scholarly journals Effect of Beryllium and Magnesium Doped Stanene Single Layer on Structural and Electronic Properties Using Density Functional Theory as Implemented in Quantum ESPRESSO

2021 ◽  
Author(s):  
Alhassan Shuaibu ◽  
Yakubu Tanko ◽  
Zainab Abdurrahman ◽  
Abdullahi Lawal ◽  
Maharaz Nasir
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Fermi Level ◽  
Band Gap ◽  
Density Functional ◽  
Energy Gap ◽  
Single Layer ◽  
Quantum Spin ◽  
Band Edge ◽  
Functional Theory

Stanene is a quantum spin hall insulator and a favourable material for electronic and optoelectronic devices. Density functional theory (DFT) calculations are performed to study the band gap opening in stanene by investigating the effect of beryllium and magnesium doped stanene single layer to study the electronic and structural properties in stanene. The electronic band energy of pure stanene without spin orbit coupling (SOC) appear to show no energy gap at the Fermi level showing that stanene is a gapless material with Dirac cones at the K point and the band gap opens by a gap of 0.08 eV is opened at the K point. The electronic structure of Be and Mg doped stanene shows that the Fermi level is shifted towards the valance band edge when compared to pure stanene. We have considered 6.25, 12.5, 18.75 and 25% of both Be and mg doping. The electronic structure of Be doped stanene show that the Fermi level is shifted towards the valance band edge when compared to pure stanene. The Dirac point of stanene locates at Γ shifted by 0.38 and 0.51eV for 6.25 and 12.5 %, an energy band gap of 0.27 and 0.50 eV were obtained above the Fermi level for 6.25 and 12.5% respectively. In the case of Mg, the bandgap remains slightly above the Fermi-level and amounts to 0.34 eV for 6.25 % and 0.43eV for 12.5 %, in the case of 18.75 and 25 % the Dirac cone disappear completely, an energy gap of 0.28 eV and 0.60 eV were obtained above the Fermi level for 6.25 and 12.5% respectively, our findings show that the band gap of stanene open at 12.5% doping concentration of both Be and Mg impurities. These obtained band-gap value seem to be sufficient for use of alkaline earth metal doped stanene in optoelectronic and such applications where stanene is incapacitate for its use to switch on/off devices.

scholarly journals Electronic structure of complexes of oligomers of 3,4-ethylene-dietoxythiophene with polystyrlesulphonic acid

Surface ◽  
2021 ◽  
Vol 13(28) ◽  
pp. 84-93
Author(s):  
M. I. Terebinska ◽  
O. I. Tkachuk ◽  
A. M. Datsyuk ◽  
O. V. Filonenko ◽  
V. V. Lobanov
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Charge Distribution ◽  
Electronic Structures ◽  
Density Functional ◽  
Spiral Structure ◽  
Energy Gap ◽  
Conductive Polymer ◽  
Functional Theory ◽  
Method Of Density Functional

By the method of density functional theory (B3LYP, 6-31G **) the electronic structures of poly 3,4-ethylenedioxythiophene containing 12 links in charge states 0, +1, +2, +3 and +4 were calculated. It is shown that the oligomer of 12 units is sufficient to reflect the properties of the conductive polymer. To estimate the probability of electron density movement along the polymer chain, the width of the energy gap between NOMO and LUMO was calculated. It is shown that the molecules of oligomers EDOT and SS do not remain parallel to each other after polymerization, but rather, with increasing chain length, the latter gradually bends around the anionic unit SS; the charge distribution in the EDOT and SS oligomer complexes indicates the presence of two separated polarons at the two ends of the chain, and the asymmetry in the charge distribution also implies the presence of a curved spiral structure of the formed complex.

Graphene sheet with periodic vacancy: A first principles study

2021 ◽  
Author(s):  
Deepti Maikhuri ◽  
Jaiparkash Jaiparkash ◽  
Haider Abbas
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Electronic Structure ◽  
Band Gap ◽  
Graphene Sheet ◽  
First Principles ◽  
Density Functional ◽  
Computational Analysis ◽  
Functional Theory ◽  
First Principles Study

Abstract We present a comprehensive first-principles study of the electronic structure of graphene sheet with periodic vacancy. We report the structural, electronic, and magnetic properties of the graphene sheet with periodic vacancy that possess 48 C & 28 H atoms. Computational analysis based on density functional theory predicts that the periodic vacancy can modulate the properties of graphene sheet. Results show that periodic vacancies lead to the manipulation of band gap & could be utilized to tailor the electronic properties of the sheet. Also, it is found that, the graphene sheet with periodic vacancy is non-magnetic in nature.

Theoretical investigation of energy gap bowing in CdSxSe1−x alloy quantum dots

2017 ◽  
Vol 19 (22) ◽  
pp. 14495-14502
Author(s):  
Laxman Tatikondewar ◽  
Anjali Kshirsagar
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
Electronic Structure ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Energy Gap ◽  
Electronic Structure Calculations ◽  
Functional Theory ◽  
Alloy Quantum Dots ◽  
Structure Calculations

To investigate energy gap bowing in homogeneously alloyed CdSxSe1−x quantum dots (QDs) and to understand whether it is different from bulk, we perform density functional theory based electronic structure calculations for spherical QDs of different compositions x (0 ≤ x ≤ 1) and of varying sizes (2.2 to 4.6 nm).

scholarly journals Strain and electric field tunable electronic structure of buckled bismuthene

RSC Advances ◽  
2017 ◽  
Vol 7 (63) ◽  
pp. 39546-39555 ◽  
Author(s):  
Ming-Yang Liu ◽  
Yang Huang ◽  
Qing-Yuan Chen ◽  
Ze-Yu Li ◽  
Chao Cao ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Electric Field ◽  
First Principles ◽  
Density Functional ◽  
Single Layer ◽  
Density Functional Theory Calculations ◽  
Two Dimensional ◽  
Functional Theory

Based on first-principles density functional theory calculations, we systemically study the properties of two-dimensional buckled single-layer bismuth (b-bismuthene).

