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CATEGORIES:Lennard-Jones Centre
SUMMARY:Effective phonons for finite-temperature Raman spe
 ctroscopy from first principles: GaN and BaZrS3 - 
 Dr. Florian Knoop\, Linköping University
DTSTART;TZID=Europe/London:20240610T143000
DTEND;TZID=Europe/London:20240610T150000
UID:TALK217306AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/217306
DESCRIPTION:Ab initio simulations of Raman spectroscopy are of
 ten performed within the harmonic approximation\, 
 which is insufficient for describing spectral prop
 erties of materials at realistic conditions. Here 
 we present a numerically efficient scheme that cou
 ples ab initio simulations\, equivariant neural ne
 twork potentials\, and self-consistent phonon theo
 ry in the temperature-dependent effective potentia
 ls (TDEP) framework to perform precise simulations
  of Raman response at finite temperature [1\, 2\, 
 3]. The method is presented for wurtzite GaN in co
 mparison to latest experimental results\, with a f
 ocus on the rigorous treatment of direction and po
 larization-orientation (PO) dependence in opticall
 y anisotropic solids\, which is crucial to discern
  crystallographic orientations and enable mode ass
 ignment. We discuss the importance of the interpla
 y between harmonic dispersive properties and anhar
 monic interaction strength for properties primaril
 y attributed to anharmonicity\, such as linewidth 
 broadening and thermal conductivity [4\, 5\, 6]. W
 e subsequently apply the developed approach to a c
 omplex material\, the highly polarizable yet lead-
 free chalcogenide Perovskite BaZrS3\, and discuss 
 how Raman spectroscopy and phonon theory can help 
 to shed light on the microscopic mechanisms influe
 ncing its optoelectronic performance [7].\n\n[1] F
 K et al.\, J. Open Source Softw 9\, 6150 (2024)\; 
 https://tdep-developers.github.io/tdep/\n[2] MF La
 nger\, JT Frank\, FK\, J. Chem. Phys. 159\, 174105
  (2023)\n[3] N Benshalom\, et al.\, Phys Rev Mater
  6\, 033607 (2022)\n[4] FK\, et al.\, Phys Rev Mat
 er 4\, 083809 (2020)\n[5] AH Romero et al.\, Phys 
 Rev B 91\, 214310 (2015)\n[6] FK\, et al.\, Phys R
 ev Lett 130\, 236301 (2023)\n[7] K Ye\, M Menahem\
 , T Salzillo\, FK\, et al.\, arXiv 2402.18957\n
LOCATION:Zoom link: https://zoom.us/j/92447982065?pwd=RkhaY
 kM5VTZPZ3pYSHptUXlRSkppQT09
CONTACT:Dr Philipp Pracht
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