[Pw_forum] Error in routine sym_rho_init_shell "lone vector" with fixed FFT dimension

[Paolo Giannozzi]

On Thu, 2014-02-06 at 12:58 +0100, Thomas Gruber wrote:

> I attached 2 inputs files. One with smaller volume works and one with 
> greater volume with the corresponding *.out file, which works not. Since 
> I have already done phonon calculations for 5 different volumes, I don't 
> want to change the FFT dimension. I fixed it to 48 48 200 and the not 
> fixed FFT dimension would be 50 50 200.
> Any suggestions?

it works if you reduce by a little bit "ecutrho" from its default value
4*ecutwfc. The problem is that if you keep the FFT grid fixed, you may
"miss" a few G-vectors. The algorithm that divides G-vectors into shells
of vectors transforming into each other cannot work if a shell is
incomplete. Alternatively: remove symmetry, since such algorithm is 
used only for symmetrization of the charge density. I have no better
ideas right now: finding an algorithm that is guaranteed to work if 
the FFT grid is not sufficient to accommodate the G-vector sphere 
up to G^2< ecutrho may require a serious effort

Paolo

> Regards,
> 
> Thomas Gruber
> 
> On 02/06/2014 12:00 PM, pw_forum-request at pwscf.org wrote:
> > Message: 11
> > Date: Wed, 05 Feb 2014 19:45:00 +0100
> > From: Paolo Giannozzi<paolo.giannozzi at uniud.it>
> > Subject: Re: [Pw_forum] Error in routine sym_rho_init_shell "lone
> > 	vector" with fixed FFT dimension
> > To: PWSCF Forum<pw_forum at pwscf.org>
> > Message-ID:<1391625900.28572.9.camel at pania.fastwebnet.it>
> > Content-Type: text/plain; charset="UTF-8"
> >
> > Very strange. The error signals a failure in the algorithm
> > that finds shells of G-vectors that transform into each other
> > under symmetry operations. It might however be due to too small
> > FFT dimensions, maybe. It is hard to figure out what happens
> > without an input file.
> >
> > P.
> >
> > On Wed, 2014-02-05 at 15:49 +0100, Thomas Gruber wrote:
> >> >  Dear all,
> >> >  
> >> >  I try to determine the heat capacity at constant pressure and calculate
> >> >  the phonon DOS at different volumes. Since I get jumps in free energy
> >> >  when the FFT dimension change, I fix it to the one from the starting
> >> >  volume. But for on of my systems everything works fine up to 4%
> >> >  isotropic increase of the cell axis and at 5%  I get the following error
> >> >  in the starting scf calculation:
> >> >     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> >> >         Error in routine sym_rho_init_shell (2):
> >> >         lone vector
> >> >     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> >> >  This error does not show up, when I do not fix the FFT dimension.
> >> >  Without fixing the FFT dimension the FFT dimension is different to the
> >> >  one I choose.
> >> >  Is there a way to keep my fixed FFT dimension and get rid of this error?
> >> >  
> >> >  Thanks in advise.
> >> >  
> > -- Paolo Giannozzi, Dept. Chemistry&Physics&Environment, Univ. Udine, 
> > via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax 
> > +39-0432-558222
> 
> 
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-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222