scholarly journals First Principles Study of Electronic and Optical Properties of Pristine and X (Cu, Ag And Au) Doped BiOBr

2018 ◽  
Vol 22 (2) ◽  
pp. 63-69 ◽  
Author(s):  
Samir Paudel ◽  
Puspa Raj Adhikari ◽  
Om Prakash Upadhyay ◽  
Gopi Chandra Kaphle ◽  
Anurag Srivastava
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Ab Initio Approach ◽  
Indirect Band Gap ◽  
Standard Density

The electronic structures and optical properties of pristine BiOBr and Cu, Ag and Au doped BiOBr have been analyzed by using a standard density functional theory based ab-initio approach employing generalized gradient approximation through revised Perdew Burke Ernzerhoff type parameterization. The calculation shows that both the doped and pristine BiOBr have indirect band gap, the band gap of the pristine BiOBr found 2.22eV, whereas band gap significantly reduced after doping Cu, Ag and Au on BiOBr. The band gap of Cu, Ag and Au doped BiOBr are 1.2eV, 0.9eV and 1.76eV respectively. The optical properties have been studied through dielectric function, both pure and doped BiOBr shows anisotropic nature. Journal of Institute of Science and TechnologyVolume 22, Issue 2, January 2018, page: 63-69 

scholarly journals Stable GaSe-Like Phosphorus Carbide Monolayer with Tunable Electronic and Optical Properties from Ab Initio Calculations

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1937 ◽  
Author(s):  
Xiaolin Cai ◽  
Zhili Zhu ◽  
Weiyang Yu ◽  
Chunyao Niu ◽  
Jianjun Wang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Electronic Structures ◽  
Density Functional ◽  
Promising Candidate ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Direct Band Gap ◽  
Direct Band ◽  
Indirect Band Gap

On the basis of density functional theory (DFT) calculations, we propose a stable two-dimensional (2D) monolayer phosphorus carbide (PC) with a GaSe-like structure, which has intriguing electronic and optical properties. Our calculated results show that this 2D monolayer structure is more stable than the other allotropes predicted by Tománek et al. [Nano Lett., 2016, 16, 3247–3252]. More importantly, this structure exhibits superb optical absorption, which can be mainly attributed to its direct band gap of 2.65 eV. The band edge alignments indicate that the 2D PC monolayer structure can be a promising candidate for photocatalytic water splitting. Furthermore, we found that strain is an effective method used to tune the electronic structures varying from direct to indirect band-gap semiconductor or even to metal. In addition, the introduction of one carbon vacancy in such a 2D PC structure can induce a magnetic moment of 1.22 µB. Our findings add a new member to the 2D material family and provide a promising candidate for optoelectronic devices in the future.

Increased Malleability in Tetragonal Zrx Ti1−x O2 Ternary Alloys: First-Principles Approach

2017 ◽  
Vol 72 (6) ◽  
pp. 567-572
Author(s):  
F. Ayedun ◽  
P.O. Adebambo ◽  
B.I. Adetunji ◽  
V.C. Ozebo ◽  
J.A. Oguntuase ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Ternary Alloys ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Direct Band ◽  
Indirect Band Gap ◽  
Projector Augmented Wave ◽  
Alloying Effects

AbstractTetragonal phase of ZrxTi1−xO2ternary alloys is studied using generalized gradient approximation (GGA) projector augmented wave-based density functional theory (DFT). The calculations are used to characterize alloying effects of Zr substituting Ti in tutile TiO2. Band gap calculations show a direct band gap atx=0, while at other concentrations, an indirect band gap is observed. Electronic structure analysis shows that Zr alloying is capable of lowering the band gap transition of ZrxTi1−xO2atx=1 by the presence of an impurity state of transition metal Zr 5S2on the upper edge of the valence band. The addition of Zr also results in the corresponding increment in lattice constant with the material becoming more ductile and malleable.

