# [Pw_forum] phonon calculation.

Eyvaz Isaev eyvaz_isaev at yahoo.com
Mon Feb 25 15:57:02 CET 2008

Dear Yanling,

Please respect the Netiquette accepted in this forum

--- Li yan-ling <ylli at theory.issp.ac.cn> wrote:
> I have two questions.
> 1. I don't know how to plot the a2F(omega) vs. omega
> function curve?

Use gnuplot or xmgrace to plot it. How to do it ask
your experienced friend. It is not a subject for this

If you have done everything correctly you have
a2F.dos.1 (2,3, ..., 10,  by default) files.  As you
frequency in Ry (find how to convert it to cm^{-1} or
THz), then a2F_total. Next three columns are mode
projected a2F (1 atom => 3 modes => 3 columns).
Numbers from 1 to 10 specify smearing widths used in
\gamma_{nk} calculations (from 0.01 to 0.10 by
default).
So, you can see how a2F is affected by this smearing
parameter through  a2F.dos.1 .... a2F.dos.10

> 2. I check the output file 'dyna2F'. It consists of
> all modes's a2F(omega), I think. But I can't
>understand its  meaning. In general, a2F
> vs. omega is a 2D ( two dimentional) curve. I want
> to know how to  transform it to the 2D form in order
>to ploting the  a2F(omega) as the function of omega
>curve?
>   Any answers or suggestions are welcome.

Actually, I do not think that you need to plot dyna2F
file. Instead use gam.lines to plot \gamma_{nk} along
high symmetry directions (numbers in the first column
are indexes for q-vectors along these directions) you
have chosen and in dependent on smearing width.

You can plot them, again, using gnuplot or xmgrace
(http://plasma-gate.weizmann.ac.il/Grace/).

Bests,
Eyvaz.

--- Li yan-ling <ylli at theory.issp.ac.cn> wrote:

> I have two questions.
> 1. I don't know how to plot the a2F(omega) vs. omega
> function curve?

Use gnuplot or xmgrace to plot it. How to do it ask
your experienced friend. It is not a subject for this

If you have done everything correctly you have
a2F.dos.1 (2,3, ..., 10,  by default) files.  As you
frequency in Ry (find how to convert it to cm^{-1} or
THz), then a2F_total. Next three columns are mode
projected a2F (1 atom => 3 modes => 3 columns).
Numbers from 1 to 10 specify smearing widths used in
\gamma_{nk} calculations (from 0.01 to 0.10 by
default).
So, you can see how a2F is affected by this smearing
parameter through  a2F.dos.1 .... a2F.dos.10

> 2. I check the output file 'dyna2F'. It consists of
> all modes's a2F(omega), I think. But I can't
>understand its  meaning. In general, a2F
> vs. omega is a 2D ( two dimentional) curve. I want
> to know how to  transform it to the 2D form in order
>to ploting the  a2F(omega) as the function of omega
>curve?
>   Any answers or suggestions are welcome.

Actually, I do not think that you need to plot dyna2F
file. Instead use gam.lines to plot \gamma_{nk} along
high symmetry directions you have chosen and in
dependent on smearing width.

You can plot them, again, using gnuplot or xmgrace
(www.

> Thanks a lot.
>
> Yanling Li
>
>
>
>
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> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>

-------------------------------------------------------------------
Prof. Eyvaz Isaev,
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia,