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SUMMARY:Effective phonons for finite-temperature Raman spectroscopy from f
 irst principles: GaN and BaZrS3 - Dr. Florian Knoop\, Linköping Universit
 y
DTSTART:20240610T133000Z
DTEND:20240610T140000Z
UID:TALK217306@talks.cam.ac.uk
CONTACT:Dr Philipp Pracht
DESCRIPTION:Ab initio simulations of Raman spectroscopy are often performe
 d within the harmonic approximation\, which is insufficient for describing
  spectral properties of materials at realistic conditions. Here we present
  a numerically efficient scheme that couples ab initio simulations\, equiv
 ariant neural network potentials\, and self-consistent phonon theory in th
 e temperature-dependent effective potentials (TDEP) framework to perform p
 recise simulations of Raman response at finite temperature [1\, 2\, 3]. Th
 e method is presented for wurtzite GaN in comparison to latest experimenta
 l results\, with a focus on the rigorous treatment of direction and polari
 zation-orientation (PO) dependence in optically anisotropic solids\, which
  is crucial to discern crystallographic orientations and enable mode assig
 nment. We discuss the importance of the interplay between harmonic dispers
 ive properties and anharmonic interaction strength for properties primaril
 y attributed to anharmonicity\, such as linewidth broadening and thermal c
 onductivity [4\, 5\, 6]. We subsequently apply the developed approach to a
  complex material\, the highly polarizable yet lead-free chalcogenide Pero
 vskite BaZrS3\, and discuss how Raman spectroscopy and phonon theory can h
 elp to shed light on the microscopic mechanisms influencing its optoelectr
 onic performance [7].\n\n[1] FK et al.\, J. Open Source Softw 9\, 6150 (20
 24)\; https://tdep-developers.github.io/tdep/\n[2] MF Langer\, JT Frank\, 
 FK\, J. Chem. Phys. 159\, 174105 (2023)\n[3] N Benshalom\, et al.\, Phys R
 ev Mater 6\, 033607 (2022)\n[4] FK\, et al.\, Phys Rev Mater 4\, 083809 (2
 020)\n[5] AH Romero et al.\, Phys Rev B 91\, 214310 (2015)\n[6] FK\, et al
 .\, Phys Rev 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=RkhaYkM5VTZPZ3pYSHpt
 UXlRSkppQT09
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