scholarly journals Density-functional calculation of static screening in two-dimensional materials: The long-wavelength dielectric function of graphene

2015 ◽  
Vol 91 (16) ◽  
Author(s):  
Thibault Sohier ◽  
Matteo Calandra ◽  
Francesco Mauri
Keyword(s):  
Dielectric Function ◽  
Density Functional ◽  
Two Dimensional ◽  
Density Functional Calculation ◽  
Long Wavelength ◽  
Two Dimensional Materials ◽  
Static Screening

scholarly journals 3D continuum phonon model for group-IV 2D materials

2017 ◽  
Vol 8 ◽  
pp. 1345-1356 ◽  
Author(s):  
Morten Willatzen ◽  
Lok C Lew Yan Voon ◽  
Appala Naidu Gandi ◽  
Udo Schwingenschlögl
Keyword(s):  
Molybdenum Disulfide ◽  
Density Functional ◽  
Three Dimensional ◽  
Functional Results ◽  
Group Iv ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Long Wavelength ◽  
Phonon Spectra ◽  
Two Dimensional Materials

A general three-dimensional continuum model of phonons in two-dimensional materials is developed. Our first-principles derivation includes full consideration of the lattice anisotropy and flexural modes perpendicular to the layers and can thus be applied to any two-dimensional material. In this paper, we use the model to not only compare the phonon spectra among the group-IV materials but also to study whether these phonons differ from those of a compound material such as molybdenum disulfide. The origin of quadratic modes is clarified. Mode coupling for both graphene and silicene is obtained, contrary to previous works. Our model allows us to predict the existence of confined optical phonon modes for the group-IV materials but not for molybdenum disulfide. A comparison of the long-wavelength modes to density-functional results is included.

scholarly journals Anomalous strain effect on the thermal conductivity of low-buckled two-dimensional silicene

2020 ◽  
Author(s):  
Bin Ding ◽  
Xiaoyan Li ◽  
Wuxing Zhou ◽  
Gang Zhang ◽  
Huajian Gao
Keyword(s):  
Thermal Conductivity ◽  
Strain Effect ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Heat Management ◽  
Anomalous Effect ◽  
Long Wavelength ◽  
Two Dimensional Materials ◽  
Dynamics Simulations ◽  
Energy Conversion Devices

Abstract The thermal conductivity of two-dimensional materials, such as graphene, typically decreases when tensile strain is applied, which softens their phonon modes. Here, we report an anomalous strain effect on the thermal conductivity of monolayer silicene, a representative low-buckled two-dimensional (LB-2D) material. ReaxFF-based molecular dynamics simulations are performed to show that biaxially stretched monolayer silicene exhibits a remarkable increase in the thermal conductivity, by as much as 10 times the freestanding value, with increasing applied strain in the range of [0, 0.1], which is attributed to increased contributions from long-wavelength phonons. A further increase in strain in the range of [0.11, 0.18] results in a plateau of the thermal conductivity in an oscillatory manner, governed by a unique dynamic bonding behavior under extreme loading. This anomalous effect reveals new physical insights into the thermal properties of LB-2D materials and may provide some guidelines for designing heat management and energy conversion devices based on such materials.

Mirror symmetry origin of Dirac cone formation in rectangular two-dimensional materials

2020 ◽  
Vol 22 (12) ◽  
pp. 6619-6625 ◽  
Author(s):  
Xuming Qin ◽  
Yi Liu ◽  
Gui Yang ◽  
Dongqiu Zhao
Keyword(s):  
Band Structure ◽  
Mirror Symmetry ◽  
Density Functional ◽  
Tight Binding ◽  
Coupling Mechanism ◽  
Two Dimensional ◽  
Dirac Cone ◽  
Two Dimensional Materials ◽  
Tight Binding Method ◽  
Cone Formation

The origin of Dirac cone band structure of 6,6,12-graphyne is revealed by a “mirror symmetry parity coupling” mechanism proposed with tight-binding method combined with density functional calculations.

Pd1/BN as a promising single atom catalyst of CO oxidation: a dispersion-corrected density functional theory study

RSC Advances ◽  
2015 ◽  
Vol 5 (103) ◽  
pp. 84381-84388 ◽  
Author(s):  
Zhansheng Lu ◽  
Peng Lv ◽  
Jie Xue ◽  
Huanhuan Wang ◽  
Yizhe Wang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Metal Atom ◽  
Density Functional ◽  
Single Atom ◽  
Two Dimensional ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Metal Atoms ◽  
Two Dimensional Materials

Single metal atom catalysts exhibit extraordinary activity in a large number of reactions, and some two-dimensional materials (such as graphene and h-BN) are found to be prominent supports to stabilize single metal atoms.

scholarly journals Unveiling giant hidden Rashba effects in two-dimensional Si2Bi2

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Seungjun Lee ◽  
Young-Kyun Kwon
Keyword(s):  
Density Functional ◽  
Physical Phenomenon ◽  
Ideal Condition ◽  
Spin Orbit Coupling ◽  
Two Dimensional ◽  
Crucial Point ◽  
Functional Theory ◽  
Model Hamiltonian ◽  
Two Dimensional Materials ◽  
Theory And Model

AbstractRecently, it has been known that the hidden Rashba (R-2) effect in two-dimensional materials gives rise to a physical phenomenon called spin-layer locking (SLL). However, not only its underlying fundamental mechanism has been unclear, but also there are only a few materials exhibiting weak SLL. Here, through the first-principles density functional theory and model Hamiltonian calculation, we reveal that the R-2 SLL can be determined by the competition between the sublayer–sublayer interaction and the spin–orbit coupling, which is related to the Rashba strength. In addition, the orbital angular momentum distribution is another crucial point to realize the strong R-2 SLL. We propose that a 2D material Si2Bi2 possesses an ideal condition for the strong R-2 SLL, whose Rashba strength is evaluated to be 2.16 eVÅ, which is the greatest value ever observed in 2D R-2 materials to the best of our knowledge. Furthermore, we reveal that the interlayer interaction in a bilayer structure ensures R-2 states spatially farther apart, implying a potential application in spintronics.

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