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<p>Dear Giuseppe,</p>
<p><br>
</p>
<p><font size="2"><span style="font-size:10pt">> Out of further curiosity, a few years ago there has been a fuss over
<br>
> the "global U" approach of the pseudo-hybrid ACBN0 functional, which <br>
> had been tested on ZnO among other cases (Phys. Rev. X 2015, 5, 011006).<br>
> It seems that the ACBN0 implementation "didn't hit the market"... Is <br>
> it an active project?</span></font><br>
</p>
<p><br>
</p>
<p>As far as I know, it is still active and used in different groups. To the best of my knowledge,
<font size="2"><span style="font-size:10pt">ACBN0</span></font> is not implemented in Quantum ESPRESSO (at least in the public version). But it is implemented in other codes e.g. Octopus.</p>
<p><br>
</p>
<p>Greetings,</p>
<p>Iurii<br>
</p>
<p><br>
</p>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">--<br>
Dr. Iurii Timrov<br>
Postdoctoral Researcher<br>
<font color="808080"><font face="'Times New Roman', Times, serif"></font></font></font></div>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">STI - IMX <font color="808080">
<font face="'Times New Roman', Times, serif">- THEOS</font></font></font><font size="3" face="'Times New Roman', Times, serif" color="808080"> and NCCR - MARVEL<br>
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<font size="3" face="'Times New Roman', Times, serif" color="808080"><font size="3" face="'Times New Roman', Times, serif" color="808080">Swiss Federal Institute of Technology Lausanne (EPFL<font color="808080"><font face="'Times New Roman', Times, serif">)</font></font></font><br>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">CH-1015 Lausanne, Switzerland<br>
+41 21 69 34 881</font></div>
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<a href="http://people.epfl.ch/265334" tabindex="0" id="LPNoLP">http://people.epfl.ch/265334</a><br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> users <users-bounces@lists.quantum-espresso.org> on behalf of Giuseppe Mattioli <giuseppe.mattioli@ism.cnr.it><br>
<b>Sent:</b> Thursday, June 18, 2020 12:24:22 PM<br>
<b>To:</b> Quantum ESPRESSO users Forum<br>
<b>Subject:</b> Re: [QE-users] Problems with hp.x</font>
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<div class="PlainText"><br>
Out of further curiosity, a few years ago there has been a fuss over <br>
the "global U" approach of the pseudo-hybrid ACBN0 functional, which <br>
had been tested on ZnO among other cases (Phys. Rev. X 2015, 5, 011006).<br>
It seems that the ACBN0 implementation "didn't hit the market"... Is <br>
it an active project?<br>
Best<br>
Giuseppe<br>
<br>
Quoting Timrov Iurii <iurii.timrov@epfl.ch>:<br>
<br>
>> ...because the 2 shell is fully occupied<br>
><br>
><br>
> because the d shell is fully occupied.<br>
><br>
><br>
> Sorry!<br>
><br>
><br>
> Iurii<br>
><br>
><br>
> ________________________________<br>
> From: users <users-bounces@lists.quantum-espresso.org> on behalf of <br>
> Timrov Iurii <iurii.timrov@epfl.ch><br>
> Sent: Thursday, June 18, 2020 10:08:19 AM<br>
> To: Quantum ESPRESSO users Forum<br>
> Subject: Re: [QE-users] Problems with hp.x<br>
><br>
><br>
>> Since it's Cu(I) isn't<br>
>> that a closed shell, a d10 system aswell? I was wondering why the<br>
>> linear-response theory works in this case but not for Zn2+.<br>
