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.

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.

Effect of strain on the magnetism of Fe-doped MoTe2 monolayer

2019 ◽  
Vol 33 (25) ◽  
pp. 1950304 ◽  
Author(s):  
Murong Zhang ◽  
Xiaojun Wang ◽  
Xin Wang ◽  
Ying Wang ◽  
Mingyan Wei ◽  
...  
Keyword(s):  
Density Of States ◽  
Magnetic Moment ◽  
First Principles ◽  
Tensile Strain ◽  
Compressive Strain ◽  
First Principles Calculation ◽  
Biaxial Strain

First-principles calculation has been performed to investigate the effect of strain on the magnetic moment of Fe-doped MoTe2 monolayer. Our results show that the Fe-doped MoTe2 monolayer is semiconductor with the magnetic moment of 2.037 [Formula: see text]. By analyzing the density of states, we find that the magnetic moment is mainly contributed by the Fe atom. When the biaxial strain is applied along the layer, the results show that the magnetic moment is almost unchanged when the compressive strain is under 5% and tensile strain is under 7%. However, as the strain increases, the magnetic moment decreases to almost zero with compressive strain larger than 7%, and the magnetic moment begins to increase with the tensile strain larger than 8%, which indicates the different effects of compressive strain and tensile strain on the magnetism of Fe-doped MoTe2.

SILICON-BASED HALF-METAL: METAL-ENCAPSULATED SILICON NANOTUBE

NANO ◽  
2007 ◽  
Vol 02 (02) ◽  
pp. 109-114 ◽  
Author(s):  
J. BAI ◽  
X. C. ZENG
Keyword(s):  
First Principles ◽  
First Principles Calculation ◽  
Electronic Band ◽  
Half Metallic ◽  
Half Metal ◽  
Silicon Nanostructure ◽  
Metal Metal ◽  
Silicon Based ◽  
Electronic Band Structures ◽  
Silicon Nanotube

We performed first-principles calculation to show that a host–guest silicon nanostructure can exhibit half-metallic properties, wherein the host is a single-walled hexagonal silicon nanotube while the guest is a hybrid atomic chain of Mn and Co (encapsulated in the host nanotube). The calculated electronic band structures indicate that the Fermi level intersects only in the spin-up band, whereas the spin-down band exhibits semiconducting characteristics.

scholarly journals Strain Dependence of Energetics and Kinetics of Vacancy in Tungsten

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3375
Author(s):  
Zhong-Zhu Li ◽  
Yu-Hao Li ◽  
Qing-Yuan Ren ◽  
Fang-Fei Ma ◽  
Fang-Ya Yue ◽  
...  
Keyword(s):  
Binding Energy ◽  
First Principles ◽  
Tensile Strain ◽  
Kinetic Monte Carlo ◽  
Compressive Strain ◽  
Biaxial Strain ◽  
Poisson Effect ◽  
Vacancy Clusters ◽  
Object Kinetic Monte Carlo ◽  
Kinetic Monte Carlo Simulations

We investigate the influence of hydrostatic/biaxial strain on the formation, migration, and clustering of vacancy in tungsten (W) using a first-principles method, and show that the vacancy behaviors are strongly dependent on the strain. Both a monovacancy formation energy and a divacancy binding energy decrease with the increasing of compressive hydrostatic/biaxial strain, but increase with the increasing of tensile strain. Specifically, the binding energy of divacancy changes from negative to positive when the hydrostatic (biaxial) tensile strain is larger than 1.5% (2%). These results indicate that the compressive strain will facilitate the formation of monovacancy in W, while the tensile strain will enhance the attraction between vacancies. This can be attributed to the redistribution of electronic states of W atoms surrounding vacancy. Furthermore, although the migration energy of the monovacancy also exhibits a monotonic linear dependence on the hydrostatic strain, it shows a parabola with an opening down under the biaxial strain. Namely, the vacancy mobility will always be promoted by biaxial strain in W, almost independent of the sign of strain. Such unexpected anisotropic strain-enhanced vacancy mobility originates from the Poisson effect. On the basis of the first-principles results, the nucleation of vacancy clusters in strained W is further determined with the object kinetic Monte Carlo simulations. It is found that the formation time of tri-vacancy decrease significantly with the increasing of tensile strain, while the vacancy clusters are not observed in compressively strained W, indicating that the tensile strain can enhance the formation of voids. Our results provide a good reference for understanding the vacancy behaviors in W.

