Lattice dynamics and elastic properties of lanthanum monopnictides

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Lattice dynamics and elastic properties of lanthanum monopnictides.pdf (599.21 KB)

Date

2008

Authors

Gökoǧlu G.
Erkişi, A.

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Source Title

Solid State Communications

Print ISSN

0038-1098

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Volume

147

Issue

5-6

Pages

221 - 225

Language

English

Type

Article

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Abstract

In this study, first principles calculation results of the second order elastic constants and lattice dynamics of two lanthanum monopnictides, LaN and LaBi, which crystallize in rock-salt structure (B1 phase), are presented. Calculations were based on plane wave basis sets and pseudopotential methods in the framework of Density Functional Theory (DFT) with generalized gradient approximation. Elastic constants are calculated by tetragonal and orthorhombic distortions on cubic structure. Phonon dispersion spectra was constructed in the linear response approach of the Density Functional Perturbation Theory (DFPT). The complete phonon softening with negative frequencies and large elastic anisotropy were observed for LaN single crystal as a sign of the structural instability. The phonon dispersion curve for LaBi is typical for lanthanum monopnictides and does not show any anomalous physical property. The calculated structural quantities for both LaN and LaBi systems agree well with the available experimental and theoretical data. © 2008 Elsevier Ltd. All rights reserved.

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Keywords

A. Metals , D. Elasticity , D. Phonons , Acoustic dispersion , Calculations , Computational geometry , Crystal lattices , Crystallography , Cubic boron nitride , Dispersion (waves) , Dynamical systems , Dynamics , Elastic constants , Error analysis , Gradient methods , Lanthanum , Lanthanum alloys , Lattice constants , Lattice vibrations , Local area networks , Mechanics , Molecular orbitals , Perturbation techniques , Phonons , Physical properties , Probability density function , Set theory , Single crystals , Solids , Strain measurement , Structural properties , B1 phase , Cubic structures , Density functional perturbation theory (DFPT) , Density-functional theory (DFT) , Elastic anisotropy , Elastic properties , Elsevier (CO) , First-principles calculations , Generalized gradient (GGA) approximations , Lattice dynamics , Linear response (LR) approach , Monopnictides , Phonon dispersions , Phonon softening , Plane wave basis , Property (S) , Pseudo-potential methods , Rocksalt (RS) structure , Second order elastic constants , Structural instabilities , Density functional theory

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http://hdl.handle.net/11693/23055

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http://dx.doi.org/10.1016/j.ssc.2008.05.013

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Department of Physics