><br>
><br>
> Indeed, Cu2O has the same problem as ZnO, because the 2 shell is <br>
> fully occupied. In our paper, for Cu2O we obtained U for Cu-3d <br>
> states of 11.3 eV - this is from a one-shot calculation. This value <br>
> of U is already large. If U is computed in a self-consistent way, <br>
> then at 2nd, 3rd, and next iterations U for Cu-3d states will be <br>
> larger and larger. This is because the d shell is full and it is <br>
> pushed deeper and deeper in energy with increasing U, and the <br>
> linear-response theory gives larger and larger values of U at the <br>
> subsequent iterations. I realized quite late that Cu2O is not really <br>
> a good "demonstrator" for our PRB 2018 paper - however, on the other <br>
> hand, still it is OK just for the sake of benchmarking DFPT versus <br>
> the finite-difference supercell approach of PRB 71, 035105 (2005).<br>
><br>
><br>
> Concerning the question why in the one-shot calculation Cu-3d (in <br>
> Cu2O) has U of ~11 eV and Zn-3d (in ZnO) has U of ~20 eV, is because <br>
> Zn-3d states are deeper in energy than Cu-3d states (at the DFT <br>
> level - which is typically the starting point for the HP calculation).<br>
><br>
><br>
> HTH<br>
><br>
><br>
> Iurii<br>
><br>
><br>
> --<br>
> Dr. Iurii Timrov<br>
> Postdoctoral Researcher<br>
> STI - IMX - THEOS and NCCR - MARVEL<br>
> Swiss Federal Institute of Technology Lausanne (EPFL)<br>
> CH-1015 Lausanne, Switzerland<br>
> +41 21 69 34 881<br>
> <a href="http://people.epfl.ch/265334">http://people.epfl.ch/265334</a><br>
> ________________________________<br>
> From: users <users-bounces@lists.quantum-espresso.org> on behalf of <br>
> dv009200@fh-muenster.de <dv009200@fh-muenster.de><br>
> Sent: Wednesday, June 17, 2020 11:42:28 PM<br>
> To: Quantum ESPRESSO users Forum<br>
> Subject: Re: [QE-users] Problems with hp.x<br>
><br>
> Thanks again thats for sure very helpful.<br>
><br>
> Just out of curiosity I may have one more question: In the paper thats the<br>
> basis of the hp.x code (I. Timrov, N. Marzari, M. Cococcioni, Phys. Rev. B<br>
> 98, 085127, DOI:10.1103/PhysRevB.98.085127) the Hubbard U parameter of<br>
> Cu2O is computed by the linear-response theory. Since it's Cu(I) isn't<br>
> that a closed shell, a d10 system aswell? I was wondering why the<br>
> linear-response theory works in this case but not for Zn2+.<br>
><br>
> Best regards<br>
><br>
> Dominik Voigt<br>
><br>
> Dominik Voigt<br>
> PhD Student University of Applied Sciences Münster<br>
> Department of Physical Chemistry<br>
><br>
><br>
><br>
>><br>
>> Dear Dominik<br>
>><br>
>>> the method you suggested Giuseppe. I don't quite know whats the 'right'<br>
>>> distance between the valence band and the d-band? Can I use experimental<br>
>>> data from xps/ups spectra for that matter or do you have other<br>
>>> suggestions?<br>
>><br>
>> Yes, it is actually what I did with ZnO. As I remarked in my previous<br>
>> message, it is going to work well if you apply the correction also to<br>
>> the S 3p shell, in a DFT+U(Zn,S) fashion. In wurtzite ZnO the strong<br>
>> curvature of the Zn 4s conduction band is such that the CB is<br>
>> substantially free from delocalization error and it is a good absolute<br>
>> reference. If you know the position of the Fermi level (which can<br>
