Comparative DFT-D studies on structural and absorption properties of crystalline 3,3′-dinitroamino-4,4′-azoxyfurazan, 3,3′-dinitro-4,4′-azoxyfurazan, and 3,4-bis(3-nitrofurazan-4-yl)furoxan under high pressures

2015 ◽  
Vol 93 (11) ◽  
pp. 1191-1198
Author(s):  
Dong Xiang ◽  
Qiong Wu ◽  
Zhichao Liu ◽  
Weihua Zhu ◽  
Heming Xiao
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
High Pressures ◽  
Hydrostatic Compression ◽  
Band Gaps ◽  
The Other ◽  
Ambient Conditions ◽  
Absorption Properties ◽  
Functional Theory ◽  
Adsorption Activity

The structural, electronic, and absorption properties of crystalline 3,3′-dinitroamino-4,4′-azoxyfurazan (DNOAAF), 3,3′-dinitro-4,4′-azoxyfurazan (DNOAF), and 3,4-bis(3-nitrofurazan-4-yl)furoxan (BNTF) under hydrostatic compression of 0–190 GPa have been comparatively studied using density functional theory with dispersion corrections. Their crystal structures were relaxed using three types of vdW corrections such as the PBE-G06, PBE-TS, and PW91-OBS functionals at ambient conditions. The results indicate that PBE-G06 is the best functional for studying them. The compression ratios show that DNOAAF is stiffer than the other two at high pressures. An analysis of the band gaps and density of states indicates that they become more and more sensitive under compression. In the range of 0–120 GPa, BNTF is the most unstable. However, in the range of 120–190 GPa, DNOAF becomes the more unstable. The three crystals have higher optical activity at high pressures, and moreover, applied pressures change their optical adsorption activity order.

Structural transformation and electronic properties of 2-Methyl-2H-naphtho[1,8-de]triazine under hydrostatic compression

2020 ◽  
Vol 31 (09) ◽  
pp. 2050133
Author(s):  
Limin Chen ◽  
Yanbin Zhang ◽  
Kun Zhang ◽  
Xin Huang ◽  
Jun Li ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectrum ◽  
Density Functional ◽  
Structural Transformations ◽  
Hydrostatic Compression ◽  
Absorption Properties ◽  
Functional Theory ◽  
Lattice Constants ◽  
Specific Analysis ◽  
Crystal Density

In this work, the structural, electronic and absorption properties of 2-methyl-2H-naphtho-[1,8-de]triazine in the pressure ranges of 0–250[Formula: see text]GPa are studied in detail (hereinafter referred to as 2-methyl crystal). Density functional theory (DFT) is used to calculate the lattice constants, bond lengths and bond angles of 2-methyl under different pressures. The results show that the crystals undergo complex transformations under compression, and the major structural transformations occur at pressures of 90[Formula: see text]GPa and 210[Formula: see text]GPa with repeated formations and disconnections. In addition, the [Formula: see text]- and [Formula: see text]-directions of the 2-methyl are stiffer than the [Formula: see text]-direction, which indicates that the compressibility of the crystal is anisotropic. From the specific analysis of the bandgaps of 2-methyl, we can know that the crystal is converted from semiconductor to metal at 90[Formula: see text]GPa. The absorption spectrum of the crystal also indicates that 2-methyl has a relatively high optical activity with the increasing pressure.

DFT study of the structural transformations and absorption properties of crystalline 2,6-dimethyl-4-(diphenylmethylene)-2,5-cyclohexadienone under hydrostatic compression

2017 ◽  
Vol 28 (02) ◽  
pp. 1750027 ◽  
Author(s):  
Limin Chen ◽  
Henan Fang ◽  
Qiyun Xie
Keyword(s):  
Density Functional Theory ◽  
Phase Transformation ◽  
Density Functional ◽  
Pressure Range ◽  
Structural Instability ◽  
Structural Transformations ◽  
Hydrostatic Compression ◽  
Absorption Properties ◽  
Functional Theory ◽  
Lattice Constants

