ERROR in rs_pw_transfer during cell optimization

[Matthias Krack]

Dear Andrzej,

please keep in mind that the Mg-q10 pseudopotential is very hard. It
requires at least a cutoff of 600 Ry (or even more) with GPW in order
to obtain decent forces. Just check your electron count (look for
"Total charge density" in the CP2K output file). It should be correct
to about 1.0E-6. Thus for pseudopotentials as hard as Mg-q10 GAPW
might be a more convenient choice.

Best regards,

Matthias

On Mar 5, 11:36 am, Andrzej <kwa... at o2.pl> wrote:
> On Mar 4, 5:33 pm, Teodoro Laino <teodor... at gmail.com> wrote:
>
> > Andrzej,
>
> > therefore you won't get anything meaningful even without the above error
> > message.
> > Why don't you try with plain GPW?
>
> Thank you very much for a response.
> Why I decided to use all electron/GAPW,
> I would prefer to use pseudopotentials and GPW, but this approach led
> me to wrong results during geometry optimization.
> Here are a summary of my tests. All files I have loaded as
> geo_opt_tests_andrzej.tar.gz
>
> I used three approaches during crystal structure optimization
> (GEO_OPT):
> 1. all-electron/GAPW
> - results seems to be correct, here is the optimized structure:
> i =       20, E =      -254.4397076770
>   H         0.0000408810        2.4704770383       14.8136893102
>   H        -0.9689532669        3.0298933452        1.4034103139
>   H         2.1394587515        1.2352435453        0.1863173192
>   H         3.1084573793        0.6758216607       13.5966012290
>   H         0.0000004580        1.3516209597        1.4034332796
>   H         2.1394994962        2.3541034972       13.5965784978
>   H         0.9689524974        3.0298923370        1.4034718821
>   H         1.1705433143        0.6758226686       13.5965389830
>   B         0.0000057953        2.4704748301        1.0102779165
>   B         2.1394940538        1.2352442572       13.9897224598
>  Mg         0.0000006098        0.0000060417        0.0001054861
>
> and Mullikan charges:
>     9  B    -0.182266
>    10  B    -0.182275
>    11  Mg    0.384598
> Due to crystal symmetry, Mg atom should be at 0.0 0.0 0.0 and B atoms
> should be equivalent. It seems, that the program preserves all these
> features during the optimization.
>
> 2. pseudopotential: GTH-BLYP  // GAPW
> Symmetry seems also to be preserves, BUT the optimization goes in
> wrong direction. here is an energy listing:
>  i =        1, E =       -73.5175896722
>  i =        2, E =       -73.5181501663
>  i =        3, E =       -73.5169493546
>  i =        4, E =       -73.5146991276
>  i =        5, E =       -73.5120392333
>  i =        6, E =       -73.5092432038
>  i =        7, E =       -73.5064694489
>  i =        8, E =       -73.5037695513
>  i =        9, E =       -73.5011718324
>  i =       10, E =       -73.4986892533
> ...................................................
>  i =       50, E =       -73.5064816396
>  i =       51, E =       -73.5069568554
>  i =       52, E =       -73.5067869799
>  i =       53, E =       -73.5065578295
>  i =       54, E =       -73.5066356661
>  i =       55, E =       -73.5066449967
>  i =       56, E =       -73.5066449962 (final)
>
> 3. pseudopotentials: GTH-BLYP// GPW
> total mess in the results, symmetry is destroyed at once, here is an
> example of a structire at one of the optimization step:
>  i =      315, E =       -73.6283687957
>   H        -0.0033299605        2.4685447504       14.9168795057
>   H        -0.9730619996        3.0348140179        1.4858979291
>   H         2.1319315210        1.2308569967        0.1017540811
>   H         3.1129620505        0.6785024920       13.5228836249
>   H         0.0022477584        1.3454147948        1.4856679690
>   H         2.1439900361        2.3566698080       13.5228376561
>   H         0.9557248302        3.0221676817        1.5307358159
>   H         1.1633693810        0.6717413040       13.5297681616
>   B        -0.0065932634        2.4665767592        1.1133874591
>   B         2.1349713767        1.2326496289       13.8992265268
>  Mg        -0.1065214033       -0.0618890343        0.0417902798
>
> Mg is far from 0 0 0
> and charges:
>      9  B     0.041713
>     10  B    -0.057872
>     11  Mg   -0.258309
> show that B atoms are lo longer equivalent.
> Energy is oscillating strongly:
> i =      289, E =       -73.6282904477
>  i =      290, E =       -73.4773966228
>  i =      291, E =       -73.6282970478
>  i =      292, E =       -73.4774074691
>  i =      293, E =       -73.6283035434
>  i =      294, E =       -73.4774181459
>  i =      295, E =       -73.6283099418
>
> Of course, I could use CG and force convergence, and end up in an
> artificial structure with broken symmetry, but it can't be a solution.
>
> Playing with cutoff, basis sets and pseudopotentials I got results
> where Mg atom wandered even more in the cell.
> Only very large cut-offs can reduce (but not remove) these
> oscillations.
>
> To sum up, I was able to get results which seem reasonable only when
> all electron/GAPW was applied.
> What should I do then to get correct results with pseudopotential/GPW?
>
> regards
> Andrzej