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Phonon broadening from supercell lattice dynamics: Random and correlated disorder

DOI: 10.1002/pssb.201600586 DOI Help

Authors: Alistair R. Overy (University of Oxford; Diamond Light Source) , Arkadiy Simonov (University of Oxford) , Philip A. Chater (Diamond Light Source) , Matthew G. Tucker (Oak Ridge National Laboratory) , Andrew L. Goodwin (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physica Status Solidi (b)

State: Published (Approved)
Published: November 2016

Abstract: We demonstrate how supercell implementations of conventional lattice dynamical calculations can be used to determine the extent and nature of disorder-induced broadening in the phonon dispersion spectrum of disordered crystalline materials. The approach taken relies on band unfolding, and is first benchmarked against virtual crystal approximation phonon calculations. The different effects of mass and interaction disorder on the phonon broadening are then presented, focussing on the example of a simple cubic binary alloy. For the mass disorder example, the effect of introducing correlated disorder is also explored by varying the fraction of homoatomic and heteroatomic neighbors. Systematic progression in the degree of phonon broadening, on the one hand, and the form of the phonon dispersion curves from primitive to face-centered cubic type, on the other hand, is observed as homoatomic neighbors are disfavored. The implications for rationalizing selection rule violations in disordered materials and for using inelastic neutron scattering measurements as a means of characterizing disorder are discussed.

Journal Keywords: disorder; lattice dynamics; thermoelectrics

Subject Areas: Physics

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