In this work, a detailed study of the structural, electronic and absorption properties of crystalline 2,6-dimethyl-4-(diphenylmethylene)-2,5-cyclohexadienone with [Formula: see text] form ([Formula: see text]-DDCD) in the pressure range of 0–250[Formula: see text]GPa is performed by density-functional theory (DFT) calculations. The particular analysis of the variation tendencies of the lattice constants, bond lengths and bond angles under different pressures shows that there occur complex transformations in [Formula: see text]-DDCD under compression. In addition, it can be see that the [Formula: see text]-direction is much stiffer than the [Formula: see text]- and [Formula: see text]-axes in the structure of [Formula: see text]-DDCD, suggesting the compressible crystal of [Formula: see text]-DDCD has anisotropy. Then, by analyzing the bandgap and density of states (DOS) of [Formula: see text]-DDCD, it is found that the crystal undergoes a phase transformation from semiconductor to metal at 90[Formula: see text]GPa and it becomes more sensitive under compression. Besides, in the pressure range 110–170[Formula: see text]GPa, repeated transformations between metal and semiconductor occur four times, suggesting the structural instability of [Formula: see text]-DDCD in this pressure range. Finally, the relatively high optical activity with the pressure increases of [Formula: see text]-DDCD is seen from the absorption spectra, and two obvious structural transformations are also observed at 130[Formula: see text]GPa and 140[Formula: see text]GPa, respectively.

scholarly journals Computational Study of the Electron Spectra of Vapor-Phase Indole and Four Azaindoles

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1947
Author(s):  
Delano P. Chong
Keyword(s):  
Density Functional Theory ◽  
Vapor Phase ◽  
Density Functional ◽  
Computational Study ◽  
Geometry Optimization ◽  
The Other ◽  
Functional Theory ◽  
Electron Spectra

After geometry optimization, the electron spectra of indole and four azaindoles are calculated by density functional theory. Available experimental photoemission and excitation data for indole and 7-azaindole are used to compare with the theoretical values. The results for the other azaindoles are presented as predictions to help the interpretation of experimental spectra when they become available.

scholarly journals Predicting the new carbon nanocages, fullerynes: a DFT study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Qasemnazhand ◽  
Farhad Khoeini ◽  
Farah Marsusi
Keyword(s):  
Density Functional Theory ◽  
Lithium Ion Batteries ◽  
Density Functional ◽  
Lithium Ion ◽  
The Other ◽  
Electron Affinities ◽  
Chemical Formula ◽  
Functional Theory ◽  
Triple Bonds ◽  
Structural And Electronic Properties

AbstractIn this study, based on density functional theory, we propose a new branch of pseudo-fullerenes which contain triple bonds with sp hybridization. We call these new nanostructures fullerynes, according to IUPAC. We present four samples with the chemical formula of C4nHn, and the structures derived from fulleranes. We compare the structural and electronic properties of these structures with those of two common fullerenes and fulleranes systems. The calculated electron affinities of the sampled fullerynes are negative, and much smaller than those of fullerenes, so they should be chemically more stable than fullerenes. Although fulleranes also exhibit higher chemical stability than fullerynes, but pentagon or hexagon of the fullerane structures cannot pass ions and molecules. Applications of fullerynes can be included in the storage of ions and gases at the nanoscale. On the other hand, they can also be used as cathode/anode electrodes in lithium-ion batteries.

scholarly journals Electronic Structure and Optical Properties of Co and Fe Doped ZnO

2016 ◽  
Vol 43 ◽  
pp. 23-28 ◽  
Author(s):  
Chun Ping Li ◽  
Ge Gao ◽  
Xin Chen
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Band Gaps ◽  
First Principle ◽  
Functional Theory ◽  
Doped Zno ◽  
Pseudo Potential ◽  
Co Doped

First-principle ultrasoft pseudo potential approach of the plane wave based on density functional theory (DFT) has been used for studying the electronic characterization and optical properties of ZnO and Fe, Co doped ZnO. The results show that the doping impurities change the lattice parameters a little, but bring more changes in the electronic structures. The band gaps are broadened by doping, and the Fermi level accesses to the conduction band which will lead the system to show the character of metallic properties. The dielectric function and absorption peaks are identified and the changes compared to pure ZnO are analyzed in detail.

