> ...because the 2 shell is fully occupied
because the d shell is fully occupied. Sorry! Iurii ________________________________ From: users <users-boun...@lists.quantum-espresso.org> on behalf of Timrov Iurii <iurii.tim...@epfl.ch> Sent: Thursday, June 18, 2020 10:08:19 AM To: Quantum ESPRESSO users Forum Subject: Re: [QE-users] Problems with hp.x > Since it's Cu(I) isn't > that a closed shell, a d10 system aswell? I was wondering why the > linear-response theory works in this case but not for Zn2+. Indeed, Cu2O has the same problem as ZnO, because the 2 shell is fully occupied. In our paper, for Cu2O we obtained U for Cu-3d states of 11.3 eV - this is from a one-shot calculation. This value of U is already large. If U is computed in a self-consistent way, then at 2nd, 3rd, and next iterations U for Cu-3d states will be larger and larger. This is because the d shell is full and it is pushed deeper and deeper in energy with increasing U, and the linear-response theory gives larger and larger values of U at the subsequent iterations. I realized quite late that Cu2O is not really a good "demonstrator" for our PRB 2018 paper - however, on the other hand, still it is OK just for the sake of benchmarking DFPT versus the finite-difference supercell approach of PRB 71, 035105 (2005). Concerning the question why in the one-shot calculation Cu-3d (in Cu2O) has U of ~11 eV and Zn-3d (in ZnO) has U of ~20 eV, is because Zn-3d states are deeper in energy than Cu-3d states (at the DFT level - which is typically the starting point for the HP calculation). HTH Iurii -- Dr. Iurii Timrov Postdoctoral Researcher STI - IMX - THEOS and NCCR - MARVEL Swiss Federal Institute of Technology Lausanne (EPFL) CH-1015 Lausanne, Switzerland +41 21 69 34 881 http://people.epfl.ch/265334 ________________________________ From: users <users-boun...@lists.quantum-espresso.org> on behalf of dv009...@fh-muenster.de <dv009...@fh-muenster.de> Sent: Wednesday, June 17, 2020 11:42:28 PM To: Quantum ESPRESSO users Forum Subject: Re: [QE-users] Problems with hp.x Thanks again thats for sure very helpful. Just out of curiosity I may have one more question: In the paper thats the basis of the hp.x code (I. Timrov, N. Marzari, M. Cococcioni, Phys. Rev. B 98, 085127, DOI:10.1103/PhysRevB.98.085127) the Hubbard U parameter of Cu2O is computed by the linear-response theory. Since it's Cu(I) isn't that a closed shell, a d10 system aswell? I was wondering why the linear-response theory works in this case but not for Zn2+. Best regards Dominik Voigt Dominik Voigt PhD Student University of Applied Sciences Münster Department of Physical Chemistry > > Dear Dominik > >> the method you suggested Giuseppe. I don't quite know whats the 'right' >> distance between the valence band and the d-band? Can I use experimental >> data from xps/ups spectra for that matter or do you have other >> suggestions? > > Yes, it is actually what I did with ZnO. As I remarked in my previous > message, it is going to work well if you apply the correction also to > the S 3p shell, in a DFT+U(Zn,S) fashion. In wurtzite ZnO the strong > curvature of the Zn 4s conduction band is such that the CB is > substantially free from delocalization error and it is a good absolute > reference. If you know the position of the Fermi level (which can > depend on intrinsic defects in real samples) with respect to the CB, > then you can reasonably estimate the position of the Zn 3d band. > I hope I've not added entropy... > Best > Giuseppe > > Quoting dv009...