Two novel silicon phases with direct band gaps

2016 ◽  
Vol 18 (18) ◽  
pp. 12905-12913 ◽  
Author(s):  
Qingyang Fan ◽  
Changchun Chai ◽  
Qun Wei ◽  
Yintang Yang
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Density Function ◽  
Absorption Spectra ◽  
Structural Stability ◽  
Function Theory ◽  
Density Function Theory ◽  
Band Gaps ◽  
Direct Band ◽  
Optical And Mechanical Properties

Based on density function theory with the ultrasoft pseudopotential scheme, we have systematically studied the structural stability, absorption spectra, electronic, optical and mechanical properties and minimum thermal conductivity of two novel silicon phases, Cm-32 silicon and P21/m silicon.

scholarly journals Density function theory (DFT) calculated infrared absorption spectra for nitrosamines

2019 ◽  
Vol 80 (10) ◽  
pp. 1967-1974 ◽  
Author(s):  
S. Wallace ◽  
S. G. Lambrakos ◽  
L. Massa
Keyword(s):  
Density Function ◽  
Absorption Spectra ◽  
Excited States ◽  
Function Theory ◽  
Spectral Feature ◽  
Density Function Theory ◽  
Spectral Signature ◽  
Proof Of Concept ◽  
Additional Information

Abstract Absorption spectra within the infrared (IR) range of frequencies for nitrosamines in water are calculated using density function theory (DFT). Calculated in this study, are the IR spectra of C2H6N2O, C4H10N2O, C6H14N2O, C4H8N2O, C3H8N2O, and C8H18N2O. DFT calculated absorption spectra corresponding to vibration excited states of these molecules in continuous water background can be correlated with additional information obtained from laboratory measurements. The DFT software Gaussian was used for the calculations of excited states presented here. This case study provides proof of concept, viz., that such DFT calculated spectra can be used for their practical detection in environmental samples. Thus, DFT calculated spectra may be used to construct templates, for spectral-feature comparison, and thus detection of spectral-signature features associated with target materials.

Structures and Mechanical Properties of CH4, SO2, and H2S Hydrates from Density Function Theory Calculations

2017 ◽  
Vol 46 (8) ◽  
pp. 1141-1144 ◽  
Author(s):  
Xinxuan Zong ◽  
Guoling Cheng ◽  
Nianxiang Qiu ◽  
Qing Huang ◽  
Jian He ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Density Function ◽  
Function Theory ◽  
Density Function Theory

Tuning the Electronic Properties of Symetrical and Asymetrical Boron Nitride Passivated Graphene Nanoribbons: Density Function Theory

2018 ◽  
Vol 54 ◽  
pp. 35-41
Author(s):  
Mohammad Bashirpour ◽  
Ali Kefayati ◽  
Mohammadreza Kolahdouz ◽  
Hossein Aghababa
Keyword(s):  
Boron Nitride ◽  
Band Gap ◽  
Density Function ◽  
Function Theory ◽  
Graphene Nanoribbons ◽  
Graphene Nanoribbon ◽  
Density Function Theory ◽  
Band Gaps ◽  
Asymmetrical Structure ◽  
Armchair Graphene

—Density function theory (DFT) based simulation combined with non-equilibrium green function (NEGF) was used to theoretically investigate electrical properties of symmetrical and asymmetrical boron nitride (BN) passivated graphene nanoribbons. Using density function theory method, it is demonstrated that the band gap of armchair (A) graphene nanoribbon (GNR) can be widened with boron nitride passivation. five symmetrical and five asymmetrical structures were considered, for which we obtained band gaps from 0.45 eV to 2 eV for symmetrical structures and 0.3 eV to 1.5 eV for asymmetrical structures. For the same width of graphene nanoribbon, our results showed that asymmetrical structure has a smaller band gap and almost the same conductance in comparison with the symmetrical one. Finally, comparison between the asymmetrical structure and the hydrogenated armchair graphene (h-AGNR) nanoribbon showed that, hBN-AGNR exhibited a higher conductance compared to an h-AGNR for the same width of GNR.

scholarly journals Synthesis and Characterisation of Copper(II) Complexes with Tridentate NNO Functionalized Ligand: Density Function Theory Study, DNA Binding Mechanism, Optical Properties, and Biological Application

