Bulletin of the American Physical Society
2023 APS March Meeting
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session D61: Electrons, Phonons, Electron-Phonon Scattering and Phononics II
3:00 PM–6:00 PM,
Monday, March 6, 2023
Room: Room 418
Sponsoring
Unit:
DCOMP
Chair: Roxana Margine, Binghamton University
Abstract: D61.00001 : Phonon anharmonicity in quantum paraelectrics beyond density-functional theory*
3:00 PM–3:36 PM
Presenter:
Carla Verdi
(University of Sydney)
Author:
Carla Verdi
(University of Sydney)
In this talk, I will discuss an approach for calculating the temperature-dependent anharmonic properties of these materials with beyond density-functional theory accuracy. Specifically, we employ machine-learned potentials in combination with the stochastic self-consistent harmonic approximation. I will show that this method seamlessly allows to fully capture strong anharmonicities while retaining first-principles accuracy, and furthermore opens up the possibility to perform many-body calculations beyond DFT via Δ-machine learning. I will show that the paraelectric phase in KTaO3 and SrTiO3 is stabilized by anharmonic quantum fluctuations down to 0 K. In the case of SrTiO3, we further characterize the cubic to tetragonal transition by the softening of the antiferrodistortive instability. I will discuss how a quantitative description of the quantum paraelectric behavior requires a higher-level treatment of electronic correlation effects via the random phase approximation.
*Funding by the Austrian Science Fund (FWF) within projects SFB-F81 TACO and I 4506 (FWO-FWF joint project) and by the Australian Research Council (ARC) via DECRA Project No. DE220101147 is acknowledged.
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