[Pw_forum] dE0s is positive which should never happen

[Nicholas Edward Miller]

Hi Guntram,

Without really looking at the rest of the setup, I noticed you specify
'nat=196', but actually claim to have 215 atoms in the system.

-Nick

Quoting Guntram Schmidt <guntram.schmidt at chemie.uni-halle.de>:

> Dear All,
>
> I tried to optimize a crystal structure of a molecular compound and get
> this strange error. Is there something I've forgotten in the input file?
> I've chosen a small ecutwfc to make some "preoptimization" - is it okay
> to do so (I'm still not able to converge the cutoffs - see my other post)?
>
> &control
>    calculation = 'relax'
>    restart_mode='from_scratch',
>    prefix='i2t0480',
>    tstress = .true.
>    tprnfor = .true.
>    pseudo_dir = '/gpfs/home/aasfu/espresso-4.3.1/pseudo/',
>    outdir='/gpfs/home/aasfu/tmp/'
>    verbosity = 'high'
> /
> &system
>  ibrav = 14,
>  A = 8.2555,
>  B = 17.0986,
>  C = 16.3082,
>  cosAB = 0,
>  cosAC = -.4968073528,
>  cosBC = 0,
>  nat = 196,
>  ntyp = 5,
>  occupations = 'fixed',
>  ecutwfc = 20,
>  ecutrho = 80,
>  input_dft = 'vdW-DF'
> /
> &electrons
>     conv_thr        = 1.0d-5
>     electron_maxstep= 1000
> /
> &ions
> /
>
> ATOMIC_SPECIES
>  P 39.974 P.rpb-nc.UPF
>  O 15.999 O.rpb-nc.UPF
>  N 14.007 N.rpb-nc.UPF
>  C 12.011 C.rpb-nc.UPF
>  H 1.0079 H.rpb-nc.UPF
>
>
> ATOMIC_POSITIONS angstrom
>  H      -4.163902    3.036540    7.286078 1 1 1
>  C      -3.730208    5.027159    7.959787 1 1 1
>  H      -2.669409    4.951703    7.725352 1 1 1
>  C      -4.231111    6.183196    8.511764 1 1 1
>  H      -3.568842    7.024960    8.708593 1 1 1
> and 210 more atoms...
>
>
>
> The output says after 41 cycles of geometry optimizations in the
> subroutine stress:
>
>
>
>    0:     number of scf cycles    =  30
>    0:     number of bfgs steps    =  28
>    0:
>    0:     energy   old            =   -1592.2501932245 Ry
>    0:     energy   new            =   -1547.5620256423 Ry
>    0:
>    0:     CASE: energy  _new > energy  _old
>    0:
>    0:
>    0:
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>    0:     from bfgs : error #         1
>    0:     dE0s is positive which should never happen
>    0:
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>    0:
>    0:     stopping ...
>
> The strange thing is, that the energy was not -1592... before at all:
> grep '!' i2t0480.xyz.relax.20.rpb-nc.UPF.out
>    0:!    total energy              =   -1542.41391161 Ry
>    0:!    total energy              =   -1544.87249615 Ry
>    0:!    total energy              =   -1546.30689086 Ry
>    0:!    total energy              =   -1546.89859418 Ry
>    0:!    total energy              =   -1547.07908001 Ry
>    0:!    total energy              =   -1547.12438175 Ry
>    0:!    total energy              =   -1547.16304879 Ry
>    0:!    total energy              =   -1547.21850898 Ry
>    0:!    total energy              =   -1547.26799568 Ry
>    0:!    total energy              =   -1547.31147437 Ry
>    0:!    total energy              =   -1547.33202922 Ry
>    0:!    total energy              =   -1547.35963149 Ry
>    0:!    total energy              =   -1547.36650754 Ry
>    0:!    total energy              =   -1547.38045447 Ry
>    0:!    total energy              =   -1547.38597654 Ry
>    0:!    total energy              =   -1547.39351928 Ry
>    0:!    total energy              =   -1547.40184806 Ry
>    0:!    total energy              =   -1547.41383843 Ry
>    0:!    total energy              =   -1547.43030750 Ry
>    0:!    total energy              =   -1547.45110560 Ry
>    0:!    total energy              =   -1547.47294386 Ry
>    0:!    total energy              =   -1547.48424959 Ry
>    0:!    total energy              =   -1547.48774725 Ry
>    0:!    total energy              =   -1547.49458349 Ry
>    0:!    total energy              =   -1547.50098365 Ry
>    0:!    total energy              =   -1547.50487139 Ry
>    0:!    total energy              =   -1547.50802242 Ry
>    0:!    total energy              =   -1547.51133404 Ry
>    0:!    total energy              =   -1547.51564694 Ry
>    0:!    total energy              =   -1547.52054790 Ry
>    0:!    total energy              =   -1547.52614229 Ry
>    0:!    total energy              =   -1547.53597920 Ry
>    0:!    total energy              =   -1547.54614655 Ry
>    0:!    total energy              =   -1547.55021920 Ry
>    0:!    total energy              =   -1547.55191818 Ry
>    0:!    total energy              =   -1547.55360256 Ry
>    0:!    total energy              =   -1547.55527582 Ry
>    0:!    total energy              =   -1547.55697509 Ry
>    0:!    total energy              =   -1547.55871207 Ry
>    0:!    total energy              =   -1547.56042619 Ry
>    0:!    total energy              =   -1547.56202564 Ry
>
>
> Thanks a lot for help,
> Guntram
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