[Pw_forum] cell_factor ignored in vc-relax

[Marco Di Gennaro]

Dear users,

I am running a vc-relax calculation on Si.
I need to impose the cell vectors coordinates (bravais lattice is not enough),
therefore I set ibrav = 0 and the coordinates explicitly.
Even though the cell_factor variable is imposed, I get a suspicious message:  "Warning: card     CELL_FACTOR  = 2 ignored"
In some cases, the calculation goes through and the cell evolves correctly (so not a big deal, just a warning).
In other cases I get an error such as:
" Not enough space allocated for radial FFT: try restarting with a larger cell_factor."
but now changing the cell_factor is of no help!!
I have tried upper/lower case, insert a supplementary slash sign before "ATOMIC SPECIES" and so on. Nothing worked.

Thanks in advance.
Please find below the input file (for the crashing case):

&CONTROL
    calculation  = 'vc-relax'
    etot_conv_thr = 1.0D-4
    forc_conv_thr = 1.0D-3
    outdir       = './out/'
    pseudo_dir   = '/users/mdigenna/pspfiles/QE/SSSP_eff_PBE'
    restart_mode = 'from_scratch'
    verbosity    =  'high'
    wf_collect   =  .true
/
&SYSTEM
    degauss      =  0.001
    ecutrho      =  240
    ecutwfc      =  20
    nat          =  2
    ntyp         =  1
    occupations  =  smearing
    smearing     =  m-v
    nbnd         =  10
    ibrav        =  0
/
&ELECTRONS
    conv_thr     = 1.e-6
/
&ions/
&cell/
    cell_factor  = 2
ATOMIC_SPECIES
    Si     28.0855 Si.pbe-n-rrkjus_psl.1.0.0.UPF
ATOMIC_POSITIONS angstrom
Si   1.65012877  3.40734966  5.34651599
Si   0.54892697  1.46693091  0.09970006
K_POINTS automatic
1 1 1 0 0 0
CELL_PARAMETERS angstrom
  2.42495529e+00   -1.70462702e-03   -1.07846112e-03
  -3.48138289e-03   5.35177562e+00   1.08773135e-02
  -2.51259083e-03   1.16376387e-02   5.98103881e+00


Marco Di Gennaro, Dr.
Nccr MARVEL - University of Basel
Phone +41 61 267 3846
Klingelbergstrasse 80, Office 5.10

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