[CP2K-user] [CP2K:17627] Re: Large discrepancy in xTB results from CP2K vs DFTB+
Magnus Rahm
magnus at compulartech.com
Wed Sep 7 14:42:30 UTC 2022
If you downloaded or cloned the repo at d56aa67 the bug fix is included.
Safest approach to compare the versions is probably not a cell optimization
but a single-point calculation (RUN_TYPE ENERGY_FORCE). The EV-curves in my
post indicate that cell relaxation with the new version would (probably
erroneously) have led to a very small cell as well, even though the
underlying energies have changed significantly.
Kind regards,
Magnus Rahm
On Wednesday, September 7, 2022 at 3:11:08 PM UTC+2 jazz... at gmail.com wrote:
> >> 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 <mag... 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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