[Pw_forum] about the electron-phonon coefficients

[Paolo Giannozzi]

On Jun 2, 2012, at 22:26 , 李晓东 wrote:

> In the appendix of the user guide (...) the electron-phonon
> coefficient has a factor (1/M)^0.5. This is calculated in the ph.x  
> program.
> Is the M the total mass of the unit cell, or reduced mass, or  
> averaged mass?


I wrote that appendix a lot of time ago and don't remember any longer
what M is (and don't want to know). My guess is that that the formula
is valid for simple metals with one type of atoms and M is the atom
mass. For more than one type of atoms, the formula should be
generalized (but the code should work correctly)

P.
---
Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222