scholarly journals First Principles Computations of Second-Order Elastic Constants (SOEC) and Equations of State of Rutile TiO2

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Ghous Narejo ◽  
Warren F. Perger
Keyword(s):  
Equation Of State ◽  
Elastic Constants ◽  
First Principles ◽  
Equations Of State ◽  
Second Order ◽  
Lattice Parameters ◽  
Experimental Results ◽  
Basis Sets ◽  
Computational Results ◽  
Rutile Tio2

First principles computations of second-order elastic constants (SOECs) and bulk moduli (B) are carried out by ELASTCON and equation of state (EOS) programs. Computational results of lattice parameters, elastic constants, and bulk moduli are obtained with a wide variety of potentials and a limited combination of basis sets and are compared with computational and experimental results by other researchers in the field. DFT hybrid potentials provided the best comparison with the experiment.

FIRST-PRINCIPLES HIGH-PRESSURE ELASTIC AND THERMODYNAMIC PROPERTIES OF TANTALUM

2011 ◽  
Vol 25 (10) ◽  
pp. 1393-1407 ◽  
Author(s):  
JING-HE WU ◽  
XIAN-LIN ZHAO ◽  
YOU-LIN SONG ◽  
GUO-DONG WU
Keyword(s):  
Thermodynamic Properties ◽  
Elastic Constants ◽  
First Principles ◽  
Equations Of State ◽  
Debye Model ◽  
Thermal Expansivity ◽  
Orbital Method ◽  
Full Potential ◽  
Body Centered Cubic ◽  
Theoretical Results

The all-electron full-potential linearized muffin-tin orbital method, by means of quasi-harmonic Debye model, is applied to investigate the elastic constant and thermodynamic properties of body-centered-cubic tantalum (bcc Ta). The calculated elastic constants of bcc Ta at 0 K is consistent with the previous experimental and theoretical results. Our calculations give the correct trends for the pressure dependence of elastic constants. By using the convenient quasi-harmonic Debye model, we refined the thermal equations of state. The thermal expansivity and some other thermal properties agree well with the previous experimental and theoretical results.

Mixing and the Jet Flap

1956 ◽  
Vol 7 (2) ◽  
pp. 85-105 ◽  
Author(s):  
B. S. Stratford
Keyword(s):  
First Principles ◽  
Second Order ◽  
Experimental Results ◽  
Order Effects ◽  
List Type ◽  
Two Dimensional ◽  
Form Drag ◽  
First Approximation ◽  
Close Proximity ◽  
Thrust Characteristics

SummaryOne of the main problems associated with the “ Jet Flap ” concerns the discrepancy in thrust between idealised theory and the experimental results. This discrepancy is attributable to the mixing with the surrounding flow of the thin two-dimensional jet while still in close proximity to the aerofoil. The effect of the mixing may be calculated to a first approximation from a formula derivable from first principles, while certain second order effects, which can be significant, may be considered qualitatively.It is concluded that.(i) the full thrust should be experienced by a jet flapped aircraft at cruise,(ii) it should be possible to attain a low form drag at cruise in comparison with a conventional aircraft,(iii) at take-off, an aircraft using a shrouded jet flap would have better thrust recovery than one using a pure jet flap (which shows appreciable losses),(iv) the use of by-pass engines would further improve the thrust characteristics,(v) the practical gains from thrust augmentation, as obtained by controlling the mixing, seem likely to be small.

ElaStic: A tool for calculating second-order elastic constants from first principles

2013 ◽  
Vol 184 (8) ◽  
pp. 1861-1873 ◽  
Author(s):  
Rostam Golesorkhtabar ◽  
Pasquale Pavone ◽  
Jürgen Spitaler ◽  
Peter Puschnig ◽  
Claudia Draxl
Keyword(s):  
Elastic Constants ◽  
First Principles ◽  
Second Order

scholarly journals Nonlinear Elasticity of Borocarbide Superconductor YNi2B2C: A First-Principles Study

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Lili Liu ◽  
Cai Chen ◽  
Dingxing Liu ◽  
Zhengquan Hu ◽  
Gang Xu ◽  
...  
Keyword(s):  
High Pressure ◽  
Elastic Constants ◽  
Vickers Hardness ◽  
First Principles ◽  
Second Order ◽  
First Principles Calculations ◽  
Modulus Ratio ◽  
Third Order ◽  
Lattice Constants ◽  
Third Order Elastic Constants

First-principles calculations combined with homogeneous deformation methods are used to investigate the second- and third-order elastic constants of YNi2B2C with tetragonal structure. The predicted lattice constants and second-order elastic constants of YNi2B2C agree well with the available data. The effective second-order elastic constants are obtained from the second- and third-order elastic constants for YNi2B2C. Based on the effective second-order elastic constants, Pugh’s modulus ratio, Poisson’s ratio, and Vickers hardness of YNi2B2C under high pressure are further investigated. It is shown that the ductility of YNi2B2C increases with increasing pressure.

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