@fh-muenster.de: > >> Thanks all for the helpful comments and interesting papers. I'm fine >> correcting the delocalization error of the Zn 3d states 'semiempirical' >> by >> the method you suggested Giuseppe. I don't quite know whats the 'right' >> distance between the valence band and the d-band? Can I use experimental >> data from xps/ups spectra for that matter or do you have other >> suggestions? >> >> Best regards >> >> Dominik Voigt >> >> Dominik Voigt >> PhD Student University of Applied Sciences Münster >> Department of Physical Chemistry >> >> >> >>> Dear All, >>> >>> >>> Giuseppe is right, this is a limitation of the current implementation >>> of >>> the linear-response theory to compute Hubbard parameters for >>> closed-shell >>> systems (like ZnO, ZnS, etc.). This "limitation" is known, and there is >>> some comment about this in q-e/HP/Doc/README. Please check this paper >>> for >>> more details: >>> <https://aip.scitation.org/doi/10.1063/1.4869718> >>> >>> https://aip.scitation.org/doi/10.1063/1.4869718 >>> >>> >>> The developers of the HP code are planning to investigate this issue in >>> more detail, and hopefully we will come out with some solution in the >>> near >>> future. >>> >>> >>> Best regards, >>> >>> Iurii >>> >>> >>> -- >>> Dr. Iurii Timrov >>> Postdoctoral Researcher >>> STI - IMX - THEOS and NCCR - MARVEL >>> Swiss Federal Institute of Technology Lausanne (EPFL) >>> CH-1015 Lausanne, Switzerland >>> +41 21 69 34 881 >>> http://people.epfl.ch/265334 >>> ________________________________ >>> From: users <users-boun...@lists.quantum-espresso.org> on behalf of >>> Giuseppe Mattioli <giuseppe.matti...@ism.cnr.it> >>> Sent: Monday, June 15, 2020 10:55:59 PM >>> To: Quantum ESPRESSO users Forum >>> Subject: Re: [QE-users] Problems with hp.x >>> >>> >>> Dear Dominik >>> I suppose that the problem is not in hp.x, but in the application of >>> the linear-response method itself to Zn(2+). Zn(2+) is a d10 >>> transition metal, with the 3d band fully occupied. In ZnO, e.g., the >>> Zn 3d band is quite narrow and placed below the O 2p valence band, and >>> I suppose that the same holds for ZnS, with the Zn 3d band pushing up >>> the S 3p band. When you apply the LR method to Zn, you compute >>> quantities such as d(alpha)/dn, where alpha is the (small) >>> perturbation and n is the occupation number of d orbitals on site I >>> (see International Journal of Quantum Chemistry 2014, 114, 14 for >>> details). If the shell is full, then you can perturb whatever you want >>> but you will never obtain more than the full occupation of the shell >>> that you already have in the unperturbed system. This is likely the >>> reason for the crazy values of LR U you obtain. If you want to correct >>> the strong delocalization error of the Zn 3d narrow band within the >>> DFT+U formalism, then you must use a "semiempirical" approach, >>> choosing, e.g., the U value that places the Zn 3d shell at the correct >>> distance from the valence band maximum. In this case, I would >>> recommend the use of a second +U correction on the S 3p shell, which >>> should ensure a good recovery of the ZnS band gap. I've satisfactorily >>> used this scheme in the case of ZnO in several publications, from >>> which you may want to take inspiration (Adv. Energy Mater. 2014, 4, >>> 1301694). >>> HTH >>> Giuseppe >>> >>> Quoting dv009...@fh-muenster.de: >>> >>>> Hello everyone, >>>> >>>> I'm trying to calculate the hubbard u parameter for Zn in Zinc sulfide >>>> (sphalerite structure) with the help of the hp.x code. The >>>> calculations >>>> terminate normally without any errors. The problem is that I get >>>> (presumably) way too high values for U that also won't converge (if I >>>> take >>>> the value I got from a one-shot calculation and plug it in the SCF >>>> input >>>> and then redo the HP calculation). >>>> >>>> For example in the first step I calculate a U = 75.7035 in the second >>>> iteration I get U = 804.2405 and