<div>Hi,</div><div> </div><div>Thanks for the prompt fix! It made a significant difference but doesn't seem to resolve the discrepancy with DFTB+ (please see attached figure). Mulliken charges changed "in the right direction" but still differ very significantly compared to DFTB+.</div><div> </div><div>Kind regards,</div><div>Magnus Rahm</div><div> </div><div> </div> <div class="gmail_quote"><div dir="auto" class="gmail_attr">On Tuesday, September 6, 2022 at 5:36:30 PM UTC+2 jgh wrote: </div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Hi the updates are now on Github (Trunk version). This should at least fix the strange behavior for changes of EPS_DEFAULT. regards JH ________________________________________ From: <a href data-email-masked rel="nofollow">cp...@googlegroups.com</a> <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>> on behalf of Jürg Hutter <<a href data-email-masked rel="nofollow">hut...@chem.uzh.ch</a>> Sent: Tuesday, September 6, 2022 11:37 AM To: <a href data-email-masked rel="nofollow">cp...@googlegroups.com</a> Subject: Re: [CP2K:17614] Re: Large discrepancy in xTB results from CP2K vs DFTB+ Hi I think I found the problem. This is in fact a bug in CP2K and is related to the damping of the "short range" part of the Coulomb term. As mentioned before this short range part is not short range at all, even diverging in periodic systems. We use a damping function for this term and the radius is taken from the range of the basis function on each atom. The bug is now, that this range is not a constant but depends on EPS_DEFAULT. I will work on a solution, but at least the default settings will cause considerable changes in the energies of periodic systems. regards JH ________________________________________ From: <a href data-email-masked rel="nofollow">cp...@googlegroups.com</a> <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>> on behalf of Magnus Rahm <<a href data-email-masked rel="nofollow">mag...@compulartech.com</a>> Sent: Monday, September 5, 2022 3:19 PM To: cp2k Subject: Re: [CP2K:17609] Re: Large discrepancy in xTB results from CP2K vs DFTB+ Hi, Thank you for valuable input! Here's a breakdown of energies for a periodic LiO2 system (where CP2K and DFTB+ disagree). CP2K: Core Hamiltonian energy: -609.45757320827579 Repulsive potential energy: 2.86335541921533 Electronic energy: -65.73940900376786 DFTB3 3rd order energy: 9.00274299587460 Dispersion energy: -2.00065978643714 Correction for halogen bonding: 0.00000000000000 Total energy: -665.33154358339084 outer SCF iter = 1 RMS gradient = 0.49E-06 energy = -665.<a href="tel:(331)%20543-5834" value="+13315435834" target="_blank" rel="nofollow">3315435834</a> outer SCF loop converged in 1 iterations or 10 steps And the same system with DFTB+ (I don't know this is the best breakdown I can get from DFTB+? This info is from detailed.out.): Fermi level: -0.1574062769 H -4.2832 eV Band energy: -254.9890864567 H -6938.6061 eV TS: 0.0000000000 H 0.0000 eV Band free energy (E-TS): -254.9890864567 H -6938.6061 eV Extrapolated E(0K): -254.9890864567 H -6938.6061 eV Input / Output electrons (q): 864.0000000000 864.0000000000 Energy H0: -610.3586854777 H -16608.7049 eV Energy SCC: 13.1915555608 H 358.9605 eV Total Electronic energy: -597.1671299169 H -16249.7444 eV Repulsive energy: 0.0000000000 H 0.0000 eV Total energy: -597.1671299169 H -16249.7444 eV Extrapolated to 0: -597.1671299169 H -16249.7444 eV Total Mermin free energy: -597.1671299169 H -16249.7444 eV Force related energy: -597.1671299169 H -16249.7444 eV ---------------------------------------------------------------------------------------------------------------- For reference, here are the equivalent breakdowns for the LiF molecule, where the total energies do match quite well. CP2K: Core Hamiltonian energy: -5.57594122418510 Repulsive potential energy: 0.00036401843654 Electronic energy: 0.08477836575096 DFTB3 3rd order energy: -0.00385103760005 Dispersion energy: -0.00008325087778 Correction for halogen bonding: 0.00000000000000 Total energy: -5.49473312847544 outer SCF iter = 1 RMS gradient = 0.12E-06 energy = -5.4947331285 outer SCF loop converged in 1 iterations or 25 steps DFTB+ Fermi level: -0.<a href="tel:(343)%20487-4008" value="+13434874008" target="_blank" rel="nofollow">3434874008</a> H -9.3468 eV Band energy: -3.7493389034 H -102.0247 eV TS: 0.0000000000 H 0.0000 eV Band free energy (E-TS): -3.7493389034 H -102.0247 eV Extrapolated E(0K): -3.7493389034 H -102.0247 eV Input / Output electrons (q): 8.0000000444 8.0000000000 Energy H0: -5.