Guys, I have two questions:(adsbygoogle = window.adsbygoogle || []).push({});

(1) what does a vanishing Fermi energy mean?

(2) I have also calculated the phonon self energy for the electron phonon interaction in graphene. However in one of the papers, they state that one needs to subtract from this self energy the case of vanishing Fermi level and Born oppenheimer approximation ( where [tex]\omega[/tex]=0 and large vector k and so they introduced a cut off energy equal to half of the [tex]\pi[/tex]- band width. The reason behind that, as they say, is that this contribution is already included in the definition of the frequency [tex]\omega[/tex] in graphene and has to be taken off to avoid double counting. Can anyone give me an idea of why this is the case...

Thanks...

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# Vanishing fermi level and cut off value in self energy

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