Elasticity and Debye temperature of defected fcc crystals (AlCu3, Al, Cu): Molecular dynamics and first-principles calculations

2015 ◽  
Vol 109 ◽  
pp. 194-199 ◽  
Author(s):  
B. Romanowski ◽  
D. Chrobak ◽  
J. Räisänen ◽  
R. Nowak
Keyword(s):  
Molecular Dynamics ◽  
Debye Temperature ◽  
First Principles ◽  
First Principles Calculations

Structural, elastic and thermodynamic properties of A15-type compounds V3X (X = Ir, Pt and Au) from first-principles calculations

2016 ◽  
Vol 30 (35) ◽  
pp. 1650414 ◽  
Author(s):  
Mingliang Wang ◽  
Zhe Chen ◽  
Dong Chen ◽  
Cunjuan Xia ◽  
Yi Wu
Keyword(s):  
Thermodynamic Properties ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Coefficient Of Thermal Expansion ◽  
Local Density ◽  
Debye Model ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Experimental Values

The structural, elastic and thermodynamic properties of the A15 structure V3Ir, V3Pt and V3Au were studied using first-principles calculations based on the density functional theory (DFT) within generalized gradient approximation (GGA) and local density approximation (LDA) methods. The results have shown that both GGA and LDA methods can process the structural optimization in good agreement with the available experimental parameters in the compounds. Furthermore, the elastic properties and Debye temperatures estimated by LDA method are typically larger than the GGA methods. However, the GGA methods can make better prediction with the experimental values of Debye temperature in V3Ir, V3Pt and V3Au, signifying the precision of the calculating work. Based on the E–V data derived from the GGA method, the variations of the Debye temperature, coefficient of thermal expansion and heat capacity under pressure ranging from 0 GPa to 50 GPa and at temperature ranging from 0 K to 1500 K were obtained and analyzed for all compounds using the quasi-harmonic Debye model.

Discrete breathers modeling from first principles in graphene and in classical approximation in fcc Ni: Comparison

2019 ◽  
Vol 04 (02) ◽  
pp. 1950002 ◽  
Author(s):  
Ivan P. Lobzenko
Keyword(s):  
Molecular Dynamics ◽  
First Principles ◽  
High Frequency ◽  
Normal Modes ◽  
Nonlinear Normal Modes ◽  
First Principles Calculations ◽  
Discrete Breathers ◽  
Points Of View ◽  
Nonlinear Normal ◽  
Dynamics Simulations

Properties of discrete breathers are discussed from two points of view: (I) the ab initio modeling in graphene and (II) classical molecular dynamics simulations in the ace-centered cubic (fcc) Ni. In the first (I) approach, the possibility of exciting breathers depends on the strain applied to the graphene sheet. The uniaxial strain leads to opening the gap in the phonon band and, therefore, the existence of breathers with frequencies within the gap. In the second (II) approach, the structure of fcc Ni supports breathers of another kind, which possess a hard nonlinearity type. It is shown that particular high frequency normal mode can be used to construct the breather by means of overlaying a spherically symmetrical function, the maximum of which coincides with the breather core. The approach of breathers excitation based on nonlinear normal modes is independent of the level of approximation. Even though breathers could be obtained both in classical and first-principles calculations, each case has advantages and shortcomings, that are compared in the present work.

FIRST-PRINCIPLES CALCULATIONS OF STRUCTURE, STABILITY AND THERMODYNAMIC PROPERTIES OF fcc-6LiT UNDER HIGH TEMPERATURES AND PRESSURES

2011 ◽  
Vol 25 (05) ◽  
pp. 333-344 ◽  
Author(s):  
CHENGHUA HU ◽  
FENG WANG ◽  
CHUANHUI XIA ◽  
ZHOU ZHENG ◽  
WEIYI REN
Keyword(s):  
Heat Capacity ◽  
Melting Point ◽  
Thermodynamic Properties ◽  
Debye Temperature ◽  
High Temperatures ◽  
First Principles ◽  
Critical Pressure ◽  
Structure Stability ◽  
First Principles Calculations ◽  
Different Temperatures

We perform first-principles calculations for fcc-6 LiT in order to study its structure, stability and thermodynamic properties under high temperatures and pressures. We find that melting point of 6 LiT (0 GPa) is about 680 K, and rise with the pressures. Reverse equivalent pressure P r and critical pressure P c of different temperatures are predicted from [Formula: see text] or [Formula: see text], and they are found to increase with temperature. 6 LiT should be stable under the condition of P < 80 GPa and T < 680 K . We also find that pressure and temperature will cause different effect of shear on the {100} and {110} planes. Heat capacity of different pressures increase with temperature and closes to the Dulong–Petit limit at higher temperatures. Debye temperature decreases with temperature, and increases with pressure.

Preparation, Structure, And Electronic Properties Of Amorphous Gaas By Tight-Binding Molecular Dynamics

1993 ◽  
Vol 321 ◽  
Author(s):  
C. Molteni ◽  
L. Colombo ◽  
L. Miglio
Keyword(s):  
Molecular Dynamics ◽  
First Principles ◽  
Large Scale ◽  
Tight Binding ◽  
Computer Experiment ◽  
Dynamics Simulation ◽  
First Principles Calculations ◽  
Amorphous Network ◽  
Large Scale Simulations

ABSTRACTWe investigate the short-range structural properties of a-GaAs as obtained in a computer experiment based on a tight-binding molecular dynamics simulation. The amorphous configuration is obtained by quenching a liquid sample well equilibrated at T=1600 K. A detailed characterization of the topology and defect distribution of the amorphous network is presented and discussed. The electronic structure of our sample is calculated as well. Finally, we discuss the reliability and transferability of the present computational scheme for large-scale simulations of compound semiconductor materials by comparing our results to first-principles calculations.

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