[Pw_forum] BFGS relaxation ignoring forc_conv_thr
Paolo Giannozzi
p.giannozzi at gmail.com
Wed Sep 20 14:03:01 CEST 2017
If you look carefully in the output, you will notice this:
WARNING: bfgs curvature condition failed, Theta= 0.815
Message from routine bfgs:
history already reset at previous step: stopping
This kind of problem arises when one is very close to convergence and forces
contain too much numerical noise for the minimization to be effective.
Not sure why it performs a further step.
Paolo
On Wed, Sep 20, 2017 at 9:56 AM, Leonid Kahle <leonid.kahle at epfl.ch> wrote:
> Dear all,
>
> A relaxation of a rather large system (Li21 Si3 P3 S24) is shown as
> converged even though the force convergence threshold is not reached. I
> will paste the final output below, and the full input and output are
> attached. I put a very low threshold 1D-15 to prove my point here, but also
> more sensible thresholds are ignored.
>
> As explained in the documentation, but also in this forum (
> http://qe-forge.org/pipermail/pw_forum/2004-November/076156.html )
> convergence of the relaxation is achieved when all the components of the
> force vector are smaller than forc_conv_thr (and energy criterion is met as
> well). In the example below this is obviously not the case, but bfgs is
> shown as converged without any warning.
>
> Can anyone help me find an explanation for this? I am using the parallel
> version of QE 6.1 compiled with intel compilers on an x86_64 architecture.
>
> Many thanks in advance,
>
> Leonid Kahle
>
> --
>
> Doctoral Assistant
> EPFL STI IMX THEOS
> ME-D2 1019 (Bâtiment ME)
> Station 9
> CH-1015 Lausanne (Switzerland)
>
>
> Forces acting on atoms (cartesian axes, Ry/au):
>
> atom 1 type 1 force = 0.00000940 0.00000005 0.00000759
> atom 2 type 1 force = 0.00003922 -0.00005066 -0.00003891
> atom 3 type 1 force = -0.00000527 -0.00001786 -0.00000047
> atom 4 type 1 force = 0.00000695 -0.00000525 -0.00000490
> atom 5 type 1 force = 0.00000837 0.00000136 0.00000695
> atom 6 type 1 force = -0.00000139 0.00000800 -0.00000768
> atom 7 type 1 force = -0.00000042 -0.00000074 -0.00000888
> atom 8 type 1 force = -0.00002354 -0.00001155 -0.00003861
> atom 9 type 1 force = 0.00001305 -0.00001546 0.00000555
> atom 10 type 1 force = -0.00001756 0.00002269 -0.00001184
> atom 11 type 1 force = -0.00000255 -0.00001734 0.00001741
> atom 12 type 1 force = 0.00001174 0.00001759 -0.00001735
> atom 13 type 1 force = -0.00000633 -0.00000979 0.00000484
> atom 14 type 1 force = -0.00001325 0.00001294 -0.00000493
> atom 15 type 1 force = 0.00000782 -0.00002956 -0.00000586
> atom 16 type 1 force = -0.00000317 0.00001363 0.00000878
> atom 17 type 1 force = -0.00002203 0.00000270 -0.00000480
> atom 18 type 1 force = -0.00000998 0.00000531 0.00001788
> atom 19 type 1 force = 0.00000060 -0.00000321 -0.00001756
> atom 20 type 1 force = -0.00000688 0.00002017 0.00000404
> atom 21 type 1 force = -0.00000129 -0.00000416 -0.00001532
> atom 22 type 2 force = -0.00000319 -0.00000167 0.00000395
> atom 23 type 2 force = 0.00001103 0.00001040 0.00000626
> atom 24 type 2 force = 0.00000396 -0.00000186 0.00000201
> atom 25 type 3 force = -0.00001044 0.00000478 -0.00000086
> atom 26 type 3 force = -0.00001291 0.00000415 -0.00000411
> atom 27 type 3 force = 0.00001756 -0.00000296 0.00000913
> atom 28 type 4 force = -0.00001578 0.00000879 0.00000423
> atom 29 type 4 force = -0.00001227 0.00000946 -0.00000839
> atom 30 type 4 force = 0.00001416 0.00001301 0.00001436
> atom 31 type 4 force = 0.00001660 -0.00000202 0.00000659
> atom 32 type 4 force = 0.00003452 -0.00001067 0.00001793
> atom 33 type 4 force = 0.00000938 -0.00001056 0.00000237
> atom 34 type 4 force = -0.00001496 -0.00000472 0.00000305
> atom 35 type 4 force = -0.00001625 -0.00000739 -0.00000918
> atom 36 type 4 force = 0.00001063 0.00001606 -0.00000310
> atom 37 type 4 force = -0.00000110 0.00000394 -0.00000268
> atom 38 type 4 force = -0.00000163 0.00000039 0.00000700
> atom 39 type 4 force = -0.00000066 -0.00000016 0.00000132
> atom 40 type 4 force = -0.00000813 0.00000603 0.00000016
> atom 41 type 4 force = -0.00001613 0.00000196 0.00000515
> atom 42 type 4 force = -0.00000014 0.00000820 -0.00000460
> atom 43 type 4 force = 0.00000091 0.00000952 0.00001063
> atom 44 type 4 force = 0.00000012 -0.00000246 0.00000554
> atom 45 type 4 force = 0.00000154 0.00000256 0.00001045
> atom 46 type 4 force = 0.00000846 0.00000608 -0.00000078
> atom 47 type 4 force = 0.00000508 -0.00000261 0.00001345
> atom 48 type 4 force = 0.00000340 0.00000050 0.00000619
> atom 49 type 4 force = 0.00000354 -0.00000332 0.00000588
> atom 50 type 4 force = -0.00000428 0.00000637 0.00000854
> atom 51 type 4 force = -0.00000650 -0.00000066 -0.00000641
>
> Total force = 0.000149 Total SCF correction = 0.000000
>
> bfgs converged in 4 scf cycles and 3 bfgs steps
> (criteria: energy < 1.0E-06 Ry, force < 1.0E-15 Ry/Bohr)
>
> End of BFGS Geometry Optimization
>
>
>
>
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--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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