[CP2K-user] [CP2K:17623] Re: Large discrepancy in xTB results from CP2K vs DFTB+
Xavier Bidault
jazzquark at gmail.com
Wed Sep 7 13:10:53 UTC 2022
>> Could you remind me how to update CP2K 2022.1 to include this bug fix?
> I think the easiest approach is to use Docker (following these
instructions: https://github.com/cp2k/cp2k/tree/master/tools/docker),
unless you want to clone the CP2K repo from github and compile from scratch.
I tried yesterday with git clone and started from scratch. The downloaded
version (git:d56aa67) should have the xTB bug fix mentioned above (?), but
when I run variable-cell optimizations of beta-HMX with various EPS_DEFAULT
I find the exact same results as with CP2K 7.1. What's the right git
version for this bug fix? Should I copy the git folder instead of using git
clone? I mean, how to get the Trunk version you're talking about?
On Wed, Sep 7, 2022 at 7:20 AM Magnus Rahm <magnus at compulartech.com> wrote:
> Btw, I can confirm that the energy now converges with EPS_DEFAULT also for
> the LiO2 system, although the convergence is perhaps a bit slower (=very
> small EPS_DEFAULT values needed) than what one might have expected (see
> LiO2-EPS_DEFAULT.pdf). The figure I attached in my previous post was made
> with EPS_DEFAULT at the default value, if I use 1e-24 I get a bit closer to
> DFTB+ but still there is a weird slope in the E-V curve (EV-LiO2.pdf).
>
> Furthermore, I had a look at the energy broken down into its different
> contributions as a function of volume (LiO2-energies-split.pdf), and FWIW
> it indicates that the electronic energy is responsible for the unexpected
> slope in the E-V curve (perhaps that was already obvious?).
>
> > Could you remind me how to update CP2K 2022.1 to include this bug fix?
>
> I think the easiest approach is to use Docker (following these
> instructions: https://github.com/cp2k/cp2k/tree/master/tools/docker),
> unless you want to clone the CP2K repo from github and compile from scratch.
>
> Kind regards,
> Magnus Rahm
>
>
> On Wednesday, September 7, 2022 at 2:16:23 AM UTC+2 jazz... at gmail.com
> wrote:
>
>> Thank you. Could you remind me how to update CP2K 2022.1 to include this
>> bug fix?
>>
>> On Tue, Sep 6, 2022 at 10:36 AM Jürg Hutter <hut... at chem.uzh.ch> wrote:
>>
>>> 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: cp... at googlegroups.com <cp... at googlegroups.com> on behalf of Jürg
>>> Hutter <hut... at chem.uzh.ch>
>>> Sent: Tuesday, September 6, 2022 11:37 AM
>>> To: cp... at googlegroups.com
>>> 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: cp... at googlegroups.com <cp... at googlegroups.com> on behalf of
>>> Magnus Rahm <mag... at compulartech.com>
>>> 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.
>>> 3315435834 <(331)%20543-5834>
>>> 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: -0.3434874008 <(343)%20487-4008> 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: -5.5743451431 <(574)%20345-1431> 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 at 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 jazz... at gmail.com
>>> wrote:
>>> I recently run variable-cell optimization of various molecular crystals
>>> and I found xTB at 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 at 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 at CP2K is far better.
>>>
>>> I found that DFTB+ has other issues. xTB at 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 at 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 <hut... at chem.uzh.ch> 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: cp... at googlegroups.com <cp... at googlegroups.com> on behalf of
>>> Magnus Rahm <mag... at compulartech.com>
>>> 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
>>> https://groups.google.com/g/cp2k/c/oFwgGcQuySs 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
>>>
>>>
>>>
>>>
>>>
>>>
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