Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session Q48: Electrons, Phonons, Electron-Phonon Scattering, and Phononics IV
3:00 PM–5:48 PM,
Wednesday, March 16, 2022
Room: McCormick Place W-471A
Sponsoring Units: DCOMP DMP
Chair: Davide Donadio, University of California Davis
Abstract: Q48.00002 : Precisely and efficiently computing phonons via irreducible derivatives: characterizing soft modes*
3:12 PM–3:24 PM
problem, yet inadequacies in existing techniques continue to yield deficient
results in systems with sensitive phonons, like those with soft modes.
Here we circumvent this issue via the lone irreducible derivative (LID) and
bundled irreducible derivative (BID) approaches to computing phonons via finite
displacements, where the former optimizes precision and the latter, efficiency.
The strategy behind the irreducible approaches is to convert gains
in efficiency into enhanced accuracy. We illustrate our approach on two
prominent charge density wave systems, the shape memory alloy AuZn and the
vanadium based kagome metal KV3Sb5; in addition to metallic lithium.
LID is executed using energy and force derivatives, and practical guidelines
are developed. For BID, a bundled basis is derived guaranteeing minimal
propagation of error and maximal efficiency, and demonstrating that BID
faithfully reproduces the LID results. Comparing our resulting phonons in the
aforementioned crystals to the literature reveals nontrivial
inaccuracies in all cases. Our approaches' unbiased execution can be fully
automated, making it well suited for both niche systems of interest and big
*We acknowledge U.S. DOE OS grant DE-SC0016507.
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