[Pw_forum] the unit of lambda

[Eyvaz Isaev]

Dear Guoying,

Merry Christmas, thanks!

Electron phonon coupling constant \lambda is a
dimensionless parameter by its definition. 
At low temperatures (T) experimental electronic
specific heat C_{el}(T) is defined as 
C_{el}(T) = const N(0) (1 + \lambda) T, where N(0) is
taken from electronic structure calculations (i.e.
N(0) is the DOS at the Fermi level). Thus, \lambda can
be considered as a measure of the enhancement of the
electronic heat due to electron - phonon interacton.  


> However, a question confused me for a long  time, 
> that is, there is  no unit for the electron pnonon 
> coupling parameter  lambda.

I suggest, the best way is reading a textbook or
related papers to be not confused.

Please do not forget provide your affiliation.

Bests,
Eyvaz.

--- Guoying Gao <gaoguoying at gmail.com> wrote:

> Dear pwscf users,
> 
>          I have done electron-phonon coupling
> calculations for a
> period. However, a question confused me for a long
> time, that is,
> there is
> no unit for the electron pnonon coupling parameter
> lambda. Does anyone
> know the reason for this? Any help will be
> appreciated.
> 
> Merry Christmas!
> 
> Guoying
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> 


-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, and 
Condensed Matter Theory Group, Uppsala University, Sweden 
Eyvaz.Isaev at fysik.uu.se, eyvaz_isaev at yahoo.com


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