Magnetic interactions ofCr−CrandCo−Coimpurity pairs inZnOwithin a band-gap corrected density functional approach

2008 ◽  
Vol 77 (24) ◽  
Author(s):  
Stephan Lany ◽  
Hannes Raebiger ◽  
Alex Zunger
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Functional Approach ◽  
Magnetic Interactions

scholarly journals Strain-Mediated Stability of Structures and Electronic Properties of ReS2, Janus ReSSe, and ReSe2 Monolayers

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Jia-Qi Zong ◽  
Shu-Feng Zhang ◽  
Wei-Xiao Ji ◽  
Chang-Wen Zhang ◽  
Ping Li ◽  
...  
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Electronic Materials ◽  
Bond Angle ◽  
Compressive Strain ◽  
Functional Approach ◽  
The Stability ◽  
Stability Of Structures

Monolayers of transition metal ReX2 and ReSX (X=S, Se) have been proposed as new electronic materials for nanoscale devices. In this paper, there are three structures: ReS2, Janus ReSSe, and ReSe2. Based on the first-principles theory, we analyzed the structures, electronic properties, and Fermi speed. Remarkably, we studied the stability of structures of ReS2, Janus ReSSe, and ReSe2 monolayers under biaxial tensile and compressive strain by density functional approach. It is worth noting that when the strain changes, not only the band gap changes but also the band gap properties (direct and indirect) also change. The bond gaps decrease with the increase of tensile strain and compressive strain; Moreover, when the strain is greater than 0, the bond angle decreases as the strain increases, and when the strain is less than 0, the bond angle increases as the strain increases.

Efficient Prediction of Structural and Electronic Properties of Hybrid 2D Materials Using DFT and Machine Learning

2018 ◽  
Author(s):  
Sherif Tawfik ◽  
Olexandr Isayev ◽  
Catherine Stampfl ◽  
Joseph Shapter ◽  
David Winkler ◽  
...  
Keyword(s):  
Machine Learning ◽  
Band Gap ◽  
Density Functional ◽  
2D Materials ◽  
Van Der Waals ◽  
Building Blocks ◽  
Machine Learning Techniques ◽  
Interlayer Distance ◽  
Computational Screening ◽  
Wide Range

Materials constructed from different van der Waals two-dimensional (2D) heterostructures offer a wide range of benefits, but these systems have been little studied because of their experimental and computational complextiy, and because of the very large number of possible combinations of 2D building blocks. The simulation of the interface between two different 2D materials is computationally challenging due to the lattice mismatch problem, which sometimes necessitates the creation of very large simulation cells for performing density-functional theory (DFT) calculations. Here we use a combination of DFT, linear regression and machine learning techniques in order to rapidly determine the interlayer distance between two different 2D heterostructures that are stacked in a bilayer heterostructure, as well as the band gap of the bilayer. Our work provides an excellent proof of concept by quickly and accurately predicting a structural property (the interlayer distance) and an electronic property (the band gap) for a large number of hybrid 2D materials. This work paves the way for rapid computational screening of the vast parameter space of van der Waals heterostructures to identify new hybrid materials with useful and interesting properties.

scholarly journals Electronic and optical properties of vacancy ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; and X = Cl, Br, I): a first principles study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Faizan ◽  
K. C. Bhamu ◽  
Ghulam Murtaza ◽  
Xin He ◽  
Neeraj Kulhari ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Perovskite Solar Cells ◽  
Dielectric Constants ◽  
Maximum Efficiency ◽  
Exchange Potential ◽  
Double Perovskites ◽  
Electronic And Optical Properties

AbstractThe highly successful PBE functional and the modified Becke–Johnson exchange potential were used to calculate the structural, electronic, and optical properties of the vacancy-ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; X = Cl, Br, and I) using the density functional theory, a first principles approach. The convex hull approach was used to check the thermodynamic stability of the compounds. The calculated parameters (lattice constants, band gap, and bond lengths) are in tune with the available experimental and theoretical results. The compounds, Rb2PdBr6 and Cs2PtI6, exhibit band gaps within the optimal range of 0.9–1.6 eV, required for the single-junction photovoltaic applications. The photovoltaic efficiency of the studied materials was assessed using the spectroscopic-limited-maximum-efficiency (SLME) metric as well as the optical properties. The ideal band gap, high dielectric constants, and optimum light absorption of these perovskites make them suitable for high performance single and multi-junction perovskite solar cells.

scholarly journals Structural and computational investigation of an imine-based propeller-shaped macrocyclic cage

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Sriram Srinivasa Raghvan ◽  
Suresh Madhu ◽  
Velmurugan Devadasan ◽  
Gunasekaran Krishnasamy
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Strain Tensor ◽  
Strong Interactions ◽  
Soft Condensed Matter ◽  
Functional Theory ◽  
Self Assembling ◽  
Phenyl Rings ◽  
Crystal Volume

AbstractIn this study, we present the synthesis, spectroscopic and structural characterization of self-assembling gem-dimethyl imine based molecular cage (IMC). Self-assembling macrocycles and cages have well-defined cavities and have extensive functionalities ranging from energy storage, liquid crystals, and catalysts to water splitting photo absorber. IMC has large voids i.e., 25% of the total crystal volume thus could accommodate wide substrates. The synthesized imine-based molecular cages are stabilized by coaxial π bonded networks and long-range periodic van der Waal and non-bonded contacts as observed from the crystal structure. IMC also has typical properties of soft condensed matter materials, hence theoretical prediction of stress and strain tensor along with thermophysical properties were computed on crystal system and were found to be stable. Molecular dynamics revealed IMC is stabilized by, strong interactions between the interstitial phenyl rings. Density functional theory (DFT) based physicochemical properties were evaluated and has band gap of around 2.38ev (520 nm) similar to various photocatalytic band gap materials.

scholarly journals DFT Study of the Electronic Structure of Cubic-SiC Nanopores with a C-Terminated Surface

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. Calvino ◽  
A. Trejo ◽  
M. I. Iturrios ◽  
M. C. Crisóstomo ◽  
Eliel Carvajal ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Density Functional ◽  
Surface Passivation ◽  
Phase Changes ◽  
Surface Relaxation ◽  
Oh Radicals ◽  
Functional Theory ◽  
Band Gap Engineering ◽  
Chemical Surface

A study of the dependence of the electronic structure and energetic stability on the chemical surface passivation of cubic porous silicon carbide (pSiC) was performed using density functional theory (DFT) and the supercell technique. The pores were modeled by removing atoms in the [001] direction to produce a surface chemistry composed of only carbon atoms (C-phase). Changes in the electronic states of the porous structures were studied by using different passivation schemes: one with hydrogen (H) atoms and the others gradually replacing pairs of H atoms with oxygen (O) atoms, fluorine (F) atoms, and hydroxide (OH) radicals. The results indicate that the band gap behavior of the C-phase pSiC depends on the number of passivation agents (other than H) per supercell. The band gap decreased with an increasing number of F, O, or OH radical groups. Furthermore, the influence of the passivation of the pSiC on its surface relaxation and the differences in such parameters as bond lengths, bond angles, and cell volume are compared between all surfaces. The results indicate the possibility of nanostructure band gap engineering based on SiC via surface passivation agents.

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