The traped state of palaron in the band gap

[Taifeng Liu]

Hi All,
In the polaron calculation using EPW, it will produce the polaron eigenvalues. For the hole polaron calculations, this value was measured from the valence band top. I want to know the position of this value in the band gap. But there are calculated band gap and experimental band gap,which one shoud be used. In my optinion, I think the experimental band gap should be used. As in the solving of polaron equation, the self-interaction correction (SIC) is removed, this eigenvalue is reliable to the experiment. However, the calcualted band gap using PBE functional are much smaller. Do I understand this right? any explaining? Thank you.
Best wishes!
Taifeng Liu

[jlb]

Dear Taifeng Liu,
Thank you for your question.
Note that in the current implementation the self-interaction is removed for the extra electron (or hole). This means that the polaron eigenvalue, with respect to the conduction (or valence) edge, should be accurate. The value of the band gap itself, however, is inherited from the underlying DFT calculation. This means that the renormalization of the band gap due to polaron effects should be reliable, but that might not necessarily hold for the absolute value of the band gap.
Best regards,
Jon

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Jon Lafuente-Bartolome
Department of Physics, University of the Basque Country UPV/EHU