>> depend on intrinsic defects in real samples) with respect to the CB,<br>
>> then you can reasonably estimate the position of the Zn 3d band.<br>
>> I hope I've not added entropy...<br>
>> Best<br>
>> Giuseppe<br>
>><br>
>> Quoting dv009200@fh-muenster.de:<br>
>><br>
>>> Thanks all for the helpful comments and interesting papers. I'm fine<br>
>>> correcting the delocalization error of the Zn 3d states 'semiempirical'<br>
>>> by<br>
>>> the method you suggested Giuseppe. I don't quite know whats the 'right'<br>
>>> distance between the valence band and the d-band? Can I use experimental<br>
>>> data from xps/ups spectra for that matter or do you have other<br>
>>> suggestions?<br>
>>><br>
>>> Best regards<br>
>>><br>
>>> Dominik Voigt<br>
>>><br>
>>> Dominik Voigt<br>
>>> PhD Student University of Applied Sciences Münster<br>
>>> Department of Physical Chemistry<br>
>>><br>
>>><br>
>>><br>
>>>> Dear All,<br>
>>>><br>
>>>><br>
>>>> Giuseppe is right, this is a limitation of the current implementation<br>
>>>> of<br>
>>>> the linear-response theory to compute Hubbard parameters for<br>
>>>> closed-shell<br>
>>>> systems (like ZnO, ZnS, etc.). This "limitation" is known, and there is<br>
>>>> some comment about this in q-e/HP/Doc/README. Please check this paper<br>
>>>> for<br>
>>>> more details:<br>
>>>> <<a href="https://aip.scitation.org/doi/10.1063/1.4869718">https://aip.scitation.org/doi/10.1063/1.4869718</a>><br>
>>>><br>
>>>> <a href="https://aip.scitation.org/doi/10.1063/1.4869718">https://aip.scitation.org/doi/10.1063/1.4869718</a><br>
>>>><br>
>>>><br>
>>>> The developers of the HP code are planning to investigate this issue in<br>
>>>> more detail, and hopefully we will come out with some solution in the<br>
>>>> near<br>
>>>> future.<br>
>>>><br>
>>>><br>
>>>> Best regards,<br>
>>>><br>
>>>> Iurii<br>
>>>><br>
>>>><br>
>>>> --<br>
>>>> Dr. Iurii Timrov<br>
>>>> Postdoctoral Researcher<br>
>>>> STI - IMX - THEOS and NCCR - MARVEL<br>
>>>> Swiss Federal Institute of Technology Lausanne (EPFL)<br>
>>>> CH-1015 Lausanne, Switzerland<br>
>>>> +41 21 69 34 881<br>
>>>> <a href="http://people.epfl.ch/265334">http://people.epfl.ch/265334</a><br>
>>>> ________________________________<br>
>>>> From: users <users-bounces@lists.quantum-espresso.org> on behalf of<br>
>>>> Giuseppe Mattioli <giuseppe.mattioli@ism.cnr.it><br>
>>>> Sent: Monday, June 15, 2020 10:55:59 PM<br>
>>>> To: Quantum ESPRESSO users Forum<br>
>>>> Subject: Re: [QE-users] Problems with hp.x<br>
>>>><br>
>>>><br>
>>>> Dear Dominik<br>
>>>> I suppose that the problem is not in hp.x, but in the application of<br>
>>>> the linear-response method itself to Zn(2+). Zn(2+) is a d10<br>
>>>> transition metal, with the 3d band fully occupied. In ZnO, e.g., the<br>
>>>> Zn 3d band is quite narrow and placed below the O 2p valence band, and<br>
>>>> I suppose that the same holds for ZnS, with the Zn 3d band pushing up<br>
>>>> the S 3p band. When you apply the LR method to Zn, you compute<br>
>>>> quantities such as d(alpha)/dn, where alpha is the (small)<br>
>>>> perturbation and n is the occupation number of d orbitals on site I<br>
>>>> (see International Journal of Quantum Chemistry 2014, 114, 14 for<br>
>>>> details). If the shell is full, then you can perturb whatever you want<br>
>>>> but you will never obtain more than the full occupation of the shell<br>
