[CP2K-user] [CP2K:13207] CELL Optimization - Energy not decreasing
Jan Elsner
janel... at gmail.com
Thu Apr 30 18:04:56 UTC 2020
Dear Thomas,
I attach inputs and outputs with the modified settings. As before, using
VWN gives consistent forces. Using PW92 gives inconsistent forces (as
before) however now the forces for Atom 2 are fine, but way off for Atom 3.
I'm not sure why this would be the case.
Best,
Jan
On Thursday, April 30, 2020 at 5:14:33 PM UTC+1, tkuehne wrote:
>
> Dear Jan,
>
> thanks for putting this to our attention, the deviation looks indeed on
> the upper end.
> However, computing numerical derivatives is a bit tricky and has to be
> done with
> maximum accuracy, since relative deviations of small values are reported.
> So this may be an error, but can you please increase EPS_DEFAULT to 10E-16
> and EPS_SCF to 10E-7 and try this also with DX to 5.0E-4?
>
> Cheers,
> Thomas
>
> P.S. BTW, I did a similar test with the sole PADE XC functional, which is
> supposed
> to mimic PW92 LDA many years ago and it passed the test ...
>
> Am 30.04.2020 um 17:30 schrieb Jan Elsner <ja... at gmail.com
> <javascript:>>:
>
> Dear all,
>
> I thought I should post an update on this.
>
> It seems that there is a problem with using PW92 as the local correlation
> part of XC functional. When I use VWN instead, the analytical and numerical
> forces are equal. I attach input and output files for DEBUG runs on a
> single H20 molecule using optPBE in combination with PW92 and VWN. In the
> case of PW92, there is a mismatch between analytical and numerical forces.
>
> I note that the same applies for the some of the other functionals listed
> here: https://github.com/cp2k/cp2k/tree/master/data/xc_section (at least,
> I can confirm that optB88 and C09 also give a mismatch between numerical
> and analytical forces using the settings listed here).
>
> Best wishes,
>
> Jan
>
>
>
>
> On Friday, April 24, 2020 at 10:43:00 AM UTC+1, Jan Elsner wrote:
>>
>> Dear Juerg,
>>
>> Many thanks for the quick response! Unfortunately, decreasing EPS_SCF
>> (all the way to 1.0E-10) does not solve the problem.
>>
>> I have done a DEBUG run which results in the following error (see end of
>> attached file debug.out): *'Abort: A mismatch between the analytical and
>> the numerical stress tensor has been detected. Check the implementation of
>> the stress tensor'*. I'm not entirely sure how I should proceed from
>> here / what the problem is exactly - any insight would be very much
>> appreciated.
>>
>> If it helps shed some light on the problem, I also attach a figure
>> showing Total Energy, RMS Gradient and Cell Volume as a function of
>> optimization step (plotted from the original cell.out file I sent). The
>> optimiser seems to overshoot the minimum energy configuration.
>>
>> One other question which comes to mind is whether it's ok to use GTH-PBE
>> or GTH-PADE pseudopotentials with optPBE-vdW?
>>
>> Best wishes,
>>
>> Jan
>>
>>
>>
>>
>>
>> On Monday, April 20, 2020 at 10:20:34 AM UTC+1, jgh wrote:
>>>
>>> Hi
>>>
>>> I don't know how well a setup as this is tested. However, from
>>> your output I would guess the problem could be related to your
>>> SCF convergence. With the methods you are using you have to set
>>> the convergence criteria much tighter in order to get converged
>>> energy and forces. I would suggest to use at least 1.E-8.
>>>
>>> The ultimate test would be to do a DEBUG run in order to verify
>>> forces and stress tensor for the setting of options.
