[Pw_forum] EPC

Eyvaz Isaev eyvaz_isaev at yahoo.com
Tue Apr 29 22:29:42 CEST 2003

Dear Ma,

Thank you for your comments. Probably, my problem is
connected to the old code (concerning output files) I
am still using. I have commented the line reading
w2(nu), because I used output file dyn.qpoint to get
frequences which are given in THz.
But according to your message w2(nu) is in Ry**2.
Is there new output file for them (i.e. which file
contains w2(nu) in Ry**2 units)?

I tried some "degaussq" and good agreement with
\lambda averaged over the BZ was found for
degaussq=0.01, and for others they are quite
different. Sure, this looks a tricky and I am also not
sure about degaussq choice.

Besides, I am displeased very much getting featureless


--- ma Yanming <yanming_ma at hotmail.com> wrote:
> Dear Eyvaz
> >I have to note that there is some disagreement
> between
> >units. Emax is given in THz, later omega is
> multiplied
> >by 3289.828 in order to convert it to Ry which
> results
> >in zero alpha2F. When I tried to divide both "e"
> and
> >"omega" by 3289.828, I got \lambda \approx 0.19.
> I don't think there exist some mismatch between
> units in lambda.f
> Emax is in THz unit. w2(nu) is in Ry**2. So omega is
> in THz as we know.
> It doesn't make sense to divide "e" and "omega" by
> 3289.828 if e, omega, 
> and degaussq are in THz unit. 
> But one thing that I am not quite clear is how to
> choose degaussq and 
> ngaussq properly. If we choose the ones used in the
> EPC calculation, then 
> the results will be like ghost. If we can not choose
> those ones then this 
> will cause the problem that the choice for these
> values are not unique. For 
> the purpose of test, I tried to chose different
> degaussqs and ngaussqs to 
> get the Spectral function. The shape and smoothness
> of spectral function is 
> somehow different. This mean that at this moment
> PWSCF only can get the 
> estimated spectral function.  
> Best Wishes!
> Yanming Ma PhD
> Steacie Institute for Molecular Sciences,
> National Research Councils of Canada.
> 100 Sussex
> K1A 0R6
> ÏíÓÃÊÀ?çÉÏ×î?ó?Ä?ç×ÓÓÊ?þÏ?ͳ?? MSN Hotmail?£ 
> http://www.hotmail.com  
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