1. Electronic and phononic properties of [V.sub.2]A1C via first principles
- Author
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Yang, Z.J., Li, J., Linghu, R.F., Song, X.S., Cheng, X.L., and Yang, X.D.
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Electron configuration -- Research ,Binding energy -- Research ,Molecular physics -- Research ,Physics - Abstract
The electronic and phononic properties of [V.sub.2]A1C have been extensively studied using ab initio pseudopotential density functional theory. Our investigations revealed that the longest V-V bond and its least variations have led to the stiffer c axis. The nearly unchanged net charge of the C atom under pressure has led to nearly unchanged overlapped populations along the C-V bond. The obvious charge transfer of V → Al has induced significant variations of the overlapped populations along Al-V and V-V bonds. An anomalous variation of charge transfer between V and Al atoms and V-V bond populations at about 700 GPa has been revealed, which may relate to its structural instability at about 731 GPa. Previously calculated structural instability at about 731 GPa has been successfully confirmed by the present phonon dispersion curve. The bonding natures are also studied by the electron density difference, electron density of states, and the energy band structure. PACS Nos.: 63.20.D-, 71.20.-b, 71.15.Mb. Nous avons fait une etude en profondeur des proprietes de [V.sub.2]A1C en utilisant la theorie de la fonctionnelle de densite avec pseudo-potentiel ab initio. Notre etude revele que le plus grand lien V-V et sa petite variation sont responsables de la forte rigidite de l'axe c. La charge nette de l'atome C ne change pratiquement pas sous la pression, indiquant une constance des populations de recouvrement dans le lien C-V. L'evident transfert de charges V → Al induit des variations significatives des populations de recouvrement dans les liens V-Al et V-V. Nous notons une variation anomale de transfert de charges entre les atomes V et Al autour de 700 GPa, ce qui pourrait etre relie a l'instabilite structurelle observee a 731 GPa. Des calculs anterieurs de cette instabilite structurelle a 731 GPa ont ete confirmes avec succes par notre courbe de dispersion des phonons. Nous etudions egalement la nature des liens a l'aide de la difference dans la densite electronique, de la densite d'etats electroniques et de la structure des bandes d'energie. [Traduit par la Redaction], 1. Introduction The [M.sub.n+1]A[X.sub.n] phases, where M is an early transition metal, A is an A-group element (mostly IIIA and IVA elements), X is either C or N, and n [...]
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- 2013
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