Density functional theory study on the structural, reactivity, and electronic properties of all mono-, di-, tri-, tetra-, and penta-fluoroanilines as monomers for conducting polymers

2012 ◽  
Vol 90 (10) ◽  
pp. 902-914 ◽  
Author(s):  
Hossein Shirani Il Beigi
Keyword(s):  
Density Functional Theory ◽  
Conducting Polymers ◽  
Structural Properties ◽  
Density Functional ◽  
Dipole Moments ◽  
Radical Cations ◽  
The Other ◽  
Functional Theory ◽  
Density Distributions ◽  
Electric Polarizabilities

Electrical and structural properties of mono-, di-, tri-, tetra-, and penta-fluoroanilines as candidate monomers for new conducting polymers have been investigated using hybrid density functional theory (B3LYP/6–311+G**) based methods. The effects of the number and position of the fluorine atoms on the electrical and structural properties of fluoroanilines and their radical cations have also been investigated. The values of the vibrational frequencies, charge and spin-density distributions, ionization potentials, dipole moments, electric polarizabilities, HOMO-LUMO gaps, and the NICS values of these compounds have been calculated and analyzed as well. The results showed that the double bonds in 2-fluoroaniline and 2,5-difluoroaniline are more delocalized compared with other fluoroanilines; therefore, these molecules have the most aptitude for the electropolymerization reactions. The frequency analysis showed that the electrochemical stability of 2-fluoroaniline is greater than the other fluoroanilines. Also, this molecule possesses the largest NICS value compared to the other fluoroanilines. Consequently, 2-fluoroaniline has the largest ring current and the highest conductivity among all other monomers. Based on the results obtained, 2-fluoroaniline and 2,5-difluoroaniline are the best candidate monomers among all fluoroanilines for the synthesis of corresponding conducting polymers.

Exploring the Photovoltaic Properties of Metal Bipyridine Complexes (Metal = Fe, Zn, Cr, and Ru) by Density Functional Theory

2018 ◽  
Vol 73 (4) ◽  
pp. 337-344 ◽  
Author(s):  
Ahmad Irfan ◽  
Ghulam Abbas
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Photovoltaic Performance ◽  
Open Circuit ◽  
Band Alignment ◽  
Structure Property ◽  
Ambient Conditions ◽  
Photovoltaic Properties ◽  
Functional Theory ◽  
Solar Cell Performance

AbstractThe synthesis and characterisation of mononuclear Fe complexes were carried out by using bipyridine (Compound 1) at ambient conditions. Additionally, three more derivatives were designed by substituting the central Fe metal with Zn, Cr, and Ru (Compound 2, Compound 3, and Compound 4), respectively. The ground state geometry calculations were carried out by using density functional theory (DFT) at B3LYP/6-31G** (LANL2DZ) level of theory. We shed light on the frontier molecular orbitals, electronic properties, photovoltaic parameters, and structure–property relationship. The open-circuit voltage is a promising parameter that considerably affects the photovoltaic performance; thus, we have estimated its value by considering the complexes as donors whereas TiO2 and/or Si were used as acceptors. The solar cell performance behaviour was also studied by shedding light on the band alignment and energy level offset.

scholarly journals Ab initio study of elastic anisotropies and thermal conductivities of rhenium diborides in different crystal structures

RSC Advances ◽  
2020 ◽  
Vol 10 (61) ◽  
pp. 37142-37152
Author(s):  
Yi X. Wang ◽  
Ying Y. Liu ◽  
Zheng X. Yan ◽  
W. Liu ◽  
Jian B. Gu
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Crystal Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Ab Initio Study ◽  
Ambient Conditions ◽  
Functional Theory ◽  
Thermal Conductivities

The phase stabilities, elastic anisotropies, and thermal conductivities of ReB2 diborides under ambient conditions have been investigated by using density functional theory calculations.

scholarly journals Effect of BN nanodots on the electronic properties of α- and β-graphyne sheets: a density functional theory study

2019 ◽  
Vol 13 (4) ◽  
pp. 357-364
Author(s):  
R. Majidi ◽  
H. Eftekhari ◽  
H. Bayat ◽  
Kh. Rahmani ◽  
A. M. Khairogli
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Density Functional ◽  
Band Gaps ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Nanoelectronic Devices ◽  
Hexagonal Shape ◽  
Structural And Electronic Properties ◽  
Cohesive Energies

Abstract The effect of BN nanodots with hexagonal shape on the electronic properties of α- and β-graphyne sheets is investigated. The structural and electronic properties of α- and β-graphyne sheets doped with BN nanodots are studied by using density functional theory. The cohesive energies of the systems indicate all considered structures are thermally stable. It is found that hexagonal BN nanodots can effectively open the band gap in α- and β-graphyne sheets. It means BN nanodots change α- and β-graphyne sheets from semimetal to semiconductor. The BN nanodots with different sizes are considered. It is found that band gaps of the studied α- and β-graphyne sheets doped with BN nanodots increase with the increase in the size of BN nanodots. Hence, α- and β-graphyne sheets doped with BN nanodots are promising materials for use in nanoelectronic devices based on semiconductors.

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