scholarly journals First-principle calculations for electronic structure and bonding properties in layered Na2Ti3O7

Open Physics ◽  
2011 ◽  
Vol 9 (6) ◽  
Author(s):  
Yongliang An ◽  
Zhonghua Li ◽  
Hongping Xiang ◽  
Yongjiang Huang ◽  
Jun Shen
Keyword(s):  
Electronic Structure ◽  
Electron Density ◽  
Density Functional ◽  
Exchange Property ◽  
Strong Interactions ◽  
Functional Theory ◽  
Bonding Properties ◽  
Structure And Bonding ◽  
Structure Density ◽  
The Stability

AbstractFirst-principles calculations of Na2Ti3O7 have been carried out with density-functional theory (DFT) and ultrasoft pseudopotentials. The electronic structure and bonding properties in layered Na2Ti3O7 have been studied through calculating band structure, density of states, electron density, electron density difference and Mulliken bond populations. The calculated results reveal that Na2Ti3O7 is a semiconductor with an indirect gap and exhibits both ionic and covalent characters. The stability of the (Ti3O7)2− layers is attributed to the covalent bonding of strong interactions between O 2p and Ti 3d orbitals. Furthermore, the O atoms located in the innerlayers interact more strongly with the neighboring Ti atoms than those in the interlayer regions. The ion-exchange property is due to the ionic bonding between the Na+ and (Ti3O7)2− layers, which can stabilize the interlayers of layered Na2Ti3O7 structure.

scholarly journals Influence of Copper(I) Halides on the Reactivity of Aliphatic Carbodiimides

2020 ◽  
Vol 3 (1) ◽  
pp. 20
Author(s):  
Valentina Ferraro ◽  
Marco Bortoluzzi
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
General Formula ◽  
Electron Density ◽  
Density Functional ◽  
Functional Theory ◽  
Fukui Functions ◽  
Bond Lengths ◽  
Linear Complexes ◽  
Nitrogen Bond

The influence of copper(I) halides CuX (X = Cl, Br, I) on the electronic structure of N,N′-diisopropylcarbodiimide (DICDI) and N,N′-dicyclohexylcarbodiimide (DCC) was investigated by means of computational DFT (density functional theory) methods. The coordination of the considered carbodiimides occurs by one of the nitrogen atoms, with the formation of linear complexes having a general formula of [CuX(carbodiimide)]. Besides varying the carbon–nitrogen bond lengths, the thermodynamically favourable interaction with Cu(I) reduces the electron density on the carbodiimides and alters the energies of the (NCN)-centred, unoccupied orbitals. A small dependence of these effects on the choice of the halide was observable. The computed Fukui functions suggested negligible interaction of Cu(I) with incoming nucleophiles, and the reactivity of carbodiimides was altered by coordination mainly because of the increased electrophilicity of the {NCN} fragments.

Can boron form coordination complexes with diffuse electrons? Evidence for linked solvated electron precursors

2022 ◽  
Author(s):  
Zachary Jordan ◽  
Shahriar N. Khan ◽  
Benjamin A. Jackson ◽  
Evangelos Miliordos
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Molecular System ◽  
Hydrocarbon Chain ◽  
Solvated Electron ◽  
Excitation Energies ◽  
Functional Theory ◽  
Boron Complexes ◽  
The Stability ◽  
First Time

Abstract Density functional theory and ab initio multi-reference calculations are performed to examine the stability and electronic structure of boron complexes that host diffuse electrons in their periphery. Such complexes (solvated electron precursors or SEPs) have been experimentally identified and studied theoretically for several s- and d-block metals. For the first time, we demonstrate that a p-block metalloid element can form a stable SEP when appropriate ligands are chosen. We show that three ammonia and one methyl ligands can displace two of the three boron valence electrons to a peripheral 1s-type orbital. The shell model for these outer electrons is identical to previous SEP systems (1s, 1p, 1d, 2s). Further, we preformed the first examination of a molecular system consisting of two SEPs bridged by a hydrocarbon chain. The electronic structure of these dimers is very similar to that of traditional diatomic molecules forming bonding and anti-bonding σ and π orbitals. Their ground state electronic structure resembles that of two He atoms, and our results indicate that the excitation energies are nearly independent of the chain length for four carbon atoms or longer. These findings pave the way for the development of novel materials similar to expanded metals and electrides.

