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

[Antoine JAY]

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
>>