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Interplay of force constants in the lattice dynamics of disordered alloys: An ab initio study

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Title Interplay of force constants in the lattice dynamics of disordered alloys: An ab initio study
 
Creator CHOUHAN, RK
ALAM, A
GHOSH, S
MOOKERJEE, A
 
Subject TOTAL-ENERGY CALCULATIONS
WAVE BASIS-SET
PHONON-DISPERSION
1ST-PRINCIPLES
SYSTEM
 
Description A reliable prediction of interatomic force constants in disordered alloys is an outstanding problem. This is due to the need for a proper treatment of multisite (at least pair) correlation within a random environment. The situation becomes even more challenging for systems with a large difference in atomic size and mass. We propose a systematic density functional theory (DFT) based study to predict the ab initio force constants in random alloys. The method is based on a combination of special quasirandom structures and the augmented space recursion to calculate phonon spectra, density of states (DOS), etc. The bcc TaW and fcc NiPt alloys are considered as the two distinct test cases. The Ta-Ta (W-W) bond distance in the alloy is predicted to be smaller (larger) than those in pure Ta (W), which, in turn, yields stiffer (softer) force constants for Ta (W). Pt-Pt force constants in the alloy, however, are predicted to be softer compared to Ni-Ni, due to the large bond distance of the former. Our calculated force constants, phonon spectra, and DOS are compared with experiments and other theoretical results, wherever available. A correct trend of the present results for the two alloys paves a path for future studies in more complex alloy systems.
 
Publisher AMER PHYSICAL SOC
 
Date 2014-12-28T13:12:12Z
2014-12-28T13:12:12Z
2014
 
Type Article
 
Identifier PHYSICAL REVIEW B, 89(6)
1098-0121
1550-235X
http://dx.doi.org/10.1103/PhysRevB.89.060201
http://dspace.library.iitb.ac.in/jspui/handle/100/16685
 
Language English