<br />Dear Lobna,<div><br /></div><div>Thanks for the reply! </div><div><br /></div><div>I can see that the total energies may differ from those obtained with other QC software packages as the computational methods (implementation, basis set, etc.) might be different, but I would think that this does not influence the convergence of the total energy as a function of the cutoff. </div><div><br /></div><div>I could indeed compare the lattice parameters of a calculated anatase unit cell at different cutoffs with those found experimentally, but wouldn't it be computationally expensive to check as I would have to do CELL_OPT calculations for each cutoff as opposed to simple ENERGY calculations? Also, should thermal effects be taken into account in some way as CELL_OPT calculations are at 0K and the experimental CIF was recorded at RT?</div><div><br /></div><div>You also mention that Ti requires an optimization of the basis set and pseudopotentials, but I don't know how I would go about doing this optimization, do you have any suggestions?</div><div><br /></div><div>Kind regards,</div><div>Léon</div><div><br /></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Monday, 5 June 2023 at 09:19:01 UTC+2 Lobna Saeed wrote:<br/></div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div dir="ltr"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I had the same exact issues with the convergence !! exactly the same. I was also confused about the largest exponent as well. When I used this <a href="https://www.cp2k.org/faq:cutoff" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://www.cp2k.org/faq:cutoff&source=gmail&ust=1686042360861000&usg=AOvVaw3TDs960C04wDFLO-GlyNWv">https://www.cp2k.org/faq:cutoff</a>, I got a very high cutoff value which when I employed deviated very much from the experimental values. So may be you need to look at other values, other than the total energies. The total energies we get here are not by any mean realistic. When I compared the total energy values I got from VASP with the values we get from CP2K (for single elements), I got completely different results. So when I increased the basis sets I was able to get the same values for Al and Nb, other elements like Ti REALLY need optimization of the basis sets and pseudopotentials. Therefore you should try to look at other values other than the total energies (like the lattice parameters for example) to be able to deduce a final conclusion about the cutoff value.</blockquote></div><br><div class="gmail_quote"></div><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jun 5, 2023 at 6:59 AM Léon Luntadila Lufungula <<a href data-email-masked rel="nofollow">Leon.luntad...@uantwerpen.be</a>> wrote:<br></div></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Dear all,<div><br></div><div>Apparently I forgot to add my input file in my previous message, so I have included it as an attachment in this reply. I'm eagerly looking forward to your replies and thank you in advance.</div><div><br></div><div>Kind regards,</div><div>Léon<br><br></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Friday, 2 June 2023 at 15:44:38 UTC+2 Léon Luntadila Lufungula wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US">Dear all,</p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US"> </p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US">I am
currently switching from Quantum ESPRESSO (QE) to CP2K as my main computational
software package (currently using version 8.2) and I am struggling a bit with
the convergence tests for the PW cutoffs (REL_CUTOFF and CUTOFF). My intended
structures to investigate are moderate-sized organic molecules adsorbed onto a
(101) surface of anatase (TiO2) and as such I am using an optimized structure
from my QE calculations as a representative system to do my convergence tests
on (see attached file 3mppa-md1.inp). I based my method on the method proposed
by Prof. Hütter in a previous <a href="https://groups.google.com/g/cp2k/c/ySUAYEgwmhc" rel="nofollow" target="_blank" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://groups.google.com/g/cp2k/c/ySUAYEgwmhc&source=gmail&ust=1686042360861000&usg=AOvVaw3ZGHPr47bWSVOzumgZt5-r">post</a>, whereby I first
set REL_CUTOFF=CUTOFF and increase the value until I reach convergence. The
results I got are the following:</p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US"> </p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"># Grid cutoff vs total energy</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"># Date: Fri Jun 2 14:09:32
CEST 2023</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"># PWD: /home/lluntadilal/cp2k/scf/dft/test/final/convergence/cutoff</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"># Cutoff (Ry) | Relative cutoff (Ry) | Total energy (a.u.) | Total