Why and How the Zigzag Edge of Suspended Graphene Sheet where Deformed

2013 ◽  
Vol 829 ◽  
pp. 204-207
Author(s):  
Behrad Barakati ◽  
Ahmad Yazdani ◽  
Farhang Soheilian ◽  
Mahdi Ghazanfari
Keyword(s):  
Carbon Atom ◽  
Graphene Sheet ◽  
Electron Density ◽  
Density Functional ◽  
Zigzag Chain ◽  
Zigzag Edge ◽  
Functional Theory ◽  
Electron Density Gradient ◽  
True Edge ◽  
Structure Density

The edge of graphene plays an important role in electronic and spintronic properties of graphene. As we know in many article zigzag edge used as stable edge but this edge cannot be true edge. When the graphene sheet is cut, bonds are broken along this line and electrons that participate in bond be free, so there is electron density gradient along the edge. Because of this the carbon atoms along the edge is moved till the stable structure be established. For achieving to this specific structure, density functional theory was used via Gaussian package. The result shows hexagons on the edge are going to deform to pentagon and heptagon by change the kind of bond in this chain. In the other zigzag chain behind the edge we have movement of electron density from one carbon atom to another carbon atom by help of carbon atom that placed between them. So we suggested new edge that can be replacement by zigzag edge in calculation with more less structure energy that identify in experiment method too.

First-principle study of the electronic structure and optical property of Nb-doped anatase TiO2

2014 ◽  
Vol 28 (17) ◽  
pp. 1450091
Author(s):  
Q. Y. Hou ◽  
Q. L. Liu ◽  
C. W. Zhao ◽  
Y. Zhang
Keyword(s):  
Electronic Structure ◽  
Optical Property ◽  
Band Gap ◽  
Absorption Edge ◽  
Short Wavelength ◽  
Density Functional ◽  
Functional Theory ◽  
Long Wavelength ◽  
The Density Functional Theory ◽  
The Stability

The absorption edge shifted to long wavelength direction and short wavelength direction of two opposite experimental conclusions have been reported, when the band-gap and absorption spectra of Nb -doped anatase TiO 2 were studied. In order to solve this contradiction, the electronic structure and the optical property of Nb heavy doped anatase TiO 2 have been studied by the first-principles plane-wave ultrasoft pseudopotential method based on the density functional theory with +U method modification. The calculated results indicate that the higher the Nb -doping is, the higher the total energy is, the worse the stability is, the higher the formation energy is, the more difficult the doping is, the wider the optical band-gap is, the more obvious the absorption edge shifting to short wavelength direction is, the lower the absorptivity and the reflectivity is, which is in agreement with the experimental results. The reasonable interpretation of the contradiction has been reported in this paper, too.

Magnetic circular dichroism and density functional theory studies of electronic structure and bonding in cobalt(ii)–N-heterocyclic carbene complexes

2017 ◽  
Vol 46 (39) ◽  
pp. 13290-13299 ◽  
Author(s):  
Theresa E. Iannuzzi ◽  
Yafei Gao ◽  
Tessa M. Baker ◽  
Liang Deng ◽  
Michael L. Neidig
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Magnetic Circular Dichroism ◽  
Strong Dependence ◽  
Cross Coupling ◽  
Functional Theory ◽  
Carbene Complexes ◽  
Highly Effective ◽  
Structure And Bonding

The combination of simple cobalt salts and N-heterocyclic carbene (NHC) ligands has been highly effective in C–H functionalization, hydroarylation and cross-coupling catalysis, though displaying a strong dependence on the identity of the NHC ligand.

scholarly journals Synthesis and Structure Insights of Two Novel Broad-Spectrum Antibacterial Candidates Based on (E)-N′-[(Heteroaryl)methylene]adamantane-1-carbohydrazides

