Density Functional Study of the Electronic, Elastic and Optical Properties of Bi2O2Te

2019 ◽  
Vol 75 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Jia-Xin Chen ◽  
Xiao-Ge Zhao ◽  
Xing-Xing Dong ◽  
Zhen-Long Lv ◽  
Hong-Ling Cui
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Density Functional Method ◽  
Uniaxial Crystal ◽  
Functional Method ◽  
Functional Study ◽  
Layered Crystal ◽  
High Electron ◽  
Covalent Interactions ◽  
Zero Frequency

AbstractLayered crystal Bi2O2Te has recently been found to have high electron mobility and excellent thermoelectric properties for technical applications; however, its other properties are not well studied yet. In this work, the electronic, elastic and optical properties of Bi2O2Te are systematically studied using the density functional method. The results indicate that Bi2O2Te is a narrow band gap semiconductor. The gap is formed by the Te 5p orbital at the top of the valence band and the Bi 6p orbital at the bottom of the conduction band. There are both ionic and covalent interactions within the Bi–O layers, and these layers are linked by the ionic Bi–Te bonds forming the crystal. Bi2O2Te is mechanically stable but anisotropic. It is easy to fracture along the c axis under shear stress. Its shear modulus is far smaller than its bulk modulus, so shape deformation is easier to occur than pure volume change. Its melting point is predicted to be 1284.0 K based on an empirical formula. The calculated refractive index at zero frequency reveals that Bi2O2Te is a negative uniaxial crystal with a birefringence of 0.51, making it a potential tuning material for optical application. The characteristics and origins of other optical properties are also discussed.

First Principles Calculations of Electronic and Optical Properties of Al1-xLaxN

2011 ◽  
Vol 393-395 ◽  
pp. 110-113
Author(s):  
Chang Peng Chen ◽  
Mei Lan Qi
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Density Functional ◽  
Density Functional Method ◽  
High Energy ◽  
Functional Method ◽  
Absorption Region ◽  
Additional Absorption ◽  
Calculation Results ◽  
La Substitution

Based on the density functional method, the electronic structures and the optical properties for Al1-xLaxN(x=0, 0.0625, 0.125, 0.1875) are comparatively investigated in detail. The calculation results indicate that La substitution of the Al sites induces effective reduction of the band gap of AlN, and the band gap being continuously reduced when increasing La doping level. With the increase of La concentration, both the imaginary part of dielectric function and the absorption spectrum show red-shift corresponding to the change of band gaps. Moreover, additional absorption peaks are observed above the absorption edge in the high-energy range which widens the absorption region.

scholarly journals Electronic and optical properties of Mn–S co-doped anatase TiO2 from first-principles calculations

2016 ◽  
Vol 34 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Guohao Wu ◽  
S.K. Zheng ◽  
Xiaobing Yan
Keyword(s):  
Optical Properties ◽  
Visible Light ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Potential Candidate ◽  
Generalized Gradient ◽  
Electronic And Optical Properties ◽  
Enhanced Absorption ◽  
Co Doped

AbstractThe electronic and optical properties of Mn–S co-doped anatase TiO2 were calculated using the plane-wave-based ultrasoft pseudopotential density functional method within its generalized gradient approximation (GGA). The calculated results show that the band gap of Mn–S co-doped TiO2 is larger than that of the pure TiO2, and two impurity bands appear in the forbidden band, one of which above the valence band plays a vital role for the improvement of the visible light catalytic activity. The Mn–S co-doped anatase TiO2 could be a potential candidate for a photo catalyst because of its enhanced absorption ability of visible light.

Optical Properties of Heterodiamond BC3 from First-Principles

2013 ◽  
Vol 749 ◽  
pp. 551-555 ◽  
Author(s):  
Lei Li ◽  
Wen Xue Li ◽  
Dong Han ◽  
She Wei Xin ◽  
Yi Yang ◽  
...  
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
First Principles Calculation ◽  
Optical Absorption Coefficient ◽  
Generalized Gradient ◽  
Exchange Correlation ◽  
Electron Deficiency

First principles calculation for optical properties of a tetragonal BC3 (t-BC3) are performed through the pseudopotential density functional method. The exchange correlation potential is treated by the Perdew-Burke-Eruzerhof form of generalized gradient approximation. The basic optical constants including the real and imaginary parts of the dielectric function, the optical absorption coefficient, the reflectivity and the energy loss function were calculate in detail by this method. The results indicate that the t-BC3 is an optical anisotropic crystal and its electron-deficiency characteristic can cause some features in low energy region.

