[Pw_forum] phonon linewidth

[Paolo Giannozzi]

On Thu, 2014-04-17 at 17:18 -0700, Hongliang Xin wrote:

>  What bothers me a little bit is the definition of phonon linewidth
> (Eq. 2) in PHonon package users' guide. I did not see any difference
> with the definition of actual vibrational dephasing rate. I tried to
> go through the code elphon.f90, but did not convince myself this 2pi
> factor is in the calculation or not.

once upon a time I verified that all factors were consistent with the
formulas now reported in the user guide. I remember that it took me
some time before I realized that "a factor M^−1/2 is hidden in the
definition of normal modes as used in the code" (line after Eq.5). 
Not sure about the 2*pi factor, but it might be hidden into 
nu = 2*pi*omega

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