Tuning of electronic band gaps and optoelectronic properties of binary strontium chalcogenides by means of doping of magnesium atom(s)- a first principles based theoretical initiative with mBJ, B3LYP and WC-GGA functionals

2018 ◽  
Vol 530 ◽  
pp. 53-68 ◽  
Author(s):  
Bimal Debnath ◽  
Utpal Sarkar ◽  
Manish Debbarma ◽  
Rahul Bhattacharjee ◽  
Surya Chattopadhyaya
Keyword(s):  
First Principles ◽  
Optoelectronic Properties ◽  
Band Gaps ◽  
Magnesium Atom ◽  
Electronic Band

scholarly journals Accurate Prediction of Band Structure of FeS2: A Hard Quest of Advanced First-Principles Approaches

2021 ◽  
Vol 9 ◽  
Author(s):  
Min-Ye Zhang ◽  
Hong Jiang
Keyword(s):  
Band Structure ◽  
First Principles ◽  
High Energy ◽  
Accurate Prediction ◽  
Band Gaps ◽  
Full Potential ◽  
Band Structures ◽  
Electronic Band ◽  
Fundamental Band ◽  
Hybrid Functionals

The pyrite and marcasite polymorphs of FeS2 have attracted considerable interests for their potential applications in optoelectronic devices because of their appropriate electronic and optical properties. Controversies regarding their fundamental band gaps remain in both experimental and theoretical materials research of FeS2. In this work, we present a systematic theoretical investigation into the electronic band structures of the two polymorphs by using many-body perturbation theory with the GW approximation implemented in the full-potential linearized augmented plane waves (FP-LAPW) framework. By comparing the quasi-particle (QP) band structures computed with the conventional LAPW basis and the one extended by high-energy local orbitals (HLOs), denoted as LAPW + HLOs, we find that one-shot or partially self-consistent GW (G0W0 and GW0, respectively) on top of the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation with a converged LAPW + HLOs basis is able to remedy the artifact reported in the previous GW calculations, and leads to overall good agreement with experiment for the fundamental band gaps of the two polymorphs. Density of states calculated from G0W0@PBE with the converged LAPW + HLOs basis agrees well with the energy distribution curves from photo-electron spectroscopy for pyrite. We have also investigated the performances of several hybrid functionals, which were previously shown to be able to predict band gaps of many insulating systems with accuracy close or comparable to GW. It is shown that the hybrid functionals considered in general fail badly to describe the band structures of FeS2 polymorphs. This work indicates that accurate prediction of electronic band structure of FeS2 poses a stringent test on state-of-the-art first-principles approaches, and the G0W0 method based on semi-local approximation performs well for this difficult system if it is practiced with well-converged numerical accuracy.

scholarly journals Novel ultra-hard hexacarbon allotropes from first principles

2022 ◽  
Author(s):  
Samir F. Matar ◽  
Vladimir L. Solozhenko
Keyword(s):  
Elastic Constants ◽  
Vickers Hardness ◽  
Ground State ◽  
First Principles ◽  
Geometry Optimization ◽  
Band Gaps ◽  
Electronic Band ◽  
Carbon Allotropes ◽  
Ground State Structures ◽  
Electronic Band Structures

Novel ultra-hard hexacarbon C6 allotropes are proposed based on crystal chemistry rationale and geometry optimization onto ground state structures. Similar to diamond, the orthorhombic, tetragonal and trigonal C6 are cohesive networks of C4 tetrahedra illustrated by charge density projections exhibiting sp3-like carbon hybridization. All three allotropes are identified as mechanically (elastic constants) and dynamically (phonons) stable. The electronic band structures are characteristic of insulators with large band gaps of 4 to 5 eV, like diamond. From three different models evaluating Vickers hardness HV, all new carbon allotropes are identified as ultra-hard.

scholarly journals First Principles Study of Copper Sulfides (for Applications as Photoconductors)

2012 ◽  
Vol 730-732 ◽  
pp. 111-116 ◽  
Author(s):  
Jorge A. Ferreira ◽  
M. Helena Braga
Keyword(s):  
First Principles ◽  
Electronic Band Structure ◽  
Band Gaps ◽  
Solid Solution Series ◽  
Electronic Band ◽  
Copper Sulfides ◽  
Direct Band Gap ◽  
Photovoltaic Materials ◽  
Complete Solid Solution ◽  
Direct Band

