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Computational Materials Science. 01/2011; Volume 50(, Issue 5,):1701.
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ABSTRACT: We have studied the vibrational properties of the filled tetrahedral semiconductor LiMgAs and its binary analog AlAs by using the plane-wave pseudopotential method within density functional theory. The calculated lattice constants for the studied compounds are in good agreement with previous theoretical and experimental results. The phonon dispersion curves and phonon density of states are calculated by using density functional perturbation theory. The sound speeds in different directions are quantitatively similar in LiMgAs and AlAs. The assignment of the zone center modes to the relative motion of the atoms shows that the lower optic modes are due to the Mg-As pair vibrations, while for the upper ones the Li-Mg pair dominates, which is attributed to the smaller Mg atom mass. The longitudinal interatomic force constant of Mg-As is about 66% higher than that of Li-As, showing the relatively high covalency of the former bond.
Journal of Physics Condensed Matter 07/2009; 21(30):305402. · 2.55 Impact Factor
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ABSTRACT: First principles calculations, by means of the full-potential linearized augmented plane wave method within the local density approximation, were carried out for the electronic and optical properties of the filled tetrahedral compounds LiMgN, LiMgP and LiMgAs. The bandgap trend in the ternaries is found to be similar to the one encountered in the zinc-blende AlX. The assignment of the structures in the optical spectra and band structure transitions are investigated in detail. The predicted values of the dielectric constants for LiMgN, LiMgP and LiMgAs are close to those of the binary compounds AlN, AlP and AlAs.
Journal of Physics Condensed Matter 07/2006; 18(31):7237. · 2.55 Impact Factor
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ABSTRACT: We report on first principles studies of the electronic properties of the filled tetrahedral compound LiCdP and zinc–blende InP, using the full potential linearized augmented plane wave method within the local density approximation. The total energy calculations show that the α phase (Li+ near the anion) to be more stable than the β one (Li+ near the cation) for the LiCdP. The conduction band valleys follow the Γ–L–X ordering of increasing energy for β-LiCdP and InP, and the Γ–X–L one for α–LiCdP. The conduction band modifications are discussed and found to obey the interstitial insertion rule except for the Γ state of β-LiCdP. The valence charge density analysis shows that the Cd–P bond is covalent whereas the Li–P and the Li–Cd ones in α and β phases, respectively, are ionic.
Computational Materials Science. 43(4):791-795.
