap. The electrical conductivity of ZnO (8.21 S/cm) was enhanced with Al doping increased to 4wt% (71.87 S/cm).

scholarly journals Ab initio calculations of electronic band structure of CdMnS semimagnetic semiconductors

Doklady BGUIR ◽  
2022 ◽  
Vol 19 (8) ◽  
pp. 45-49
Author(s):  
M. А. Mehrabova ◽  
N. T. Panahov ◽  
N. H. Hasanov
Keyword(s):  
Crystal Structure ◽  
Band Structure ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Band Gap ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Spin Density Approximation ◽  
Electronic Band ◽  
Semimagnetic Semiconductors

This work is devoted to theoretical investigations of Cd1-xMnxS semimagnetic semiconductors (SMSC). The purpose of this work was to calculate the electronic band structure of ideal and defective Cd1- xMnxS SMSC in both antiferromagnetic (AFM) and ferromagnetic (FM) phases. Ab initio, calculations are performed in the Atomistix Toolkit (ATK) program within the Density Functional Theory (DFT) and Local Spin Density Approximation (LSDA) on Double Zeta Double Polarized (DZDP) basis. We have used Hubbard U potential UMn = 3.59 eV for 3d states for Mn atoms. Supercells of 8 and 64 atoms were constructed. After the construction of Cd1-xMnxS (x = 6.25 %; 25 %) supercells and atom relaxation and optimization of the crystal structure were carried out. Electronic band structure and density of states were calculated, the total energy has been defined in antiferromagnetic (AFM) and ferromagnetic (FM) phases. Our calculations show that the band gap increases with the increase in Mn ion concentration. It has been established that Cd or S vacancy in the crystal structure leads to the change of band gap, Fermi level shifts towards the valence or conduction band.

Effects of Morphology on the Electronic Properties of Hydrogenated Silicon Carbide Nanowires

2009 ◽  
Vol 5 ◽  
pp. 161-167 ◽  
Author(s):  
A. Miranda ◽  
J.L. Cuevas ◽  
A.E. Ramos ◽  
Miguel Cruz-Irisson
Keyword(s):  
Silicon Carbide ◽  
Band Structure ◽  
Band Gap ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Thickness Variation ◽  
Hydrogen Atoms ◽  
Electronic Density ◽  
Electronic Band ◽  
Sic Nanowires

The effects on the electronic band structure of hydrogenated cubic silicon carbide (-SiC) nanowires of changes in the diameter and morphology are studied using a semiempirical sp3s* tight-binding approach applied to a supercell model. The results of the calculation of the electronic band structure and electronic density of states obtained are compared with those calculated by density functional theory within local density approximation only for the bulk of -SiC. As boundary conditions, we passivated all the Si and C dangling bonds with hydrogen atoms. The results show that although surface morphology modifies the band gap, the change is more systematic with the thickness variation. The energy band gap increases with decreasing diameter in all cases because of quantum confinement, but the scaling is dependent on the morphology (cross-section) of the -SiC nanowires. Finally, the calculations show a consistent asymptotical behavior to the crystalline limit when the width of the wires enlarges.

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

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