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Role of vibrations in electronic structure. Electronic structure for T=0 Sometimes considered Effect of zero-point vibrations on lattice parameters. I ndirect impact. Zero-point motion. I ndirect impact. Zero point motion. I ndirect impact. Zero point vibrations - PowerPoint PPT Presentation
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Role of vibrationsin electronic
structure
Electronic structure for T=0
Sometimes consideredEffect of zero-point vibrations on lattice parameters
Indirect impact
Zero-point motion Indirect impact
Zero point motion Indirect impact
Zero point vibrations
Something to keep in mind when constructing and evaluating vdW functionals …
Indirect impact
Be careful comparing with experiment!
Electronic structure for T=0
Sometimes consideredEffect of zero-point vibrations on lattice parameters
Long time ignoredEffect of zero-point vibrations on band gaps
Band gaps
Optical gaps
Electronic structure for T>0
Pragmatic approach:Temperature-dependent lattice parametersTemperature smearing to determine Fermi energyVibrational effects ignored
Beyond that:Quasi-harmonic approximation to lattice expansionRenormalization and manybody effects in electronic bandsImpact on optical exciations …Impact on transport …
PhotoemissionQuasiparticle bands
hn
v
c
N-1 electrons
Accepted
Quasiparticle bandsQuasiparticle equation
Kohn-Sham equation
G0W0
GW … iterative proceedures
Sx +Sc
Quasiparticle bandsDyson equation
carries, in principle, the information about ALL kinds of interactionsWhat about phonons?
SWhy should GW results agree with experiment?
Experimental evidenceSplitting of surface bandEvidence for phononic origin: isotope effect
H@W(110) D@W(110)
E. Rotenberg, J. Schaefer, and S. D. Kevan, PRL 84, 2925 (2000).
Spe
ctra
l fun
ctio
n A
(w)
D@W(110)
Experimental evidenceAll about kinks …
Experimental evidence of MB effects… and waterfalls
What about theory?
Green function approach to polaronsSolution of complex Dyson equation
Photo-absorptionExciton formation
hn
v
c
Phonon effects in exciton spectra
include exciton-phonon couplingBUT do not include excited-state geometry
Phonon effects in exciton spectraExcited-state forces
…. open perspectives to photoluminescence
Summary & outlook
Sx +Sc
eSph
ERQP + i EI
QP
te tph
wph
renormalization
Ee-h te-h
Fe-h
Ee-h transport
Etot
excitations
geometry
Program
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