in the third U = 30999.2684. >>>> >>>> This seems unreasonable considering that the calculations for the >>>> provided >>>> examples in the 'HP' folder work fine and converge fast without such a >>>> massive change to a certain value for U using the above described >>>> scheme. >>>> >>>> Has someone an idea what is causing this trouble in my system? I >>>> already >>>> tried different PPs, functionals, U_projection_type, thresholds and k >>>> and >>>> q point grids all without success. >>>> >>>> Below is my input for the scf and hp calculation >>>> >>>> SCF-input: >>>>  &control >>>> calculation='scf' >>>> restart_mode='from_scratch', >>>> pseudo_dir = '/home/dominik/codes/QE6.5/pseudo/' >>>> outdir='/home/dominik/codes/QE6.5/tempdir/' >>>> prefix='zns' >>>> / >>>> &SYSTEM >>>> ibrav = 2 >>>> celldm(1)=10.291937439 >>>> nat = 2 >>>> ntyp = 2 >>>> ecutwfc = 60.0 >>>> ecutrho= 720.0 >>>> lda_plus_u = .true. >>>> lda_plus_u_kind = 0 >>>> U_projection_type = 'atomic' >>>> Hubbard_U(1) = 1d-8 >>>> / >>>> &electrons >>>> mixing_beta=0.7 >>>> conv_thr=1d-15 >>>> / >>>> ATOMIC_SPECIES >>>> Zn 65.39 Zn.pbe-dn-rrkjus_psl.0.2.2.UPF >>>> S 32.07 S.pbe-n-rrkjus_psl.0.1.UPF >>>> ATOMIC_POSITIONS {alat} >>>> Zn 0.000000 0.000000 0.000000 >>>> S 0.250000 0.250000 0.250000 >>>> K_POINTS automatic >>>> 12 12 12 0 0 0 >>>> >>>> >>>> HP-input: >>>> &inputhp >>>> prefix='zns' >>>> outdir='/home/dominik/codes/QE6.5/tempdir/' >>>> nq1 = 2 >>>> nq2 = 2 >>>> nq3 = 2 >>>> conv_thr_chi = 1.0d-10 >>>> iverbosity =2 >>>> / >>>> >>>> >>>> Best regards >>>> >>>> >>>> Dominik Voigt >>>> >>>> Dominik Voigt >>>> PhD Student University of Applied Sciences Münster >>>> Department of Physical Chemistry >>>> >>>> _______________________________________________ >>>> Quantum ESPRESSO is supported by MaX >>>> (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>>) >>>> users mailing list users@lists.quantum-espresso.org >>>> https://lists.quantum-espresso.org/mailman/listinfo/users >>> >>> >>> >>> GIUSEPPE MATTIOLI >>> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA >>> Via Salaria Km 29,300 - C.P. 10 >>> I-00015 - Monterotondo Scalo (RM) >>> Mob (*preferred*) +39 373 7305625 >>> Tel + 39 06 90672342 - Fax +39 06 90672316 >>> E-mail: <giuseppe.matti...@ism.cnr.it> >>> >>> _______________________________________________ >>> Quantum ESPRESSO is supported by MaX >>> (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>>) >>> users mailing list users@lists.quantum-espresso.org >>> https://lists.quantum-espresso.org/mailman/listinfo/users >>> _______________________________________________ >>> Quantum ESPRESSO is supported by MaX >>> (www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso>) >>> users mailing list users@lists.quantum-espresso.org >>> https://lists.quantum-espresso.org/mailman/listinfo/users >> >> >> _______________________________________________ >> Quantum ESPRESSO is supported by MaX >> (www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso>) >> users mailing list users@lists.quantum-espresso.org >> https://lists.quantum-espresso.org/mailman/listinfo/users > > > > GIUSEPPE MATTIOLI > CNR - ISTITUTO DI STRUTTURA DELLA MATERIA > Via Salaria Km 29,300 - C.P. 10 > I-00015 - Monterotondo Scalo (RM) > Mob (*preferred*) +39 373 7305625 > Tel + 39 06 90672342 - Fax +39 06 90672316 > E-mail: <giuseppe.matti...@ism.cnr.it> > > _______________________________________________ > Quantum ESPRESSO is supported by MaX > (www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso>) > users mailing list users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso<http://www.max-centre.eu/quantum-espresso>) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
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