>>>> that you already have in the unperturbed system. This is likely the<br>
>>>> reason for the crazy values of LR U you obtain. If you want to correct<br>
>>>> the strong delocalization error of the Zn 3d narrow band within the<br>
>>>> DFT+U formalism, then you must use a "semiempirical" approach,<br>
>>>> choosing, e.g., the U value that places the Zn 3d shell at the correct<br>
>>>> distance from the valence band maximum. In this case, I would<br>
>>>> recommend the use of a second +U correction on the S 3p shell, which<br>
>>>> should ensure a good recovery of the ZnS band gap. I've satisfactorily<br>
>>>> used this scheme in the case of ZnO in several publications, from<br>
>>>> which you may want to take inspiration (Adv. Energy Mater. 2014, 4,<br>
>>>> 1301694).<br>
>>>> HTH<br>
>>>> Giuseppe<br>
>>>><br>
>>>> Quoting dv009200@fh-muenster.de:<br>
>>>><br>
>>>>> Hello everyone,<br>
>>>>><br>
>>>>> I'm trying to calculate the hubbard u parameter for Zn in Zinc sulfide<br>
>>>>> (sphalerite structure) with the help of the hp.x code. The<br>
>>>>> calculations<br>
>>>>> terminate normally without any errors. The problem is that I get<br>
>>>>> (presumably) way too high values for U that also won't converge (if I<br>
>>>>> take<br>
>>>>> the value I got from a one-shot calculation and plug it in the SCF<br>
>>>>> input<br>
>>>>> and then redo the HP calculation).<br>
>>>>><br>
>>>>> For example in the first step I calculate a U = 75.7035 in the second<br>
>>>>> iteration I get U = 804.2405 and in the third U = 30999.2684.<br>
>>>>><br>
>>>>> This seems unreasonable considering that the calculations for the<br>
>>>>> provided<br>
>>>>> examples in the 'HP' folder work fine and converge fast without such a<br>
>>>>> massive change to a certain value for U using the above described<br>
>>>>> scheme.<br>
>>>>><br>
>>>>> Has someone an idea what is causing this trouble in my system? I<br>
>>>>> already<br>
>>>>> tried different PPs, functionals, U_projection_type, thresholds and k<br>
>>>>> and<br>
>>>>> q point grids all without success.<br>
>>>>><br>
>>>>> Below is my input for the scf and hp calculation<br>
>>>>><br>
>>>>> SCF-input:<br>
>>>>>  &control<br>
>>>>> calculation='scf'<br>
>>>>> restart_mode='from_scratch',<br>
>>>>> pseudo_dir = '/home/dominik/codes/QE6.5/pseudo/'<br>
>>>>> outdir='/home/dominik/codes/QE6.5/tempdir/'<br>
>>>>> prefix='zns'<br>
>>>>> /<br>
>>>>> &SYSTEM<br>
>>>>> ibrav = 2<br>
>>>>> celldm(1)=10.291937439<br>
>>>>> nat = 2<br>
>>>>> ntyp = 2<br>
>>>>> ecutwfc = 60.0<br>
>>>>> ecutrho= 720.0<br>
>>>>> lda_plus_u = .true.<br>
>>>>> lda_plus_u_kind = 0<br>
>>>>> U_projection_type = 'atomic'<br>
>>>>> Hubbard_U(1) = 1d-8<br>
>>>>> /<br>
>>>>> &electrons<br>
>>>>> mixing_beta=0.7<br>
>>>>> conv_thr=1d-15<br>
>>>>> /<br>
>>>>> ATOMIC_SPECIES<br>
>>>>> Zn 65.39 Zn.pbe-dn-rrkjus_psl.0.2.2.UPF<br>
>>>>> S 32.07 S.pbe-n-rrkjus_psl.0.1.UPF<br>
>>>>> ATOMIC_POSITIONS {alat}<br>
>>>>> Zn 0.000000 0.000000 0.000000<br>
>>>>> S 0.250000 0.250000 0.250000<br>
>>>>> K_POINTS automatic<br>
>>>>> 12 12 12 0 0 0<br>
>>>>><br>
>>>>><br>
>>>>> HP-input:<br>
>>>>> &inputhp<br>
>>>>> prefix='zns'<br>
>>>>> outdir='/home/dominik/codes/QE6.5/tempdir/'<br>
>>>>> nq1 = 2<br>
>>>>> nq2 = 2<br>
>>>>> nq3 = 2<br>
>>>>> conv_thr_chi = 1.0d-10<br>
>>>>> iverbosity =2<br>
>>>>> /<br>
