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[zhangting <zhangting@pku.edu.cn>]

Dear ABINIT users:

        I'm studying to perform e-ph coupling calculations with ABINIT code, 
and I've some questions.I have already read
the article "Linear-response calculation of electron-phonon coupling 
parameters"(PRB 53,R7575), in which the basic method embedded in ABINIT code 
to calculate e-ph values are showed. And I also have read the Mahan's 
"Many-particle Physics".
    In PRB 53,R7575, the scatting matrix element of e-ph Hamiltonian seems 
have no relation to the phonon amplitude?  In the article, equation (1), the 
Hamiltonian in the middle is just the phonon polarization vector times the 
gradient of the self-consistent potential. This is quite different compared 
with the equations in Mahan's "Many particle Physics".
    In Mahan's description, the Hamiltonian itself should be proportional to 
the phonon amplitude.
    What does this difference mean?

    Another question: Also in the PRB article,equation (2), there are two 
delta function delta(Enk-Ef)*delta(En'k'-Ef). Does this mean before and after 
scattering with phonon,the electron states should both have the same 
energy,which equals to Ef? This is strange. I'm interesting in the scatting 
of phonons and non-equilibrium "hot" electrons, If the ABINIT code could only 
handle the e-ph coupling just at the fermi level, it will be a great 
depression to me.

    The third question: dose the GKK file contain the scattering matrix 
elements? I can't understand its format.Can someone tell me how the bulk 
S-matrix data organised in the GKK file? Can I find a detailed explaination 
of the format,and the meaning of date in such *.ep_* files?

    The PRB article and a GKK file are attached. Thanks a lot!   

　　　　　　　
                                

　　　　　　　　zhangting
　　　　　　　　zhangting@pku.edu.cn
　　　　　　　　　　2006-05-21

Attachment: PRB_53_R7575_Linear-response calculation of electron-phonon coupling parameters.pdf
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Attachment: CsCl-ep_GKK.ascii
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