[CP2K-user] [CP2K:19020] Re: TiO2 slab not converging

Léon Luntadila Lufungula Leon.luntadilalufungula at uantwerpen.be
Wed Jun 28 14:10:15 UTC 2023


Hi Matthias,

Thanks a lot for the tip! The output when using the pre-compiled binary 
shows that some atoms are indeed too close together, which is probably the 
cause of the bad convergence. Is there an easy way to fix this? 

I made the slabs with ASE so I'm quite surprised that it did not make the 
slabs correctly. Here is the script I used to make them with ASE, perhaps 
you can see where I made a mistake, resulting in the faulty CIF files...

from ase.io import read, write
from ase.visualize import view
from ase.build.surfaces_with_termination import surfaces_with_termination
from ase.build.tools import sort

ana = read('anatase_opt_tzvp.pdb')

for N in range(2,13):
    s = surfaces_with_termination(ana, (1,0,1), N, vacuum=20, 
termination='O')
    s = s[1]
    s = s.repeat((1,3,1))
    s = sort(s, tags=s.positions[:, 2])
    name = f'a101-{N}-layer'
    write(f'{name}.cif', s)

Léon

On Wednesday, 28 June 2023 at 15:58:25 UTC+2 Krack Matthias wrote:

> Hi Léon 
>
>  
>
> You are using CP2K version 8.2. Newer CP2K versions perform a distance 
> check for CP2K/Quickstep by default (see also this input keyword 
> <https://manual.cp2k.org/cp2k-2023_1-branch/CP2K_INPUT/FORCE_EVAL/SUBSYS/PRINT/INTERATOMIC_DISTANCES.html#CHECK_INTERATOMIC_DISTANCES>) 
> when the system is smaller than 2000 atoms and prints a warning if a small 
> distance is found. 
>
> You can download a pre-compiled binary of CP2K 2023.1 here 
> <https://github.com/cp2k/cp2k/releases/download/v2023.1/cp2k-2023.1-Linux-gnu-x86_64.ssmp>, 
> which is sufficient for that initial check.
>
>  
>
> HTH
>
>  
>
> Matthias
>
>  
>
> *From: *cp... at googlegroups.com <cp... at googlegroups.com> on behalf of Léon 
> Luntadila Lufungula <Leon.luntad... at uantwerpen.be>
> *Date: *Wednesday, 28 June 2023 at 15:46
> *To: *cp2k <cp... at googlegroups.com>
> *Subject: *Re: [CP2K:19017] Re: TiO2 slab not converging
>
> Hi Matthias,
>
>  
>
> Thanks for you reply!
>
>  
>
> I looked at my CIF file in various visualization software and it looked 
> okay there. Is there a way to check this via CP2K to be sure?
>
> I also have some preliminary results of some ongoing calculations with 
> DIIS/FULL_ALL and DIIS/FULL_SINGLE_INVERSE and these seem to be a bit 
> faster than CG but reaching convergence is still a big issue (see 
> attachments).
>
> Best,
> Léon
>
>  
>
> On Wednesday, 28 June 2023 at 15:35:32 UTC+2 Krack Matthias wrote:
>
> Hi Léon
>
>  
>
> Did you check the set of atomic coordinates read from the cif file for 
> close contacts possibly caused by the periodic boundary conditions?
>
>  
>
> Best
>
>  
>
> Matthias
>
>  
>
> *From: *cp... at googlegroups.com <cp... at googlegroups.com> on behalf of Léon 
> Luntadila Lufungula <Leon.luntad... at uantwerpen.be>
> *Date: *Wednesday, 28 June 2023 at 14:16
> *To: *cp2k <cp... at googlegroups.com>
> *Subject: *[CP2K:19014] Re: TiO2 slab not converging
>
> I forgot to add the cif file which is read with the input, so here it is 
> if someone needs it.
>
> On Wednesday, 28 June 2023 at 13:54:37 UTC+2 Léon Luntadila Lufungula 
> wrote:
>
> Update:
>
> I tried to optimize a 3-layer slab with altered SCF cycle settings (inner 
> loop: 15 steps, outer loop: 45 steps) and still it does not converge. The 
> convergence goes towards 2E-7 after 22 outer SCF cycles, but then doesn't 
> seem to get lower (see attachment a101-3-layer-jobID_188.out). I tried to 
> restart the calculation with altered EPS_SCF (= 1E-6) and then the 
> restarted SCF cycle converges as the convergence was already below 1E-6. 
> Unfortunately, after that the SCF again seems to only very slowly converge, 
> after 27 outer SCF steps it's still only at 8E-5 convergence (see 
> attachment a101-3-layer-jobID_189.out). Can anybody please help me out? I 
> feel like the calculation is not converging properly, as after nearly 2 
> hours it still hasn't converged one SCF cycle but I don't know what might 
> be wrong orhow to fix it... Requiring 300+ steps to reach SCF convergence 
> seems quite high to me and makes me start to think there is something 
> fundamentally wrong with my input. If anyone could look at my inputs and 
> tell me what's wrong with them, I would be forever thankful!
>
> Kind regards,
>
> Léon 
>
> P.S. Could the TZVP basis set pose a problem? I often see people use 
> DZVP-SR for similar calculations, but my promotor and co-promotor both told 
> me that TZVP is required for proper energetics and should be used in 
> production runs.
>
> On Wednesday, 28 June 2023 at 10:04:07 UTC+2 Léon Luntadila Lufungula 
> wrote:
>
> Dear all,
>
>  
>
> I am trying to determine the ideal slab thickness for an anatase (101) 
> slab but my SCF cycles are not converging. I optimized the cutoffs for the 
> anatase bulk and did a CELL_OPT calculation on the unit cell to get the 
> converged structure. From this optimized unit cell, I then used ASE to 
> build the (101) slabs  with a 20 Å vacuum width and thicknesses varying 
> from 2 to 12 layers. During the GEO_OPT calculation I keep the bottom layer 
> frozen to act as the bulk. I started the 2-layer calculation yesterday but 
> when I looked at the output today, I see that the SCF cycle fails at every 
> step of the geometry optimization (see output in attachment). Is there 
> something wrong with my setup (too tight convergence criteria, wrong SCF 
> setup, ...), or is it because a 2-layer structure is perhaps too small? The 
> changes in energy go to 1E-5 - 1E-6 but never reach the convergence 
> criteria of 1E-7 even after 300 steps (inner cycle: 10 steps, outer cycle 
> 30 steps). I would guess that it could converge if I would increase the 
> maximum number of steps, but 300 steps already seems quite a lot to me, 
> although I could be wrong...
>
>  
>
> If anyone could share their thoughts on the situation so I can continue my 
> work, I would greatly appreciate the help! Thanks in advance!
>
>  
>
> Best regards,
>
> Léon
>
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