>>>>><br>
>>>>><br>
>>>>> Best regards<br>
>>>>><br>
>>>>><br>
>>>>> Dominik Voigt<br>
>>>>><br>
>>>>> Dominik Voigt<br>
>>>>> PhD Student University of Applied Sciences Münster<br>
>>>>> Department of Physical Chemistry<br>
>>>>><br>
>>>>> _______________________________________________<br>
>>>>> Quantum ESPRESSO is supported by MaX<br>
>>>>> (<a href="http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso</a>>>)<br>
>>>>> users mailing list users@lists.quantum-espresso.org<br>
>>>>> <a href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
>>>><br>
>>>><br>
>>>><br>
>>>> GIUSEPPE MATTIOLI<br>
>>>> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA<br>
>>>> Via Salaria Km 29,300 - C.P. 10<br>
>>>> I-00015 - Monterotondo Scalo (RM)<br>
>>>> Mob (*preferred*) +39 373 7305625<br>
>>>> Tel + 39 06 90672342 - Fax +39 06 90672316<br>
>>>> E-mail: <giuseppe.mattioli@ism.cnr.it><br>
>>>><br>
>>>> _______________________________________________<br>
>>>> Quantum ESPRESSO is supported by MaX<br>
>>>> (<a href="http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso</a>>>)<br>
>>>> users mailing list users@lists.quantum-espresso.org<br>
>>>> <a href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
>>>> _______________________________________________<br>
>>>> Quantum ESPRESSO is supported by MaX<br>
>>>> (<a href="http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso</a>>)<br>
>>>> users mailing list users@lists.quantum-espresso.org<br>
>>>> <a href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
>>><br>
>>><br>
>>> _______________________________________________<br>
>>> Quantum ESPRESSO is supported by MaX<br>
>>> (<a href="http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso</a>>)<br>
>>> users mailing list users@lists.quantum-espresso.org<br>
>>> <a href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
>><br>
>><br>
>><br>
>> GIUSEPPE MATTIOLI<br>
>> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA<br>
>> Via Salaria Km 29,300 - C.P. 10<br>
>> I-00015 - Monterotondo Scalo (RM)<br>
>> Mob (*preferred*) +39 373 7305625<br>
>> Tel + 39 06 90672342 - Fax +39 06 90672316<br>
>> E-mail: <giuseppe.mattioli@ism.cnr.it><br>
>><br>
>> _______________________________________________<br>
>> Quantum ESPRESSO is supported by MaX <br>
>> (<a href="http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso</a>>)<br>
>> users mailing list users@lists.quantum-espresso.org<br>
>> <a href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
><br>
><br>
> _______________________________________________<br>
> Quantum ESPRESSO is supported by MaX <br>
> (<a href="http://www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso</a>>)<br>
> users mailing list users@lists.quantum-espresso.org<br>
> <a href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
<br>
<br>
<br>
GIUSEPPE MATTIOLI<br>
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA<br>
Via Salaria Km 29,300 - C.P. 10<br>
I-00015 - Monterotondo Scalo (RM)<br>
Mob (*preferred*) +39 373 7305625<br>
Tel + 39 06 90672342 - Fax +39 06 90672316<br>
E-mail: <giuseppe.mattioli@ism.cnr.it><br>
<br>
_______________________________________________<br>
Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso</a>)<br>
users mailing list users@lists.quantum-espresso.org<br>
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