First-principles study of stability and electronic properties of single-element 2D materials

Doklady BGUIR ◽  
2022 ◽  
Vol 19 (8) ◽  
pp. 92-98
Author(s):  
D. C. Hvazdouski
Keyword(s):  
Mechanical Properties ◽  
Ab Initio Calculations ◽  
First Principles ◽  
Low Temperatures ◽  
Software Package ◽  
Phonon Dispersion ◽  
2D Materials ◽  
Single Element ◽  
Displacement Method ◽  
Phonon Dispersion Curves

We have estimated stability of single-element 2D materials (C2, N2, Si2, P2, Ge2, As2, Sn2, Sb2, Pb2, and Bi2) by ab initio calculations. The calculations of structural and mechanical properties of 2D materials were performed using the VASP software package. The results of calculations of stiffness tensors, Young's modulus, and Poisson's ratios show that all studied single-element 2D materials are mechanically stable. Dynamic stability was investigated by calculating the phonon dispersion of the materials using the finite displacement method. Only Pb2 has imaginary modes in the phonon dispersion curves and therefore it has dynamic unstable structure at low temperatures. The analysis of the band structures indicates the presence of insulators (N2), semiconductors (P2, As2, Bi2, Sb2), semimetals, and metals among the studied group of single-element 2D materials.

AB INITIO STUDY OF PHONON DISPERSION AND ELASTIC PROPERTIES OF L12 INTERMETALLICS Ti3Al AND Y3Al

2013 ◽  
Vol 27 (30) ◽  
pp. 1350224 ◽  
Author(s):  
N. ARIKAN ◽  
M. ERSEN ◽  
H. Y. OCAK ◽  
A. İYIGÖR ◽  
A. CANDAN ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Phonon Dispersion ◽  
High Symmetry ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Phonon Dispersion Curves ◽  
Lattice Constants ◽  
Density Functional Perturbation Theory ◽  
Phonon Properties

In this paper, the structural, elastic and phonon properties of Ti 3 Al and Y 3 Al in L1 2( Cu 3 Al ) phase are studied by performing first-principles calculations within the generalized gradient approximation. The calculated lattice constants, static bulk moduli, first-order pressure derivative of bulk moduli and elastic constants for both compounds are reported. The phonon dispersion curves along several high-symmetry lines at the Brillouin zone, together with the corresponding phonon density of states, are determined using the first-principles linear-response approach of the density functional perturbation theory. Temperature variations of specific heat in the range of 0–500 K are obtained using the quasi-harmonic model.

First-Principles Calculation of Force Constants and Full Phonon Dispersions

1992 ◽  
Vol 291 ◽  
Author(s):  
Siqing Wei ◽  
M. Y. Chou
Keyword(s):  
First Principles ◽  
Phonon Dispersion ◽  
Local Density ◽  
Real Space ◽  
Force Constants ◽  
First Principles Calculation ◽  
Dynamical Matrix ◽  
Phonon Dispersion Curves ◽  
Super Cell ◽  
Silicon And Germanium

ABSTRACTWe calculated the real-space force constants and full phonon dispersion curves for elemental semiconductors (silicon and germanium) under the local-density approximation with the Hellmann-Feynman forces. The force constants are obtained through super- cell calculations for planar displacements in three different symmetry directions. From these real-space force constants the dynamical matrix for an arbitrary wave vector in the Brillouin zone can be constructed. The procedure is simple in concept and requires no complicated computer programing. It is also possible in principle to handle the anharmonic effects.

First-Principles Investigations of Structural Stability of LuN

2013 ◽  
Vol 690-693 ◽  
pp. 559-563 ◽  
Author(s):  
Xiao Cui Yang ◽  
En Jie Zhang ◽  
Hong Yuan Ma ◽  
Jun Ping Xiao
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Stability ◽  
First Principles ◽  
Phonon Dispersion ◽  
Type Structure ◽  
First Principles Calculations ◽  
Phonon Dispersion Curves ◽  
Elevated Pressures ◽  
Cscl Type

An investigation on structural stability of LuN under high pressure has been conducted using first-principles calculations. At elevated pressures LuN is predicted to undergo a phase transition from NaCl-type structure (B1) into CsCl-type structure (B2). The predicted transition pressure is 220 GPa. The phonon dispersion curves of B1 and B2 at 0 and 220 GPa are presented.

scholarly journals First-Principles Calculation for the Influence of C and O on the Mechanical Properties of γ-TiAl Alloy at High Temperature

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 262
Author(s):  
Jiahua Wang ◽  
Yong Lu ◽  
Xiaohong Shao
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
First Principles ◽  
Tial Alloy ◽  
Mechanical Performance ◽  
Phonon Dispersion ◽  
External Pressure ◽  
First Principles Calculation ◽  
Insight Into ◽  
Phonon Dispersion Relations

The elastic constants of temperature dependence, thermal expansion coefficient and phonon dispersion relations of γ-TiAl doped with C/O have been investigated using first-principles calculations in order to gain insight into the mechanical performance of γ-TiAl in cases of high temperature. This study shows that γ-TiAl maintains stability at high temperatures introduced by C or O atoms. Importantly, the hardness increases and retains excellent resistance to external pressure. The results indicate that even if the TiAl alloy is doped with C or O atoms, it can also exhibit excellent mechanical properties at a high temperature.

First-principles screening calculation of the surface phonon dispersion curves at the (100) surface of sodium

1990 ◽  
Vol 7 (3) ◽  
pp. 215-218
Author(s):  
A.A. Quong ◽  
R.F. Wallis ◽  
A.A. Maradudin ◽  
J.A. Gaspar ◽  
A.G. Eguiluz ◽  
...  
Keyword(s):  
First Principles ◽  
Phonon Dispersion ◽  
Dispersion Curves ◽  
Phonon Dispersion Curves ◽  
Surface Phonon

Mechanical, Dynamical and Thermodynamic Properties of Al-3wt%Mg from First Principles

2017 ◽  
Vol 72 (6) ◽  
pp. 527-534 ◽  
Author(s):  
Rong Yang ◽  
Bin Tang ◽  
Tao Gao
Keyword(s):  
Thermodynamic Properties ◽  
Density Of States ◽  
First Principles ◽  
Phonon Dispersion ◽  
Ambient Pressure ◽  
Structural Parameter ◽  
Partial Density ◽  
Phonon Dispersion Curves ◽  
Hardening Mechanisms ◽  
Good Agreement

AbstractThe mechanical, dynamical and thermodynamic properties of Al-3wt%Mg have been investigated using the first-principles method. The calculated structural parameter is in good agreement with previous works. Results for the elastic modulus, stress-strain relationships, ideal tensile and shear strengths are presented. Al-3wt%Mg is found to have larger moduli and higher strengths than Al, which is consistent with its exploitation in Al precipitate-hardening mechanisms. The partial density of states (PDOS) show that the partly covalent-like bonding through Al p-Mg s hybridization is the origin of excellent mechanical properties of Al-3wt%Mg. The phonon dispersion curves indicate that Al-3wt%Mg is dynamically stable at ambient pressure and 0 K. Furthermore, the Helmholtz free energy ΔF, the entropy S, the constant-volume specific heat CV and the phonon contribution to the internal energy ΔE are predicted using the phonon density of states. We expect that our work can provide useful guidance to help with the performance of Al-3wt%Mg.

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