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1934
Author(s):  
Lamya H. Al-Wahaibi ◽  
Natalia Alvarez ◽  
Olivier Blacque ◽  
Nicolás Veiga ◽  
Aamal A. Al-Mutairi ◽  
...  
Keyword(s):  
Electron Density ◽  
Broad Spectrum ◽  
Light Absorption ◽  
Density Functional ◽  
Pathogenic Fungus ◽  
Thiophene Ring ◽  
Density Functional Theory Calculations ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
The Stability

Two new N′-heteroarylidene-1-carbohydrazide derivatives, namely; E-N′-[(pyridine-3-yl)methylidene]adamantane-1-carbohydrazide (1) and E-N′-[(5-nitrothiophen-2-yl)methylidene]adamantane-1-carbohydrazide (2), were produced via condensation of adamantane-1-carbohydrazide with the appropriate heterocyclic aldehyde. Both compounds were chemically and structurally characterized by 1H-NMR, 13C-NMR, infrared and UV-vis spectroscopies, and single crystal X-ray diffraction. The study was complemented with density functional theory calculations (DFT). The results show an asymmetrical charge distribution in both compounds, with the electron density accumulated around the nitrogen and oxygen atoms, leaving the positive charge surrounding the N-H and C-H bonds in the hydrazine group. Consequently, the molecules stack in an antiparallel fashion in the crystalline state, although the contribution of the polar contacts to the stability of the lattice is different for 1 (18%) and 2 (42%). This difference affects the density and symmetry of their crystal structures. Both molecules show intense UV-Vis light absorption in the range 200–350 nm (1) and 200–500 nm (2), brought about by π → π* electronic transitions. The electron density difference maps (EDDM) revealed that during light absorption, the electron density flows within the π-delocalized system, among the pyridyl/thiophene ring, the nitro group, and the N′-methyleneacetohydrazide moiety. Interestingly, compounds 1 and 2 constitute broad-spectrum antibacterial candidates, displaying potent antibacterial activity with minimal inhibitory concentration (MIC) values around 0.5–2.0 μg/mL. They also show weak or moderate antifungal activity against the yeast-like pathogenic fungus Candida albicans.

scholarly journals A combined magnetic circular dichroism and density functional theory approach for the elucidation of electronic structure and bonding in three- and four-coordinate iron(ii)–N-heterocyclic carbene complexes

2015 ◽  
Vol 6 (2) ◽  
pp. 1178-1188 ◽  
Author(s):  
Kathlyn L. Fillman ◽  
Jacob A. Przyojski ◽  
Malik H. Al-Afyouni ◽  
Zachary J. Tonzetich ◽  
Michael L. Neidig
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Circular Dichroism ◽  
Density Functional ◽  
Magnetic Circular Dichroism ◽  
Theory Approach ◽  
Functional Theory ◽  
Carbene Complexes ◽  
Structure And Bonding ◽  
Circular Dichroïsm

Studies of electronic structure and bonding in iron(ii)–NHC complexes using a combined magnetic circular dichroism and DFT approach.

First-principles study on electronic structure and optical properties of In-doped GaN

2014 ◽  
Vol 13 (08) ◽  
pp. 1450070 ◽  
Author(s):  
Xingxiang Ruan ◽  
Fuchun Zhang ◽  
Weihu Zhang
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Visible Region ◽  
Solar Spectrum ◽  
Potential Method ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structure Density

The In -doped GaN is investigated by first-principles calculations of plane wave ultra-soft pseudo-potential method based on the density functional theory (DFT). The band structure, electronic structure, density of states and optical properties are investigated. The results indicate that the band-gap becomes narrower and the absorption edge of optical properties is red-shifted with the increase in In -doped concentration. Meanwhile, the visible region has strong absorption properties, and the significant absorption peaks are observed near 3.0 eV and 6.1 eV. The other peaks correspond to the wavelength of absorption spectra from the ultraviolet portion extending to the infrared portion, which almost covers the entire solar spectrum. The studied results show that In -doped GaN can be applied as solar cell and transparent conductivity material.

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