[Pw_forum] force does not convergence in vc-relax (too many g-vectors)
Paolo Giannozzi
paolo.giannozzi at uniud.it
Wed Jan 21 12:17:34 CET 2015
On Mon, 2015-01-19 at 07:52 +0000, samira adimi wrote:
> I am trying to optimize alanate structure so after finding
> experimental cell parameters reported in some papers, I've used this
> values for a scf calculation and the total force was large. so I did
> vc-relax
you should do a structural relaxation at fixed cell ('relax') before
assuming that your cell parameters are not good. In fact in the data
you sent to me the initial and starting cell volumes are almost exactly
the same.
> but the force doesn't converge
note that if you fix some atoms or some components (and you did)
you may never get zero forces
> and after doing all the 50 step there is an error
> Error in routine ggen (124238):
> too many g-vectors
definitely, this shouldn't happen. Unfortunately it is a little bit hard
to figure out why this happens at the end of a very long run.
Paolo
> stopping ...
> I changed atomic positions and celldm to the numbers reported in another paper (which of course wasn't so much different), changed cell_dofree from 'ALL' to 'xyz' and changed number of steps to 100 and mixing_beta from 0.7 to 0.4 and I wonder why it is so!? force convergence threshold is default (10-3) but it didn't get close to it at all .
> Total force = 13.871671 Total SCF correction = 0.000894
> Total force = 0.197519 Total SCF correction = 0.000740
> Total force = 0.157196 Total SCF correction = 0.000621
> Total force = 0.115999 Total SCF correction = 0.000573
> Total force = 0.053391 Total SCF correction = 0.000327
> Total force = 0.040797 Total SCF correction = 0.000163
> Total force = 0.032710 Total SCF correction = 0.000225
> Total force = 0.029627 Total SCF correction = 0.000465
> Total force = 0.033331 Total SCF correction = 0.000301
> Total force = 0.035811 Total SCF correction = 0.000336
> Total force = 0.030198 Total SCF correction = 0.000162
> Total force = 0.022481 Total SCF correction = 0.000325
> Total force = 0.021899 Total SCF correction = 0.000137
> Total force = 0.022532 Total SCF correction = 0.000145
> Total force = 0.023763 Total SCF correction = 0.000080
> Total force = 0.025062 Total SCF correction = 0.000313
> Total force = 0.027075 Total SCF correction = 0.000213
> Total force = 0.032028 Total SCF correction = 0.000199
> Total force = 0.042803 Total SCF correction = 0.000254
> Total force = 0.058438 Total SCF correction = 0.000924
> Total force = 0.062056 Total SCF correction = 0.000269
> Total force = 0.063618 Total SCF correction = 0.000518
> Total force = 0.063175 Total SCF correction = 0.000544
> Total force = 0.073902 Total SCF correction = 0.000205
> Total force = 0.058493 Total SCF correction = 0.000251
> Total force = 0.052185 Total SCF correction = 0.000145
> Total force = 0.045162 Total SCF correction = 0.000246
> Total force = 0.046682 Total SCF correction = 0.000544
> Total force = 0.046137 Total SCF correction = 0.000237
> Total force = 0.045776 Total SCF correction = 0.000171
> Total force = 0.047833 Total SCF correction = 0.000445
> Total force = 0.047631 Total SCF correction = 0.000568
> Total force = 0.043484 Total SCF correction = 0.000084
> Total force = 0.037547 Total SCF correction = 0.000079
> Total force = 0.035930 Total SCF correction = 0.000198
> Total force = 0.037417 Total SCF correction = 0.000071
> Total force = 0.039621 Total SCF correction = 0.000122
> Total force = 0.041066 Total SCF correction = 0.000270
> Total force = 0.040720 Total SCF correction = 0.000494
> Total force = 0.037947 Total SCF correction = 0.000380
> Total force = 0.036433 Total SCF correction = 0.000483
> Total force = 0.037235 Total SCF correction = 0.000273
> Total force = 0.039574 Total SCF correction = 0.000137
> Total force = 0.042889 Total SCF correction = 0.000314
> Total force = 0.044080 Total SCF correction = 0.000545
> Total force = 0.044996 Total SCF correction = 0.000725
> Total force = 0.047969 Total SCF correction = 0.000268
> Total force = 0.054774 Total SCF correction = 0.000719
> Total force = 0.063602 Total SCF correction = 0.000861
> Total force = 0.074294 Total SCF correction = 0.001115
> Total force = 0.089046 Total SCF correction = 0.000614
> Total force = 0.126567 Total SCF correction = 0.000428
> Total force = 0.087063 Total SCF correction = 0.000251
> Total force = 0.060772 Total SCF correction = 0.000359
> Total force = 0.061800 Total SCF correction = 0.000717
> Total force = 0.066324 Total SCF correction = 0.000865
> Total force = 0.067172 Total SCF correction = 0.000806
> Total force = 0.049104 Total SCF correction = 0.000336
> Total force = 0.045172 Total SCF correction = 0.000227
> Total force = 0.042539 Total SCF correction = 0.000168
> Total force = 0.038010 Total SCF correction = 0.000382
> Total force = 0.031380 Total SCF correction = 0.000569
> Total force = 0.025136 Total SCF correction = 0.000272
> Total force = 0.025415 Total SCF correction = 0.000269
> Total force = 0.024962 Total SCF correction = 0.000336
> Total force = 0.026042 Total SCF correction = 0.000358
> Total force = 0.028929 Total SCF correction = 0.000430
>
> Although the total force is much less than the start point, the
> structure get worst and there is connection between two potassium
> atoms, which is nonsense here. and Too many g-vectors?! I don't know
> why and where these errors come from!
>
> I have attached both input and output file.
> Thanks in advance.
> Best regards,
> Samira Adimi
>
> P.S: Sorry for my bad english
>
>
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--
Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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