[Pw_forum] Question for electron phonon coulping

[ma Yanming]

Dear All,

I have a question concerning the electron-phonon coupling.
I increase the parameter "nsig' to 40 in elphon.f90.
So in my case I have 40 Gaussian Broadening steps. The calculated lambda(q) 
is negative number until 35 step, i.e.,   Gaussian Broadening: 0.35 Ry. 
>From step 36, the lambda(q) comes positive and increase gradully. Until 
step 40 it continue increasing. It seems that it still hasn't converged. I 
am not clear the principle for this Gaussian broadening procedures. In my 
case, the Fermi energy is around 19.47 eV. I am wondering if it is 
reasonable if I take the positive number (in the final 40 step) as final 
lambda value. But at the step 40, the calculated lambda is at fermi energy 
18.9 eV which is far away from 19.47eV.

Any idea on the principle for Gaussian broadening procedures. Can I take 
the positive lambda after 40 step Gaussian broadening and by 35 step 
negative number?

THanks



Yanming Ma PhD
Steacie Institute for Molecular Sciences,
National Research Councils of Canada.
100 Sussex
K1A 0R6

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