The Tetrahedrite’s family constitutes a complete solid-solution series, and is among the most frequent complex sulfides in Nature. This kind of structure can be generically expressed by the composition, Cu12Sb4S13. We have calculated the electronic band structure of Cu12Sb4S13 and Ag6Cu6Sb4S13 (with band gaps of 1.24 and 1.20 eV, respectively) to demonstrate that different elements occupying certain sites of the crystal structure will make a difference in what concerns the conduction process in Tetrahedrites. We will use this effect and ab initio calculations to show that the electronic properties of these compounds make them promising candidates as solar cells photovoltaic materials since not only they possess a direct band gap but their energy falls within the range of energies of photovoltaics. Moreover, we can optimize these properties by doping and substituting ions furthermore. Mechanical properties were also calculated for both compounds and will be compared.

Electronic Properties of Hydrogenated Graphene-Like Materials Under Strains

2014 ◽  
Vol 1658 ◽  
Author(s):  
K. Mihara ◽  
K. Shintani
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Tensile Strain ◽  
Band Gaps ◽  
First Principles Calculation ◽  
Honeycomb Lattice ◽  
Electronic Band ◽  
Hydrogenated Graphene ◽  
Zigzag Direction ◽  
Electronic Band Structures

ABSTRACTThe electronic band structures of the hydrogenated graphene-like materials, graphane, silicane, and germanane, under tensile strains are calculated using first-principles calculation. The imposed tensile strain is in either the armchair or zigzag direction in the honeycomb lattice. It is found that the band gap of graphane gradually increases with the increase of the strain, whereas the band gaps of silicane and germanane decrease with the increase of the strain. There is little effect of the direction of the imposed strain on such strain dependences.

scholarly journals Predominance of non-adiabatic effects in zero-point renormalization of the electronic band gap

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Anna Miglio ◽  
Véronique Brousseau-Couture ◽  
Emile Godbout ◽  
Gabriel Antonius ◽  
Yang-Hao Chan ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Large Scale ◽  
Zero Point ◽  
Band Gaps ◽  
Electronic Band ◽  
Electron Phonon Interaction ◽  
Point Motion ◽  
Optical Properties Of Materials ◽  
Global Agreement

Abstract Electronic and optical properties of materials are affected by atomic motion through the electron–phonon interaction: not only band gaps change with temperature, but even at absolute zero temperature, zero-point motion causes band-gap renormalization. We present a large-scale first-principles evaluation of the zero-point renormalization of band edges beyond the adiabatic approximation. For materials with light elements, the band gap renormalization is often larger than 0.3 eV, and up to 0.7 eV. This effect cannot be ignored if accurate band gaps are sought. For infrared-active materials, global agreement with available experimental data is obtained only when non-adiabatic effects are taken into account. They even dominate zero-point renormalization for many materials, as shown by a generalized Fröhlich model that includes multiple phonon branches, anisotropic and degenerate electronic extrema, whose range of validity is established by comparison with first-principles results.

Electronic properties of monolayer molybdenum dichalcogenides under strains

2015 ◽  
Vol 1726 ◽  
Author(s):  
J. Sugimoto ◽  
K. Shintani
Keyword(s):  
First Principles ◽  
Tensile Strain ◽  
Compressive Strain ◽  
Band Gaps ◽  
First Principles Calculation ◽  
Honeycomb Lattice ◽  
Biaxial Strain ◽  
Electronic Band ◽  
Zigzag Direction ◽  
Electronic Band Structures

ABSTRACTThe electronic band structures of monolayer molybdenum dichalcogenides, MoS2, MoSe2, and MoTe2 under either uniaxial or biaxial strain are calculated using first-principles calculation with the GW method. The imposed uniaxial strain is in the zigzag direction in the honeycomb lattice whereas the imposed biaxial strain is in the zigzag and armchair directions. It is found that the band gaps of these dichalcogenides almost linearly increase with the decrease of the magnitude of compressive strain, reach their maxima at some compressive strain, and then decrease almost linearly with the increase of tensile strain. It is also found their maximum band gaps are direct bandgaps.

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