Electronic Structure, Effective Masses and Optical Properties of Monoclinic HfO2 from First-Principles Calculations

2011 ◽  
Vol 216 ◽  
pp. 341-344 ◽  
Author(s):  
Qi Jun Liu ◽  
Zheng Tang Liu ◽  
Li Ping Feng
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Structure ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Effective Masses ◽  
Indirect Band Gap ◽  
Calculated Equilibrium

Electronic structure, effective masses and optical properties of monoclinic HfO2were studied using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT). The calculated equilibrium lattice parameters are in agreement with the previous works. From the band structure, the effective masses and optical properties are obtained. The calculated band structure shows that monoclinic HfO2has indirect band gap and all of the effective masses of electrons and holes are less than that of a free electron. The peaks position distributions of imaginary parts of the complex dielectric function have been explained according to the theory of crystal-field and molecular-orbital bonding.

scholarly journals First principles DFT calculations of the optical properties of A4BX6 group crystals

2021 ◽  
Vol 22 (1) ◽  
pp. 117-122
Author(s):  
H. Ilchuk ◽  
M. Solovyov ◽  
I. Lopatynskyi ◽  
F. Honchar ◽  
F. Tsyupko
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Energy Band ◽  
Density Functional ◽  
Near Infrared ◽  
Infrared Region ◽  
Energy Structure ◽  
Generalized Gradient ◽  
Reflection Index ◽  
Functional Theory

The results of investigating of the electron band energy structure and optical properties of A4BX6 (Tl4HgI6 and Tl4CdI6) group crystals are presented. The energy band structures of Tl4HgI6 and Tl4CdI6 crystals are calculated from the first principles within generalized gradient approximation (GGA). The band structure and reflection index were calculated using a pseudopotential method in the framework of density functional theory. Optical absorption edge in Tl4HgI6 and Tl4CdI6 is formed by direct optical transitions. The spectral dependence of the reflection index was calculated on the basis of the energy band results with using the Kramers–Kronig method. The spectra show pronounced anisotropy in E||a(b) and E||c polarizations. It was found the anomalous by large values of the birefringence (Δn > 0.18 for Tl4HgI6 and Δn > 0.03 for Tl4CdI6) in the visible and near infrared region.

Electronic structures and optical properties of IV A elements-doped 3C-SiC from density functional calculations

2018 ◽  
Vol 32 (32) ◽  
pp. 1850389 ◽  
Author(s):  
Xuefeng Lu ◽  
Tingting Zhao ◽  
Xin Guo ◽  
Meng Chen ◽  
Junqiang Ren ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Electronic Structures ◽  
Density Functional ◽  
Visible Region ◽  
First Principles Calculation ◽  
Charge Difference Density ◽  
Direct Band ◽  
Density Analysis ◽  
Indirect Band Gap

Electronic structures and optical properties of IV A elements (Ge, Sn and Pb)-doped 3C-SiC are investigated by means of the first-principles calculation. The results reveal that the structure of Ge-doped system is more stable with a lower formation energy of 1.249 eV compared with those of Sn- and Pb-doped 3C-SiC systems of 3.360 eV and 5.476 eV, respectively. Doping of the IV A elements can increase the band gap, and there is an obvious transition from an indirect band gap to a direct band gap. Furthermore, charge difference density analysis proves that the covalent order of bonding between the doping atoms and the C atoms is Ge–C [Formula: see text] Sn–C [Formula: see text] Pb–C, which is fully verified by population values. Due to the lower static dielectric constant, the service life of 3C-SiC dramatically improved in production practice. Moreover, the lower reflectivity and absorption peak in the visible region, implying its wide application foreground in photoelectric devices.

The Electronic and Structural Properties of 3C-SiC: A First-Principles Study

2014 ◽  
Vol 971-973 ◽  
pp. 208-212 ◽  
Author(s):  
Ying Gao ◽  
Fu Chun Zhang ◽  
Wei Hu Zhang
Keyword(s):  
Band Gap ◽  
Valence Band ◽  
Conduction Band ◽  
First Principles ◽  
Density Functional ◽  
Energy Splitting ◽  
Functional Theory ◽  
Structure Density ◽  
Indirect Band Gap ◽  
Electronic And Structural Properties

We investigate geometric structure, electronic structure and ground properties of 3C-SiC as obtained form first-principles calculations based on density functional theory with the LDA, GGA, B3LYP and HSE06 method. After comparative analysis of the total energy, band structure, density of states and the bulk modulus, we found that 3C-SiC was an indirect band gap semiconductor, the top of valence band was located at Γ point, and the bottom of conduction band was located at X point. The indirect band gap of 3C-SiC calculated by LDA, GGA, B3LYP and HSE06 was 1.34 eV, 1.44 eV, 2.88 eV and 2.26 eV, respectively. Especially for B3LYP and HSE06 methods which clearly calculated the energy splitting and the energy dispersion of both the top of valence band and the bottom of conduction band was in well agreement with the experimental data. These results will provide theoretical basis for the design and application of SiC materials.

