scholarly journals Theoretical Study on Radiationless Decay in Butadiene Isomerization Case using First-principles Calculation

2020 ◽  
Vol 1445 ◽  
pp. 012008
Author(s):  
R N Fadilla ◽  
A N Jannah ◽  
F N Febriana ◽  
S Munir ◽  
A H Zaidan
Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2091 ◽  
Author(s):  
Tie Yang ◽  
Liyu Hao ◽  
Rabah Khenata ◽  
Xiaotian Wang

In this work, we systematically studied the structural, electronic, magnetic, mechanical and thermodynamic properties of the fully compensated spin-gapless inverse Heusler Ti2MnAl compound under pressure strain condition by applying the first-principles calculation based on density functional theory and the quasi-harmonic Debye model. The obtained structural, electronic and magnetic behaviors without pressure are well consistent with previous studies. It is found that the spin-gapless characteristic is destroyed at 20 GPa and then restored with further increase in pressure. While, the fully compensated ferromagnetism shows a better resistance against the pressure up to 30 GPa and then becomes to non-magnetism at higher pressure. Tetragonal distortion has also been investigated and it is found the spin-gapless property is only destroyed when c/a is less than 1 at 95% volume. Three independent elastic constants and various moduli have been calculated and they all show increasing tendency with pressure increase. Additionally, the pressure effects on the thermodynamic properties under different temperature have been studied, including the normalized volume, thermal expansion coefficient, heat capacity at constant volume, Grüneisen constant and Debye temperature. Overall, this theoretical study presents a detailed analysis of the physical properties’ variation under strain condition from different aspects on Ti2MnAl and, thus, can provide a helpful reference for the future work and even inspire some new studies and lead to some insight on the application of this material.


2013 ◽  
Vol 740-742 ◽  
pp. 455-458 ◽  
Author(s):  
Shigenori Kato ◽  
Kenta Chokawa ◽  
Katsumasa Kamaiya ◽  
Kenji Shiraishi

We investigated the atomistic mechanism of N incorporation during SiC oxidation by the first principles calculation. We found that N atoms play two characteristic roles in NO oxidation of SiC surface. One is that N atoms tend to form three-fold coordinated covalent bonds on a SiC(0001) surface, which assist the termination of surface dangling bonds, leading to improve the interface properties. The other is that N atoms form N-N bond like a double bond. The N2 molecule is desorbed from SiC surface, which do not disturb the oxidation process of SiC surfaces. These results indicate that N incorporation is effective to suppress defect state generation at SiO2/SiC interfaces during SiC oxidation.


2005 ◽  
Vol 108-109 ◽  
pp. 193-198
Author(s):  
Sandrine Brochard ◽  
Julien Godet ◽  
Laurent Pizzagalli ◽  
Pierre Beauchamp ◽  
José Soler

Atomistic simulations using both semi-empirical potential and first principles calculation have been performed to study the initiation of plasticity near surface steps in silicon. A comparison of both techniques on a prototypic case shows qualitative and quantitative agreement. Then each method has been used to analyze in detail some characteristics of the surface step: the step geometry thanks to semi-empirical potential calculations, and the step reactivity with ab initio techniques.


2017 ◽  
Vol 31 (09) ◽  
pp. 1750080 ◽  
Author(s):  
Liang Sun ◽  
Yimin Gao ◽  
Katsumi Yoshida ◽  
Toyohiko Yano ◽  
Wen Wang

A theoretical study is conducted by first-principles theory to study the structural, electronic, elastic and thermal properties of Al4SiC4, Al4C3 and 4H-SiC phases under pressure. The calculated results indicated that the volumetric shrinkage of Al4SiC4 declines to 16% compared with 4H-SiC for 12% and its length of lattice parameter along c-axis decreases faster than that of along other axes in cell structures. The mechanical properties of Al4SiC4 like elastic constants and elastic moduli increase continuously under pressure. The thermal expansion coefficient of three compounds under pressure are studied first. When temperature is lower than 500 K, the coefficient increases rapidly first then gradually tends to a linear accession at higher temperature and the propensity of increment becomes moderate. The [Formula: see text] data decreases slightly with pressure but increases dramatically with temperature for all compounds.


2001 ◽  
Vol 15 (28n30) ◽  
pp. 3821-3824
Author(s):  
HIDEKI KATAGIRI ◽  
YUKIHIRO SHIMOI ◽  
SHUJI ABE

We performed a first-principles calculation of typical polydiacetylene (PDA), TCDU (poly(5,7-dodecadiyne-1,12-diyl-bis-phenylurethane)). Potential energy curves (PEC's) as a function of two bond lengths of the backbone chain are presented. The present PEC's show that TCDU has only an acetylene-type stable structure and a butatriene-type structure is unstable, consistent with our previous calculations with a geometry optimization procedure. This result is in contrast to the case of a hypothetical hydrogen-substituted PDA where a butatriene-type structure is obtained as a meta-stable structure.


1981 ◽  
Vol 42 (C6) ◽  
pp. C6-625-C6-627 ◽  
Author(s):  
P. E. Van Camp ◽  
V. E. Van Doren ◽  
J. T. Devreese

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