[Pw_forum] electron-phonon coefficients

[Ion Errea]

Dear PWscf users,

Lately I am trying to calculate a rough estimation of the
superconducting transition temperature of a Li-Be alloy under pressure.
For that goal, I calculated using the espresso code the electron-phonon
coupling constant, lambda, and the Eliashberg function, a2F. Thus I
should be able to calculate Tc via the McMillan equation.

I am writing a simple fortran program to calculate the average phonon
frequency, involved in the McMillan equation, from a integration of the
values obtained for a2F in the output. Nevertheless, I got a result that
I did not expect at all for the average phonon frequency. To check the
reliability of my naive program, I calculated lambda from the a2F values
as well. Curiously, I obtained a lambda 2pi times the lambda given in
the output. Checking the theory I realised that there is a 2pi factor
dividing in the Eliashberg function. 

I am just wondering whether this 2pi factor is implemented in the a2F
output, or it is incorporated afterwards when lambda is calculated. I
guess the latter is the correct answer since such casualities are not
too common. Anyway, my program could perfectly be wrong. I would be very
grateful if someone would confirm my supposition.

Regards,

Ion

-- 
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Ion Errea Lope
Materia Kondentsatuaren Fisika Saila
Zientzia eta Teknologia Fakultatea
Euskal Herriko Unibertsitatea 
644 Posta Kutxatila, 48080 Bilbo, Spain

Telefonoa: +34 946015322
Mail: ierrea001 at ikasle.ehu.es
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