charge (a.u.)</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 300 300 -3303.<a href="tel:(469)%20391-9783" value="+14693919783" rel="nofollow" target="_blank">4693919783</a> 0.0000049144</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 400 400 -3303.4678396250 -0.0000000118</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 500 500 -3303.4658109937 -0.0000000003</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 600 600 -3303.4675587607 -0.0000000003</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 700 700 -3303.4671967038 -0.0000000003</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 800 800 -3303.4663947747 -0.0000000003</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 900 900 -3303.4659684557 -0.0000000003</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1000 1000 -3303.4657584430 -0.0000000002</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1100 1100 -3303.4651289391 -0.0000000002</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1200 1200 -3303.4650897922 -0.0000000003</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1300 1300 -3303.4651986119 -0.0000000002</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1400 1400 -3303.4651800964 -0.0000000002</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1500 1500 -3303.4650037920 -0.0000000002</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1600 1600 -3303.4650956961 -0.0000000002</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1700 1700 -3303.4651701336 -0.0000000002</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1800 1800 -3303.4651578599 -0.0000000002</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 1900 1900 -3303.4651999129 -0.0000000002</p>
<p style="margin:0in 0in 0in 0.375in;font-family:Calibri;font-size:11pt" lang="en-US"> 2000 2000 -3303.4651936486 -0.0000000002</p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US"> </p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US">I have
several questions about this:</p>
<ol type="1" style="direction:ltr;unicode-bidi:embed;margin-top:0in;margin-bottom:0in;font-family:Calibri;font-size:11pt">
<li value="1" style="margin-top:0px;margin-bottom:0px;vertical-align:middle" lang="en-US"><span style="font-size:11pt">I would
like to be able to give the energies of my structures accurate up to 0.01
kJ/mol which is about 1.10^-6 a.u. Unfortunately, I only reach this level
of accuracy at a cutoff of 2000 Ry… This seems quite a large cutoff as I
see similar calculations with cutoffs between 400-1200 Ry and also because
the charge is already converged at 500 Ry. Am I doing something wrong or
is my criteria just too strict? Does this perhaps have anything to do with
the fact that the relative position of the atoms to the grid points
changes with the cutoff as mentioned by Prof. Hütter in his post?</span></li>
<li style="margin-top:0px;margin-bottom:0px;vertical-align:middle" lang="en-US"><span style="font-size:11pt">The </span><a href="https://www.cp2k.org/faq:cutoff" rel="nofollow" target="_blank" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://www.cp2k.org/faq:cutoff&source=gmail&ust=1686042360861000&usg=AOvVaw3TDs960C04wDFLO-GlyNWv"><span style="font-size:11pt">faq</span></a><span style="font-size:11pt"> and </span><a href="https://www.cp2k.org/events:2018_summer_school:converging_cutoff" rel="nofollow" target="_blank" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://www.cp2k.org/events:2018_summer_school:converging_cutoff&source=gmail&ust=1686042360861000&usg=AOvVaw2S5QLH4fpWDm48vdyy-dA-"><span style="font-size:11pt">converging cutoff exercise</span></a><span style="font-size:11pt"> state that the PW cutoff
should be large enough to properly represent the Gaussian with the largest
exponent, which in my system seems to be oxygen with an exponent around
10.4 for the DZVP-MOLOPT-SR-GTH basis set. So is it then correct to use
such a complex structure (3-layer slab with adsorbate and 30Å vacuum
width) with "complex" options (dipole and dispersion
corrections) as input for my convergence tests or could I use a simpler
structure (e.g. an oxygen molecule in a box) with more basic settings (no
corrections) or would this be insufficient?</span></li>
<li style="margin-top:0px;margin-bottom:0px;vertical-align:middle" lang="en-US"><span style="font-size:11pt">I may be planning to use
larger basis sets ("regular" DZVP, TZVP or TZV2P) of the MOLOPT
family in the future and I have seen that the largest exponents for these
sets is the same as that for the smaller DZVP-SR basis set (10.4 for
oxygen). Is it correct then to assume that once I obtain optimized cutoffs
for DZVP-SR, these can be kept when switching to any of the larger basis
sets?</span></li>
<li style="margin-top:0px;margin-bottom:0px;vertical-align:middle" lang="en-US"><span style="font-size:11pt">Lastly, I would like to ask
for some general feedback on the input for my slab calculation as this is
my first calculation on CP2K and I'm still getting used to all the
settings. Is it okay to use 3D periodicity with a large vacuum space and a
dipole correction or is it better to use 2D periodicity with a
corresponding Poisson solver (e.g. MT, analytic or wavelet)? Is it okay to
use the WC functional with basis sets, pseudopotentials and D3 settings
optimized for PBE?</span></li>
</ol>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US"> </p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US">Any help
would be greatly appreciated!</p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US"> </p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US">Kind
regards,</p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US">Léon</p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US"> </p>
<p style="margin:0in;font-family:Calibri;font-size:11pt" lang="en-US">P.S. For
those looking at my structure in a graphical environment and noticing that some
atoms are outside the unit cell. This is due to the fact that my cell was
monoclinic and I made the unit cell orthorhombic to save computational time and
trouble (some codes have trouble dealing with cells that are not orthorhombic),
but I did not yet wrap all my atoms into the unit cell. However, I don't think this should be a problem under PBC.</p></blockquote></div>
<p></p></blockquote></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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