Lattice dynamics of palladium in the presence of electronic correlations

W. H. Appelt, A. Östlin, I. Di Marco, I. Leonov, M. Sekania, D. Vollhardt, and L. Chioncel

Phys. Rev. B 101, 075120 – Published 18 February 2020

Abstract

We compute the phonon dispersion, density of states, and the Grüneisen parameters of bulk palladium in the combined density functional theory (DFT) and dynamical mean-field theory. We find good agreement with experimental results for ground-state properties (equilibrium lattice parameter and bulk modulus) and the experimentally measured phonon spectra. We demonstrate that at temperatures $T ≲ 20 K$ the phonon frequency in the vicinity of the Kohn anomaly, $ω_{T 1} (q_{K})$ , strongly decreases. This is in contrast to DFT where this frequency remains essentially constant in the whole temperature range. Apparently, correlation effects reduce the restoring force of the ionic displacements at low temperatures, leading to a mode softening.

Received 3 December 2018
Revised 17 December 2019
Accepted 22 January 2020

DOI:https://doi.org/10.1103/PhysRevB.101.075120

Physics Subject Headings (PhySH)

Acoustic phonons Lattice dynamics

Elemental metals

Density functional theory Dynamical mean field theory Hubbard model

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

W. H. Appelt^1,2, A. Östlin ³, I. Di Marco ^4,5,6, I. Leonov^7,8, M. Sekania^3,9, D. Vollhardt³, and L. Chioncel ^2,3

¹Theoretical Physics II, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany
²Augsburg Center for Innovative Technologies, University of Augsburg, D-86135 Augsburg, Germany
³Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany
⁴Asia Pacific Center for Theoretical Physics, Pohang, Gyeonbuk 790-784, Republic of Korea
⁵Department of Physics, POSTECH, Pohang, Gyeonbuk 790-784, Republic of Korea
⁶Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden
⁷Institute of Metal Physics, Sofia Kovalevskaya Street 18, 620219 Yekaterinburg GSP-170, Russia
⁸Ural Federal University, 620002 Yekaterinburg, Russia
⁹Andronikashvili Institute of Physics, Tamarashvili 6, 0177 Tbilisi, Georgia

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Vol. 101, Iss. 7 — 15 February 2020

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