[Pw_forum] wrong representation in qe-6.0: Bad but working solution

[Lorenzo Paulatto]

I have a personalised version of the random_matrix routine that fills it
with normal-distributed numbers. This in theory should cause the
eigenvalues to be uniformly spaced. I have never uploaded it because I have
no proof that it works better than the usual one, but if someone wants to
try it in some difficult corner case, please contact me

-- 
Lorenzo Paulatto
Written on a virtual keyboard with real fingers

On 15 Nov 2016 2:07 p.m., "Antoine JAY" <antoine.jay at polytechnique.edu>
wrote:

> To avoid this error message and to be able to do the phonon calculation
> without modifying the file "random_matrix.f90", I slightly modified the
> last decimals of the input atomic positions and lattice parameters.
> This does not change significantly the the inter atomic forces which are
> still quite null (<10^-5 Ry/au) nor the stress tensor, but this noise is
> enough to separate non-degenerated modes.
>
> Antoine Jay
>
>
>
> Answering myself: later, for a specific k-point. Quick example showing the
> problem attached.
>
>
> Paolo
>
> On Tue, Nov 8, 2016 at 7:12 PM, Paolo Giannozzi <p.gianno... at gmail.com>
> wrote:
>
> > When does this happen? at the beginning of the phonon calculation or
> later?
> >
> > Paolo
> >
> > On Tue, Nov 8, 2016 at 1:22 PM, Antoine JAY <
> antoine.... at polytechnique.edu
> > > wrote:
> >
> >> Hello community & developers,
> >>
> >> Performing phonons on gamma-boron at 30 GPa (using GGA), I have this
> >> message:
> >>      from set_irr_sym_new : error #      2111
> >>      wrong representation
> >>
> >> I send down the atomic positions as I know from previous mail (Lorenzo
> >> Paulatto 2012-07-23) that you need some tests to find a reliable way to
> >> generate the initial random pseudo-dynamical matrix (random_matrix.f90).
> >> Lattice and atomic positions are already converged.
> >>
> >> Increasing the threshold 10^-6 to 10^-4 line 156 and 158  of
> >> set_irr_sym.f90
> >> does not solve this issue.
> >>
> >> Do you have any other suggestion?
> >>
> >> Thank you very much
> >>
> >> Antoine Jay
> >>
> >> &control
> >>     calculation = 'scf',
> >>     prefix      = '$name.$Pression',
> >>     tstress     = .true.,
> >>     tprnfor     = .true.,
> >>     pseudo_dir  = '$PSEUDO_DIR/',
> >>     outdir      = '$TMP_DIR/',
> >>     etot_conv_thr=1.0d-6,
> >>     forc_conv_thr=1.0d-4,
> >>     nstep=1400,
> >>     wf_collect=.true.
> >> /
> >> &system
> >>     ibrav =8
> >>     celldm(1) = 9.213227
> >>     celldm(2) = 1.113897
> >>     celldm(3) = 1.365520
> >>     nat=  28,
> >>     ntyp= 5,
> >>     ecutwfc =80,
> >> /
> >>  &electrons
> >>     diagonalization='david'
> >>     mixing_beta = 0.7
> >>     conv_thr =  1.0d-13
> >>
>
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