[Pw_forum] Phonon DOS

[Eyvaz Isaev]

Yes, I think so.  You can try  epsil=.true. for the
\Gamma point and recalculate phonons at the \Gamma
point only. Hopefully nothing should be changed for
frequencies (there should be additionall lines in the
dynamical matrix file) if you have metallic system.

Nevertheless an origin of the message is not clear.
May be due to smearing you have a little gap. The best
test is the electronic DOS calculations.  

Regards,
Eyvaz.

--- Subhradip Ghosh <subhra at physics.rutgers.edu>
wrote:
> On Fri, 30 May 2003, Eyvaz Isaev wrote:
> 
> Thanks a lot. However, in the old version I
> mentioned ngauss and degauss
> always keeping in mind that it's a metal. That's why
> I am puzzled a bit.
> What I understand from your message is that even
> though the error message
> remains there is nothing wrong in the calculations
> and I can trust my
> results.
> 
> Regards,
> 
> Subhradip
> 
> > Dear Subhradip,
> >
> > I assume it will not affect for your calculations
> if
> > you have a metallic system.
> > But it is very important for polar semiconductors
> > where
> > splitting of optical modes at the \Gamma point is
> not
> > possible without applying electric field via
> > calculation of macroscopic dielectric constant.
> > The error means that electric field is not
> included.
> >
> > A reason for the message might be you did not
> > mention degauss and ngauss parameters for SCF
> > calculations (for old versions). For the new
> version
> > there should be three paremeters:  occupations,
> > smearing, degauss (in "system" section). If there
> are
> > not, your system is assumed to be semiconductor
> type.
> >
> > Besides, I remember my promise. I will do that
> soon.
> >
> > Regards,
> > Eyvaz.
> > Theoretical Physics Department
> > Moscow Steel and Alloys Institute
> >
> > --- Subhradip Ghosh <subhra at physics.rutgers.edu>
> > wrote:
> > > Hi,
> > >
> > > I am trying to compute Phonon DOS using the code
> > > matdyn.f90. I found that
> > > it worked for an insulator but in my case the
> system
> > > is metallic and while
> > > I ran the code there is some output generated
> > > alongwith an error message
> > >
> > >
> >
>
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> > >      from matdyn : error #        -1
> > >      non-analytic term for q=0 missing !
> > >
> > >
> >
>
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> > > I traced it back to the code and found that this
> > > error message pops up in
> > > case we have no dielectric tensor(probably)
> written
> > > in the real-space
> > > force constant
> > > file. There is a logical switch in the force
> > > constant file which comes out
> > > to be F in my case and therefore there are no
> > > entries of the variable
> > > epsil. I have no idea what the remedy is? Is it
> a
> > > serious error or should
> > > I ignore it?
> > >
> > > Thanks in advance,
> > >
> > > Subhradip
> > >
> > > PS: My system is not a simple metal, rather a
> > > metallic alloy.
> > >
> > >
> >
>
############################################################################
> > > 		     Dr	Subhradip Ghosh
> > > 		     Post Doctoral Fellow
> > > 		Condensed matter theory group
> > > 	        Department of Physics and Astronomy
> > >
> >
>
############################################################################
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> >
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> > > 136 Frelinghuysen Road                      |NJ
> > > 08904
> > > Piscataway, NJ 08854-8019                   |USA
> > > USA                                         |
> > > Email address: subhra at physics.rutgers.edu,
> > > |Telephone # :(732)4489266
> > >                subhradip at yahoo.com          |
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>
############################################################################
> 		     Dr	Subhradip Ghosh
> 		     Post Doctoral Fellow
> 		Condensed matter theory group
> 	        Department of Physics and Astronomy
>
############################################################################
> Office:                                     |
> Residence:
>
--------------------------------------------|-------------------------------
> Serin E255                                  |132,
> South Adelaide Avenue
> Department of Physics and Astronomy        
> |Apartment# 2A
> Rutgers, The State University of New Jersey
> |Highland Park
> 136 Frelinghuysen Road                      |NJ
> 08904
> Piscataway, NJ 08854-8019                   |USA
> USA                                         |
> Email address: subhra at physics.rutgers.edu, 
> |Telephone # :(732)4489266
>                subhradip at yahoo.com          |
> Telephone #  : (732)445-4604                |
>
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