Dear Yuvam Bhateja,
> I am also simulating the same AFM Mott insulator. > For structural optimization I usually use occupation="smearing" and > smearing="Gaussian". > Is it the correct way or should I choose different options. That is fine. You can use also other smearing options, but in any case since your system has a gap and you use the smearing then your system is considered as a fake metal. So the type of smearing does not really matter for magnetic insulators. For magnetic insulators, smearing is needed only for technical reasons: in order to use starting_magnetization, the PW code requires smearing. But once the calculation is converged, you can perform a second SCF calculation with fixed occupations and by setting total magnetization and starting from the previous converged SCF calculation (reading wavefunctions and density/potential). After this second SCF, you will have a magnetic insulator with no smearing. After this you can perform various linear response calculations (PH, HP, etc.). But for DOS you do not need to play this trick with two SCF calculations. One SCF (the first one) is already enough. Then you can compute DOS using the tetrahedron method or with the smearing if you want. Greetings, 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 Yuvam Bhateja <yuvam...@gmail.com> Sent: Friday, August 14, 2020 9:41:58 PM To: Quantum ESPRESSO users Forum Subject: Re: [QE-users] Regarding "occupations" keyword in input file Hello, I had the same question actually. I am also simulating the same AFM Mott insulator. For structural optimization I usually use occupation="smearing" and smearing="Gaussian". Is it the correct way or should I choose different options. And during DOS I use occupation="tetrahedra" with the relaxed calculation. Please guide me with this problem. Regards Yuvam Bhateja IIEST Shibpur India On Fri, 14 Aug 2020, 3:49 pm Matteo Cococcioni, <matteo.cococci...@unipv.it<mailto:matteo.cococci...@unipv.it>> wrote: In addition to what Iurii says, if you use occupation="smearing" the phonon code will assume your system is metallic and will never compute the dielectric tensor and Born effective charge which you need, instead to get the LO-TO splittings at Gamma (non analytic part of the dynamical matrix). Greetings, Matteo Il giorno gio 13 ago 2020 alle ore 20:11 Timrov Iurii <iurii.tim...@epfl.ch<mailto:iurii.tim...@epfl.ch>> ha scritto: Dear Mohaddeseh, To perform linear response calculations (phonons, calculation of Hubbard parameters, etc.) for magnetic insulators, I use the procedure described in q-e/HP/examples/example02/README. If you have a gapped system, you should not use smearing, because there can be numerical issues (due to the division by zero, because the DOS at the Fermi level can be very small using small smearing for insulators, see Eq. (79) in Rev. Mod. Phys. 73, 515 (2001)). Greetings, 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<mailto:users-boun...@lists.quantum-espresso.org>> on behalf of Mohad Abbasnejad <mohaddeseh.abbasne...@gmail.com<mailto:mohaddeseh.abbasne...@gmail.com>> Sent: Thursday, August 13, 2020 7:58:21 PM To: users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> Subject: [QE-users] Regarding "occupations" keyword in input file Dear QE users, Hello I have a general question. My structure is Mott hubbard and has a band gap of about 2 eV. It is also antiferromagnetic in its ground state. I can obtain antiferromagnetic state and the desired band gap with hubbard parameters by both ways: occupations: smearing occupations: fixed A) I am wondering whether these occupations can have effect on the phonon frequencies? B) When is it preferable to use occupation fixed in our calculations? Any help would be appreciated. Thanks in advance. Regards, Mohaddeseh -- --------------------------------------------------------- Mohaddeseh Abbasnejad, Assistant Professor of Physics, Faculty of Physics, Shahid Bahonar University of Kerman, Kerman, Iran P.O. Box 76169-133 Tel: +98 34 31322199 Fax: +98 34 33257434 Cellphone: +98 917 731 7514 E-Mail: mohaddeseh.abbasne...@gmail.com<mailto:mohaddeseh.abbasne...@gmail.com> Website: academicstaff.uk.ac.ir/moabbasnejad<http://academicstaff.uk.ac.ir/moabbasnejad> --------------------------------------------------------- _______________________________________________ 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<mailto:users@lists.quantum-espresso.org> https://lists.quantum-espresso.org/mailman/listinfo/users -- Matteo Cococcioni Department of Physics University of Pavia Via Bassi 6, I-27100 Pavia, Italy tel +39-0382-987485 e-mail matteo.cococci...@unipv.it<mailto:lucio.andre...@unipv.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<mailto:users@lists.quantum-espresso.org> https://lists.quantum-espresso.org/mailman/listinfo/users
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