First-principles study of the stability of silicane and germanane under strain

2014 ◽  
Vol 28 (17) ◽  
pp. 1450138 ◽  
Author(s):  
T. Y. Du ◽  
J. Zhao ◽  
G. Liu ◽  
J. X. Le ◽  
B. Xu
Keyword(s):  
First Principles ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Tensile Strain ◽  
Helmholtz Free Energy ◽  
Compressive Strain ◽  
Specific Capacity ◽  
Biaxial Strain ◽  
Functional Theory ◽  
The Stability

In this paper, we investigate the structural stability of silicane and germanane under biaxial strain by employing the lattice dynamics calculations within the frame of density functional theory. Our results show that silicane and germanane become unstable even under 1% compressive strain, while maintaining stable under tensile strain. Further calculations about the thermodynamical properties of silicane and germanane show that the phonon contribution to Helmholtz free energy, entropy and specific capacity are insensitive to the tensile strain.

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.

Structures and Electronic Properties of Graphene with Vacancy Defects

2014 ◽  
Vol 1658 ◽  
Author(s):  
J. Sugimoto ◽  
K. Shintani
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
First Principles Calculation ◽  
Band Structures ◽  
Electronic Band ◽  
Vacancy Defects ◽  
Electronic Band Structures ◽  
Formation Energies

ABSTRACTThe structures and electronic properties of graphene with defects consisting of one to six atomic vacancies are investigated using first-principles calculation. All of the geometrically possible initial structures of a movacancy or a multivacancy in graphene are equilibrated. The formation energies and electronic band structures for the equilibrated defective structures are calculated. It is suggested non-zero bandgaps may be induced in graphene by introducing some types of monovacancy or multivacancy although further checks regarding supercell size are necessary to ensure the present results.

First-principles investigation of the electronic band structures and optical properties of quaternary ABaMQ4 (A = Rb, Cs; M = P, V; and Q = S) metal chalcogenides

2018 ◽  
Vol 32 (30) ◽  
pp. 1850337
Author(s):  
Shahid Ullah ◽  
Hayat Ullah ◽  
Abdullah Yar ◽  
Sikander Azam ◽  
A. Laref
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Correlation Energy ◽  
Electronic Charge ◽  
Electromagnetic Spectrum ◽  
Metal Chalcogenides ◽  
Electronic Band ◽  
Charge Densities ◽  
Electronic Band Structures

In this paper, we study the optoelectronic properties of quaternary metal chalcogenide semiconductor ABaMQ4 (A = Rb, Cs; M = P, V; and Q = S) compounds using state-of-the-art density functional theory (DFT) with TB-mBJ approximation for the treatment of exchange-correlation energy. In particular, the electronic and optical properties of the relaxed geometries of these compounds are investigated. Our first-principles ab-initio calculations show that the CsBaPS4 and RbBaPS4 compounds have direct bandgaps whereas the CsBaVS4 compound exhibits indirect bandgap nature. Importantly, the theoretically calculated values of the bandgaps of the compounds are consistent with experiment. Furthermore, our analysis of the electronic charge densities of these compounds indicates that the above quaternary chalcogenides have mixed covalent and ionic bonding characters. The effective masses of these compounds are also calculated which provide very useful information about the band structure and transport characteristics of the investigated compounds. Similarly, high absorptivity in the visible and ultraviolet regions of the electromagnetic spectrum possibly predicts and indicates the importance of these materials for potential optoelectronic applications in this range.

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