A DFT study of pressure-induced phase transitions, structural and electronic properties of Cu2ZnSnS4

2016 ◽  
Vol 30 (16) ◽  
pp. 1650176 ◽  
Author(s):  
Yifen Zhao ◽  
Decong Li ◽  
Zuming Liu
Keyword(s):  
Phase Transitions ◽  
Band Gap ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Theoretical Work ◽  
Functional Theory ◽  
Phase Transition Pressure ◽  
Structural And Electronic Properties ◽  
Direct Band

The structural properties, phase transitions, and electronic structures of Cu2ZnSnS4 (CZTS) in the three structures have been researched using the first-principles density functional theory (DFT). The results indicate that the energies of stannite (ST) and pre-mixed Cu–Au (PMCA) CZTS are higher than those of kesterite (KS) CZTS, indicating that the KS CZTS is more stable. We found the phase transition pressure between the KS and ST structures of CZTS is about 32 GPa. Moreover, for KS- and PMCA-CZTS, there exists in the mischcrystal phase between 52 GPa and 65 GPa. The band structures show that the KS- and ST-CZTS are direct band gap semiconductors. The band gaps of three-type CZTS increase with increasing pressure, and the maximum band gap of KS and ST structures for CZTS occurs at 50 GPa. However, PMCA CZTS possesses metal property. Furthermore, the PMCA CZTS translates from metal to the indirect semiconductor with increasing pressure. The results play an important role in future experimental and theoretical work for CZTS materials.

Electronic structure and magnetic ordering in gadolinium-doped AlGaN from LSDA + U calculations

2018 ◽  
Vol 07 (03) ◽  
pp. 1850019 ◽  
Author(s):  
S. Belhachi ◽  
S. Amari ◽  
B. Bouhafs
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Magnetic Ordering ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Indirect Band Gap

We present first-principles calculations of the structural, electronic and magnetic properties of Gd-doped [Formula: see text] based on the density functional theory within [Formula: see text] schemes. It is found that Gd atom favors substituting for Al site. Compared with undoped [Formula: see text], the Gd-doped [Formula: see text] has become an indirect band gap semiconductor of reduced band gap. The magnetic moment [Formula: see text] per molecule mainly comes from Gd ion with little contribution from the Ga, Al and N atoms. It is confirmed that the ferromagnetic configuration is stable for [Formula: see text]. It is found also that there is hybridization between the forbital of the Gd atom and the [Formula: see text] orbital of the N atom.

scholarly journals Electronic and optical properties of Ba(1-x)Ca(x) TiO3 and Ba(1-x)Sr(x)TiO3

2018 ◽  
Vol 3 (1) ◽  
Author(s):  
A. Belaaraj ◽  
O. Tahiri ◽  
S. Kassou ◽  
R. El Mrabet
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Low Energy ◽  
Band Gaps ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
Densities Of States ◽  
Indirect Band Gap

The effect of Ca and Sr-doping on the structural electronic and optical properties of the cubic Ba1-xCaxTiO3 and Ba1-xSrxTiO3 (x=0.4, 0.6) mixed crystals was investigated using first-principles calculations based on density functional theory (DFT). The calculated band structures based on the optimized geometry of the cell for the solid solutions show an indirect band gap character at M-points, with low energy dispersion along height symmetry directions in the Brillouin zone. The band gaps increase with Ca and Sr concentrations. The total and partial densities of states were analyzed to examine the contribution of different orbitals to the maximum of valence band and the minimum of the conduction band. The optical properties such as reflectivity, energy loss, refractive index and extinction coefficient were studied. #DFT_calculations #band_gap #density_of_states #optical_properties

First-Principles Calculations on Pure and Ga-Doped Anatase TiO2

2010 ◽  
Vol 156-157 ◽  
pp. 1385-1388
Author(s):  
Rui Qing Xu ◽  
Lan Fang Yao ◽  
Lin Li ◽  
Shuo Wang ◽  
Lin Lin Tian ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Anatase Tio2 ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Band Gap Narrowing

First-principles calculations using the plane-wave pseudo-potential (PWPP) method based on the density functional theory (DFT) is employed to study the crystal structure, band gap, density of states of anatase TiO2 doped with gadolinium (Gd). The generalized gradient approximation (GGA) based on exchange-correlation energy optimization is employed to calculate them. The calculated results demonstrate that the mixing of gadolinium dopants induces states with original titanium 3d and oxygen 2p valence band attributes to the band gap narrowing. This can enhance the photocatalytic activity of anatase TiO2.

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