Anion-Cation Replacement Effect on the Structural and Optoelectronic Properties of the LiMX2 (M = Al, Ga, In; X = S, Se, Te) Compounds: A First Principles Study

2018 ◽  
Vol 73 (7) ◽  
pp. 645-655 ◽  
Author(s):  
Amjad Khan ◽  
M. Sajjad ◽  
G. Murtaza ◽  
A. Laref
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Density Functional Method ◽  
Covalent Bond ◽  
Functional Method ◽  
Generalized Gradient ◽  
Lattice Constants ◽  
Crystal Unit Cell ◽  
Ionic Bonds ◽  
Structural And Optoelectronic Properties

AbstractIn the chalcopyrite (or tetragonal) phase, different physical properties of the ternary LiMX2 (M = Al, Ga, In and X = S, Se, Te) compounds are studied by the very accurate density functional method. The optimized lattice constants and the bandgaps are close to the existing experimental data. In addition, for most of the LiMX2 compounds, when the cations change from Al to In and anions from S to Te, the lattice constant and equilibrium volume for the crystal unit cell increase whereas the bulk modulus decreases. Using different generalized gradient approximations, the band structure calculations are performed. Generally, it was observed that there exists a decreasing tendency of the bandgap energies except for the LiAlSe2, LiInSe2, and LiGaTe2 compounds due to the change from Al to In as well as the change from S to Te. The bonding analysis shows that ionic bonds are present between the Li-X atoms, while a covalent bond exists between the M cations and X anions. The optical properties of the compounds are studied by calculating the real and imaginary components of the refractive index, reflectivity, optical conductivity, and birefringence. In addition, the optical properties from the calculations show that these materials are appropriate applicants to be utilized as Bragg’s reflector or applied in optoelectronic and solar cell technology.

Electronic Structure and Optical Properties of La or In Doped SnO2: First-Principles Calculations

2011 ◽  
Vol 393-395 ◽  
pp. 80-83
Author(s):  
Chang Peng Chen ◽  
Mei Lan Qi
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
First Principles Calculations ◽  
Effective Reduction ◽  
Calculation Results ◽  
Impurity Elements

Based on the density functional method, the electronic structures and the optical properties for pure and La or In doped SnO2 are comparatively investigated in detail. The calculation results indicate that both the doping of La and the doping of In induce effective reduction of the band gap of SnO2, the impurity elements form new highly localized impurity energy level at the top of the valence band near the Fermi level. The interaction between electrons changed after doping which leads to the change of electrical properties .Meanwhile, red shifts are revealed in both the imaginary part of dielectric function and the absorption spectra corresponding to the change of band gaps

VIBRATIONAL SPECTROSCOPIC INVESTIGATION AND CONFORMATIONAL ANALYSIS OF 1-PENTYLAMINE: A COMPARATIVE DENSITY FUNCTIONAL STUDY

2010 ◽  
Vol 09 (03) ◽  
pp. 667-685 ◽  
Author(s):  
ÖZGÜR ALVER ◽  
CEMAL PARLAK
Keyword(s):  
Density Functional ◽  
Density Functional Method ◽  
Absolute Error ◽  
Functional Method ◽  
Basis Set ◽  
Functional Study ◽  
Stable Form ◽  
Water Solvent ◽  
B3lyp Method ◽  
Ft Ir

The possible stable conformers of 1-pentylamine (1-pa) molecule were experimentally and theoretically studied by FT-IR and Raman spectroscopy in the region of 4000–400 cm-1. The optimized geometric structures concerning the minimum on the potential energy surface were investigated by Becke-3–Lee–Yang–Parr (B3LYP) density functional method together with 6-31G(d) basis set. Based on the energy calculations, 10 possible rotamers of 1-pa (TT, TG, GT, GT1, GG1, GG2, GG3, GG4, GG5 and GG6; T and G denote trans and gauge, respectively) were proposed. Optimized energies of the possible conformers were obtained in the gas phase and within the chloroform, carbon tetrachloride, methanol and water solvent environments all of which have different polarities. Comparison between the experimental and theoretical results based on the correlation graphics and mean absolute error calculations presented in this study indicates that density functional B3LYP method is able to provide satisfactory results for predicting vibrational wavenumbers and TT isomer is the most stable form of 1-pa molecule.

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