>>>
>>> regards
>>>
>>> Juerg Hutter
>>> --------------------------------------------------------------
>>> Juerg Hutter Phone : ++41 44 635 4491
>>> Institut für Chemie C FAX : ++41 44 635 6838
>>> Universität Zürich E-mail: h... at chem.uzh.ch
>>> Winterthurerstrasse 190
>>> CH-8057 Zürich, Switzerland
>>> ---------------------------------------------------------------
>>>
>>> -----c... at googlegroups.com wrote: -----
>>> To: "cp2k" <c... at googlegroups.com>
>>> From: "Jan Elsner"
>>> Sent by: c... at googlegroups.com
>>> Date: 04/18/2020 08:33PM
>>> Subject: [CP2K:13145] CELL Optimization - Energy not decreasing
>>>
>>> Dear all,
>>>
>>> I am trying to run a Cell Optimisation on a periodic molecular crystal
>>> (beta-resorcinol: C6H6O2, 4 molecules in unit cell) using K-points and BFGS
>>> as optimiser. I am using the vdW-DF-optPBE functional (
>>> https://github.com/cp2k/cp2k/commit/74ef05b96a46523a0daf7da04e75804420b5cd5e).
>>> After 83 optimisation steps, my system does converge to the required MOTION
>>> thresholds, however from step 7 onwards the total energy increases at every
>>> step i.e.:
>>>
>>> -------- Informations at step = 7 ------------
>>> Optimization Method = BFGS
>>> Total Energy = -280.1489665596
>>> Internal Pressure [bar] = -2667.4573178334
>>> Real energy change = 0.0001037473
>>> Predicted change in energy = -0.0001063956
>>> Scaling factor = 0.0000000000
>>> Step size = 0.0124910496
>>> Trust radius = 0.4724315332
>>> Decrease in energy = NO
>>> Used time = 60.978
>>>
>>> Convergence check :
>>> Max. step size = 0.0124910496
>>> Conv. limit for step size = 0.0010000000
>>> Convergence in step size = NO
>>> RMS step size = 0.0029192108
>>> Conv. limit for RMS step = 0.0010000000
>>> Convergence in RMS step = NO
>>> Max. gradient = 0.0034738629
>>> Conv. limit for gradients = 0.0001000000
>>> Conv. for gradients = NO
>>> RMS gradient = 0.0006857738
>>> Conv. limit for RMS grad. = 0.0001000000
>>> Conv. for gradients = NO
>>> Pressure Deviation [bar] = -2668.4705678334
>>> Pressure Tolerance [bar] = 200.0000000000
>>> Conv. for PRESSURE = NO
>>> ---------------------------------------------------
>>>
>>> The resulting cell-optimised structure is therefore not a minimum in
>>> energy. I've attached the input and output files. Some points which may (or
>>> may not) be relevant:
>>> I did not encounter this problem when using a different functional (PBE
>>> + D3 instead of optPBE-vdW as used here), but otherwise identical settings.
>>>
>>> I encountered the same issue (energy increasing at every step) using
>>> CUTOFF/REL_CUTOFF = 800/60
>>> I initially tried to converge CUTOFF and REL_CUTOFF as in the tutorial (
>>>
>>> https://www.cp2k.org/howto:converging_cutoff), however my single point
>>> calculations did not converge quite as nicely as in the tutorial - instead
>>> oscillating with an amplitude of order ~ e-4 Ha (I've attached a figure
>>> showing this). This is why I use such large CUTOFF/REL_CUTOFF values. I
>>> note that this was also the case when I ran PBE + D3 calculations, however
>>> in the latter case my cell optimisation did work.
>>>
>>> Any input would be greatly appreciated.
>>>
>>> Best wishes,
>>>
>>> Jan
>>>
>>>
>>>
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>>> .
>>>
>>>
>>> [attachment "cell.inp" removed by Jürg Hutter/at/UZH]
>>> [attachment "cell.out" removed by Jürg Hutter/at/UZH]
>>> [attachment "E_vs_cutoff.png" removed by Jürg Hutter/at/UZH]
>>> [attachment "subsys.include" removed by Jürg Hutter/at/UZH]
>>>
>>
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> .
> <pw92.inp><pw92.out><vwn.inp><vwn.out>
>
>
>
>
> ==============================
> Thomas D. Kühne
> Dynamics of Condensed Matter
> Chair of Theoretical Chemistry
> University of Paderborn
> Warburger Str. 100
> D-33098 Paderborn
> Germany
> td... at mail.upb.de <javascript:>
> +49/(0)5251/60-5726
>
>
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