<a href="tel:(574)%20345-1431" value="+15743451431" target="_blank" rel="nofollow">5743451431</a> H -151.6856 eV Energy SCC: 0.0807122067 H 2.1963 eV Total Electronic energy: -5.4936329365 H -149.4894 eV Repulsive energy: 0.0000000000 H 0.0000 eV Total energy: -5.4936329365 H -149.4894 eV Extrapolated to 0: -5.4936329365 H -149.4894 eV Total Mermin free energy: -5.4936329365 H -149.4894 eV Force related energy: -5.4936329365 H -149.4894 eV ---------------------------------------------------------------------------------------------------------------- > I recently run variable-cell optimization of various molecular crystals and I found xTB@CP2K ultra sensitive to EPS_DEFAULT. Tested from 1e-5 to 1e-24 (with EPS_SCF 1e-8), and no convergence happened. Thank you for sharing this info! I tried a series of calculations with LiO2 using varying values of EPS_DEFAULT (using default EPS_SCF) and found the same effect; no convergence with EPS_DEFAULT (or perhaps unreasonably slow convergence). I attach a figure showing these results, including the energy broken down into the different parts as specified in the CP2K output. Note the energy scale, the changes with EPS_DEFAULT are really quite substantial. In the LiF (non-PBC) case, the corresponding curves look completely flat on the same scale. I don't know what to make of this result, but perhaps someone else does? Magnus [X] On Monday, September 5, 2022 at 12:18:26 PM UTC+2 <a href data-email-masked rel="nofollow">jazz...@gmail.com</a> wrote: I recently run variable-cell optimization of various molecular crystals and I found xTB@CP2K ultra sensitive to EPS_DEFAULT. Tested from 1e-5 to 1e-24 (with EPS_SCF 1e-8), and no convergence happened. I just ended up with EPS_DEFAULT 1e-10 as a "gut" choice. Also, the behavior of xTB@CP2K is doutfull with MD even at ambiant conditions, where the converged volume is barely larget than at 0K. Depending on EPS_DEFAULT, it can even be smaller at ambient T. Weird. The behavior of DFTB2@CP2K is far better. I found that DFTB+ has other issues. xTB@DFTB+ has no convergence issue, but the recommended variable-cell optimization algorithm has flaws. The unit cell and a supercell does NOT always end up with related lattice parameters. The main issue is that some 90° angles are not preserved with DFTB+ whereas CP2K does (with no symmetry enforced, obviously). Some inconsistencies appears in DFTB+ with a lattice dimensions < 10 angstroms in the unit cell versus > 10 angstroms in the supercell. A proper tight mesh of k-points does not improve. So I'm afraid that xTB@DFTB+ (or DFTB+, actually) cannot be a relevant choice for crystal structure predictions, for instance. xTB may be unreliable with CP2K and DFTB+, but for the different reasons above. You can check these weird behaviors with your own crystals of interest. Xavier Le lun. 5 sept. 2022, 3:59 AM, Jürg Hutter <<a href data-email-masked rel="nofollow">hut...@chem.uzh.ch</a>> a écrit : Hi thank you for testing. Could you send a break down of the energies for the LiF molecule for the two codes? That might help to recognize the source of the difference. regards JH ________________________________________ From: <a href data-email-masked rel="nofollow">cp...@googlegroups.com</a> <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>> on behalf of Magnus Rahm <<a href data-email-masked rel="nofollow">mag...@compulartech.com</a>> Sent: Monday, September 5, 2022 8:40 AM To: cp2k Subject: [CP2K:17599] Re: Large discrepancy in xTB results from CP2K vs DFTB+ For the record, the problem is the same in CP2K version 2022.1. On Thursday, September 1, 2022 at 12:48:35 PM UTC+2 Magnus Rahm wrote: Dear all, I want to use CP2K (version 8.2, trying to get a more recent version compiled) together with xTB for a crystal containing Li and O. I get strange results already for a simple LiO2 crystal: * There is a very large discrepancy compared to DFTB+ (version 22.1). * Mulliken charges tend to be large, meaning that CHECK_ATOMIC_CHARGES stops the SCF. If I turn it off, the system tends to converge systematically to values just outside the "chemical range". Mulliken charges obtained by DFTB+ are significantly smaller (and within "chemical range"). * The energy-volume curve looks strange and very different from DFTB+. I have tried converging with respect to system size and the EWALD / ALPHA and GMAX parameters, but they have only a marginal impact. I have tried similar calculations for a number of periodic systems. Sometimes I get agreement, sometimes not. I also tried calculations for CO and NO molecules which agree perfectly between CP2K and DFTB+, whereas an artificial LiF molecule does not. A perhaps related issue was reported in <a href="https://groups.google.com/g/cp2k/c/oFwgGcQuySs" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=en&q=https://groups.google.com/g/cp2k/c/oFwgGcQuySs&source=gmail&ust=1662582216595000&usg=AOvVaw1W_zlk8fr-SFs5_I0NDvm0">https://groups.google.com/g/cp2k/c/oFwgGcQuySs</a> but the solutions suggested there did not solve my problem. I attach input scripts for CP2K and DFTB+, as well as a figure showing the E-V curve for LiO2 obtained with CP2K and DFTB+. I'm new to CP2K, DFTB+ and xTB so I suspect I have made some simple mistake, and any advice is appreciated. Kind regards, Magnus Rahm -- You received this message because you are subscribed to the Google Groups "cp2k" group. To unsubscribe from this group and stop receiving emails from it, send an email to <a href data-email-masked rel="nofollow">cp2k+uns...@googlegroups.com</a><mailto:<a href data-email-masked rel="nofollow">cp2k+uns...@googlegroups.com</a>>. 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