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DTSTART:20260329T030000
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BEGIN:VEVENT
DTSTAMP:20260310T221401Z
UID:1769680800@ist.ac.at
DTSTART:20260129T110000
DTEND:20260129T120000
DESCRIPTION:Speaker: Matthew Houtput\nhosted by Mikhail Lemeshko\nAbstract:
  Electron-phonon interactions are often written using the approximation of
  linear interaction\, where one only keeps the process where one electron 
 interacts with one phonon. This is usually sufficient to quantitatively de
 scribe material properties. However\, this is no longer true in anharmonic
  materials with significant electron-phonon interaction\, such as quantum 
 paraelectrics and halide perovskites. Currently\, the only available model
 s for nonlinear electron-phonon interaction are model Hamiltonians\, writt
 en in terms of phenomenological parameters. Here\, we provide a microscopi
 c semi-analytical expression for the long-range dipole part of the 1-elect
 ron-2-phonon matrix element\, which can be interfaced with first principle
 s techniques. We show that unlike for the long-range 1-electron-1-phonon i
 nteraction\, the continuum approximation is not sufficient and that the en
 tire phonon dispersion must be considered. We calculate an expression for 
 the quasiparticle energies and show that they can be written in terms of a
  1-electron-2-phonon spectral function. To demonstrate the method in pract
 ice\, we calculate the 1-electron-2-phonon spectral function for LiF and C
 sPbI3 from first principles\, and we show that the nonlinear interaction c
 ontributes significantly to the electron mobility of CsPbI3. The framework
  presented here bridges the gap between model Hamiltonians and first-princ
 iples calculations for the 1-electron-2-phonon interaction.
LOCATION:Office Bldg West / Ground floor / Foyer seminar room \, ISTA
ORGANIZER:Michaela.Pucher@ist.ac.at
SUMMARY:Matthew Houtput: First principles theory of nonlinear long-range el
 ectron-phonon interaction
URL:https://talks-calendar.ista.ac.at/events/6255
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