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Madhumita Hazra ◽  
Tanushree Dolai ◽  
Akhil Pandey ◽  
Subrata Kumar Dey ◽  
Animesh Patra
Keyword(s):  
Density Function ◽  
Antimicrobial Agents ◽  
Function Theory ◽  
Free Ligand ◽  
Fluorescence Emission ◽  
Building Blocks ◽  
Density Function Theory ◽  
Calf Thymus Dna ◽  
Spectroscopic Techniques ◽  
Calf Thymus

The photo physical properties of two mononuclear pentacoordinated copper(II) complexes formulated as [Cu(L)(Cl)(H2O)] (1) and [Cu(L)(Br)(H2O)] (2)HL = (1-[(3-methyl-pyridine-2-ylimino)-methyl]-naphthalen-2-ol) were synthesized and characterized by elemental, physicochemical, and spectroscopic methods. The density function theory calculations are used to investigate the electronic structures and the electronic properties of ligand and complex. The interactions of copper(II) complexes towards calf thymus DNA were examined with the help of absorption, viscosity, and fluorescence spectroscopic techniques at pH 7.40. All spectroscopy's result indicates that complexes show good binding activity to calf thymus DNA through groove binding. The optical absorption and fluorescence emission properties of microwires were characterized by fluorescence microscope. From a spectroscopic viewpoint, all compounds strongly emit green light in the solid state. The microscopy investigation suggested that microwires exhibited optical waveguide behaviour which are applicable as fluorescent nanomaterials and can be used as building blocks for miniaturized photonic devices. Antibacterial study reveals that complexes are better antimicrobial agents than free Schiff base due to bacterial cell penetration by chelation. Moreover, the antioxidant study of the ligand and complexes is evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assays, which demonstrate that the complexes are of higher antioxidant activity than free ligand.

Analysis of Ring-Opening Reaction between Bisphenol A and Epichlorohydrin by the Method of Quantum Chemical Calculating

2011 ◽  
Vol 221 ◽  
pp. 180-183 ◽  
Author(s):  
Jian Li ◽  
Xun Zhang Yu ◽  
Kai Zhang
Keyword(s):  
Bisphenol A ◽  
Density Function ◽  
Quantum Chemical ◽  
Ring Opening ◽  
Function Theory ◽  
Dft Method ◽  
Density Function Theory ◽  
Ring Opening Reaction ◽  
Calculation Results ◽  
Opening Process

The ring-opening reaction between bisphenol A and epichlorohydrin was calculated by Gaussian03. The Density Function Theory (DFT) method were employed to study the geometry structures of bisphenol A and epichlorohydrin and the product was obtained on the base of B3LYP/6-31G+ model in this paper. The transitional states (Ts1, Ts2) during the ring-opening process were found by TS method and the energy changing of the system was proved by IRC calculation. Results showed that the energy reduced by 64.37726kJ/mol during the ring-opening process. The product was confirmed to be thermodynamically stable.

exo- and endo-Complexes of Fe(0) with Carbon Allotropic Modifications on the Example of Fullerene С60: a Density Function Theory Study

2021 ◽  
Vol 91 (5) ◽  
pp. 828-834
Author(s):  
K. V. Zaitsev ◽  
A. Yu. Oprunenko ◽  
I. P. Gloriozov ◽  
M. S. Nechaev ◽  
Yu. F. Oprunenko ◽  
...  
Keyword(s):  
Density Function ◽  
Function Theory ◽  
Density Function Theory ◽  
Allotropic Modifications

Silylene Reaction with Acetylene: Elucidating the Mechanism by Theoretical Identification of a New Intermediate

2011 ◽  
Vol 36 (4) ◽  
pp. 323-328
Author(s):  
Yiling Bei ◽  
Qingyang Liu
Keyword(s):  
Kinetic Analysis ◽  
Density Function ◽  
Room Temperature ◽  
Function Theory ◽  
Reaction Pathway ◽  
Dft Method ◽  
Density Function Theory

The reaction of silylene with acetylene was observed by the density function theory (DFT) method at the 6 - 311 g (d,p) level. A new reaction pathway has been identified involving the tetra-conjugated: SiH2CH==CHH2Si:. Thermodynamic and kinetic analysis confirms the reaction to be spontaneous at room temperature. The new intermediate proposed in this work offers a resolution of the conundrum of the silylene/acetylene reaction.

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