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<div>Dear Sitangshu</div>
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<div>You should have a look at the example (in PP) on how to use the FT to extract the magnetic anisotropy energy and its orbital/site decomposition. FT ca be applied to insulators as well as metals.<br>
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<div><a href="https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.205409" target="_blank">https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.205409</a>
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<div><a href="https://iopscience.iop.org/article/10.1088/1367-2630/ab3060/pdf" target="_blank">https://iopscience.iop.org/article/10.1088/1367-2630/ab3060/pdf</a></div>
<div><a href="https://arxiv.org/abs/1907.04532" target="_blank">https://arxiv.org/abs/1907.04532</a></div>
<div><a href="https://journals.aps.org/prb/abstract/10.1103/PhysRevB.93.144405" target="_blank">https://journals.aps.org/prb/abstract/10.1103/PhysRevB.93.144405</a></div>
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<div>You should 1st perform a scf collinear calculation and then two nscf non-collinear (+SOC) calculations starting from previous scf. Then use projwfc (with correct input) to extract the MAE and site/orbital decomposition.<br>
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<div>best<br>
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<div>Cyrille</div>
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<div>ps: use recent versions of pw (>6.2)<br>
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<div style="font-family:Tahoma; font-size:13px"><b>Cyrille Barreteau</b><br>
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<div id="divRpF497701" style="direction: ltr;"><font size="2" face="Tahoma" color="#000000"><b>De :</b> users [users-bounces@lists.quantum-espresso.org] de la part de Sitangshu Bhattacharya [sitangshu@iiita.ac.in]<br>
<b>Envoyé :</b> dimanche 10 novembre 2019 08:30<br>
<b>À :</b> Quantum Espresso users Forum<br>
<b>Objet :</b> Re: [QE-users] Magnetic anisotropy energy in magnetic insulators<br>
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<div>Sorry for the typo: I meant a "collinear". And the cell consist of two same atoms.</div>
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<div>Regards,</div>
<div>Sitangshu<br>
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<div dir="ltr" class="gmail_attr">On Sun, Nov 10, 2019 at 5:22 AM Sitangshu Bhattacharya <<a href="mailto:sitangshu@iiita.ac.in" target="_blank" rel="noopener noreferrer">sitangshu@iiita.ac.in</a>> wrote:<br>
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<div>Dear QEusers,</div>
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<div>Recently, I came across the force theorem concept (Phys. Rev. B 90, 205409 (2014)) to determine the magnetic anisotropy energy (MAE) in magnetic metals. After a basic understanding of the physics and workflow for magnetic metals, I tried to execute the
same for magnetic insulators (with a gap). I am bit confused here as the workflow process is not mentioned clearly anywhere (after googling tons of links in user-list) for magnetic insulators.</div>
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<div>So, here the problem is: I have constructed a reduced dimensional crystal with incomplete p orbitals. The cell has two atoms. I am expecting a strong MAE as I have checked that the crystal is found to possess a strong SOC.</div>
<div>So the first step: I did a non-collinear and non-spin orbit computation using a scalar relativistic pseudo to figure out the spin polarized charge densities. Now here is the problem.<br>
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<div>The input snippet, I used is:<br>
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<div> &system<br>
nspin = 2<br>
tot_magnetization=3<br>
occupations='smearing'<br>
smearing='marzari-vanderbilt'<br>
degauss=0.005<br>
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<div> </div>
<div>The out snippet at the end is obtained as<br>
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total magnetization = 3.00 Bohr mag/cell<br>
<div> absolute magnetization = 3.01 Bohr mag/cell</div>
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<div> Magnetic moment per site:<br>
atom: 1 charge: 12.7978 magn: 0.6984 constr: 0.0000<br>
atom: 2 charge: 12.7978 magn: 0.6984 constr: 0.0000<br>
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<div>Is this the correct flow to get the charge density for magnetic insuators? Interestingly,
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<div>1) The good news is that the above calculation converges!</div>
<div>But,<br>
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<div>2) The moments changes if I change tot_magnetization=1. <br>
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<div>2) If I use starting_magnetization(1) = say 1, then at the end, the magnetization and moments are converged to zero with occupation=smearing.
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<div>4) If I use occupations=fixed, the charge densities are not properly calculated and produces error in the HOMO LUMO energy positions.<br>
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<div>I am clueless to what is happening! I would be glad for any response!<br>
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<div>With regards,</div>
<div>Sitangshu Bhattacharya</div>
<div>IIIT-Allahabad, India<br>
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<div><font size="3">Sitangshu Bhattacharya (সিতাংশু ভট্টাচার্য), Ph.D<br>
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<div><font size="3">Assistant Professor,</font></div>
<div><font size="3">Room No. 2221, CC-1,<br>
Nanoscale Electro-Thermal Laboratory,<br>
Department of Electronics and Communication Engineering,<br>
Indian Institute of Information Technology-Allahabad<br>
</font></div>
<font size="3"><span>Uttar Pradesh 211 012</span><br>
India<br>
Telephone: 91-532-2922000 Extn.: 2131<br>
Web-page: <a href="http://profile.iiita.ac.in/sitangshu/" target="_blank" rel="noopener noreferrer">
http://profile.iiita.ac.in/sitangshu/</a><br>
Institute: <a href="http://www.iiita.ac.in/" target="_blank" rel="noopener noreferrer">
http://www.iiita.ac.in/</a><br>
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<div><font size="3">**********************************************</font></div>
<div><font size="3">Sitangshu Bhattacharya (সিতাংশু ভট্টাচার্য), Ph.D<br>
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<div><font size="3">Assistant Professor,</font></div>
<div><font size="3">Room No. 2221, CC-1,<br>
Nanoscale Electro-Thermal Laboratory,<br>
Department of Electronics and Communication Engineering,<br>
Indian Institute of Information Technology-Allahabad<br>
</font></div>
<font size="3"><span>Uttar Pradesh 211 012</span><br>
India<br>
Telephone: 91-532-2922000 Extn.: 2131<br>
Web-page: <a href="http://profile.iiita.ac.in/sitangshu/" target="_blank" rel="noopener noreferrer">
http://profile.iiita.ac.in/sitangshu/</a><br>
Institute: <a href="http://www.iiita.ac.in/" target="_blank" rel="noopener noreferrer">
http://www.iiita.ac.in/</a><br>
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