The Electronic Structure of Ga-Doped Hydrogen-Passivated Germanene: First Principle Study

2020 ◽  
Vol 833 ◽  
pp. 157-161
Author(s):  
Mauludi Ariesto Pamungkas ◽  
Husain ◽  
Achmad Kafi Shobirin ◽  
Tri Sugiono ◽  
Masruroh Masruroh
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Band Gap ◽  
Density Functional ◽  
Dft Calculation ◽  
First Principle ◽  
Hydrogen Passivation ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Hydrogenated Graphene

Germanene, which has the same structure as graphene, is an exciting novel 2D functionalized material that controls its band gap using functionalization. The effects of the Ga atom and hydrogen atoms on the structure of Ga-doped H-passivated germanene were investigated with a density functional theory (DFT) calculation. H-passivated germanene has a direct gap of 2.10 eV. Opening the band gap in the H-passivated germanene is due to transition from sp2 to sp3 orbital. Adsorption of the Ga adatom on H-site decrease the band gap to 1.38 eV. No interaction between Ga atoms and Hydrogen atoms was observed. Hence, their effects on the band structure of hydrogenated graphene were independent of each other. Our results suggest that hydrogen passivation combined with adsorption of the Ga adatoms could effectively control the band gap of germanene.

scholarly journals Electron Self-trapping in Ge2 Se3 and its Role in Ag and Sn Incorporation

2012 ◽  
Vol 1431 ◽  
Author(s):  
Arthur H. Edwards ◽  
Kristy A. Campell ◽  
Andrew C. Pineda
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Dft Calculations ◽  
Fermi Level ◽  
Density Functional ◽  
Functional Theory ◽  
Periodic Model ◽  
Self Trapping ◽  
Formation Energies

ABSTRACTWe present a set of density functional theory (DFT) calculations on the electronic structure of Ag and Sn in Ge2 Se3 in a periodic model. We show that electron self-trapping is a persistent feature in the presence of many defects. Ag and Sn autoionize upon entering Ge2 Se3 becoming Ag+ and Sn2+ , respectively, and the freed electrons self trap at the lowest energy site. Both Ag and Sn can substitute for Ge, and we present formation energies as a function of Fermi level that show that Sn can substantially alter the incorporation of Ag into the Ge2Se3 network.

scholarly journals A High-Throughput Study of the Electronic Structure and Physical Properties of Short-Period (GaAs)m(AlAs)n (m, n ≤ 10) Superlattices Based on Density Functional Theory Calculations

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 709 ◽  
Author(s):  
Qing-Lu Liu ◽  
Zong-Yan Zhao ◽  
Jian-Hong Yi ◽  
Zi-Yang Zhang
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Physical Properties ◽  
Band Gap ◽  
High Throughput ◽  
Density Functional ◽  
Functional Materials ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
High Throughput Study

As important functional materials, the electronic structure and physical properties of (GaAs)m(AlAs)n superlattices (SLs) have been extensively studied. However, due to limitations of computational methods and computational resources, it is sometimes difficult to thoroughly understand how and why the modification of their structural parameters affects their electronic structure and physical properties. In this article, a high-throughput study based on density functional theory calculations has been carried out to obtain detailed information and to further provide the underlying intrinsic mechanisms. The band gap variations of (GaAs)m(AlAs)n superlattices have been systematically investigated and summarized. They are very consistent with the available reported experimental measurements. Furthermore, the direct-to-indirect-gap transition of (GaAs)m(AlAs)n superlattices has been predicted and explained. For certain thicknesses of the GaAs well (m), the band gap value of (GaAs)m(AlAs)n SLs exponentially increases (increasing n), while for certain thicknesses of the AlAs barrier (n), the band gap value of (GaAs)m(AlAs)n SLs exponentially decreases (increasing m). In both cases, the band gap values converge to certain values. Furthermore, owing to the energy eigenvalues at different k-points showing different variation trends, (GaAs)m(AlAs)n SLs transform from a Γ-Γ direct band gap to Γ-M indirect band gap when the AlAs barrier is thick enough. The intrinsic reason for these variations is that the contributions and positions of the electronic states of the GaAs well and the AlAs barrier change under altered thickness conditions. Moreover, we have found that the binding energy can be used as a detector to estimate the band gap value in the design of (GaAs)m(AlAs)n devices. Our findings are useful for the design of novel (GaAs)m(AlAs)n superlattices-based optoelectronic devices.

scholarly journals A Study of the electronic structure of CdS Nanocrystals using density functional theory

2019 ◽  
Vol 12 (24) ◽  
pp. 25-32
Author(s):  
Thekra Kasim
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Lattice Constant ◽  
Density Functional ◽  
Energy Gap ◽  
Orbital Energy ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Unoccupied Orbital ◽  
Occupied Orbital

Density Functional Theory at the generalized-gradient approximation level coupled with large unit cell method is used to simulate the electronic structure of (II-VI) zinc-blende cadmium sulfide nanocrystals that have dimensions 2-2.5 nm. The calculated properties include lattice constant, conduction and valence bands width, energy of the highest occupied orbital, energy of the lowest unoccupied orbital, energy gap, density of states etc. Results show that lattice constant and energy gap converge to definite values. However, highest occupied orbital, lowest unoccupied orbital fluctuates indefinitely depending on the shape of the nanocrystal.

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