[Thermo_pw-forum] about anharmonic properties - output files

[Andrea Dal Corso]

On Fri, 2015-07-10 at 06:05 +0000, Uma Mahendra Kumar K wrote:
> Dear Prof Andrea Dal Corso,
> 
>                       I am new user of thermo_pw.  In the anhrormic properties, the results are printed in to two files
> one with name  output_anhar.dat and another one with output_anhar.dat.aux_ph.
> 

In output_anhar.dat the volume as a function of T (and then the thermal
expansion) is calculated using a vibrational free energy computed from
the phonon dos. output_anhar.dat.aux_ph contains the same quantities but
the free energy is calculated doing the sum over the phonon frequencies
without using the phonon dos.

In the lib directories there are two modules to calculate the
vibrational free energies:

phdos_module.f90
ph_freq_module.f90

The quantities in output_anhar.dat are calculated using the routines of
phdos_module, those output_anhar.dat.aux_ph using the routines of
ph_freq_module. The two are almost always the same provided that you use
a sufficient number of q points to sample the phonon frequencies.

Andrea


> Some how i missed your explanation about these two out put files.
> If possible please clarify me.
> 
> Mahendra
> Dept of Physics
> VIT university
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-- 
Andrea Dal Corso                    Tel. 0039-040-3787428
SISSA, Via Bonomea 265              Fax. 0039-040-3787249
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