<div dir="ltr"><div>Dear Michele,</div><div><br></div><div>I have had the time for just a quick inspection to your files, and unfortunately I did not find possible mistakes.</div><div>Maybe someone else will be more helpful in this regard.</div><div>Both the total energy and the total force in the output are monotonically decreasing, with the exception of the</div><div>4th relaxation step.</div><div>The only thing that might be odd (but it could be correct for the system you're studying) is that the</div><div>comparison of the initial and the latest structure shows only an outwards relaxation of the topmost and lowest atomic</div><div>layers.</div><div><br></div><div>I can just suggest at the moment to restart from scratch a calculation in which you use as initial</div><div>positions the latest (or the ones before the latest) printed by the code. It shouldn't change anything in principle, but</div><div>there have been several cases in my experience in which that properly worked, as if at some point of the structural optimization the</div><div>starting charge density were for some reason "wrong" or "inappropriate" (even if coming from the previous steps), and</div><div>restarting from atomic/random wave functions prevents the code from remaining stuck. However, I don't have a clear explanation for that</div><div>if not that this recipe has worked for me! </div><div><br></div><div>Giovanni</div><div><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><span style="color:rgb(0,0,0)">-- <br><br>Giovanni Cantele, PhD<br>CNR-SPIN<br>c/o Dipartimento di Fisica<br>Universita' di Napoli "Federico II"<br>Complesso Universitario M. S. Angelo - Ed. 6<br>Via Cintia, I-80126, Napoli, Italy<br><a href="mailto:giovanni.cantele@spin.cnr.it" style="color:rgb(17,85,204)" target="_blank">e-mail: giovanni.cantele@spin.cnr.it</a><br>Phone: +39 081 676910<br>Skype contact: giocan74<br><br>ResearcherID: <a href="http://www.researcherid.com/rid/A-1951-2009" style="color:rgb(17,85,204)" target="_blank">http://www.researcherid.com/rid/A-1951-2009</a><br>Web page: </span><a href="https://sites.google.com/view/giovanni-cantele/home" style="color:rgb(17,85,204)" target="_blank">https://sites.google.com/view/giovanni-cantele/home</a><br></div></div></div><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Il giorno mer 28 mag 2025 alle ore 11:23 michele de angelis <<a href="mailto:michele.deangelis.01@alumni.uniroma2.eu" target="_blank">michele.deangelis.01@alumni.uniroma2.eu</a>> ha scritto:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>
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<div><span style="display:inline-block;color:inherit;background-color:inherit"><span><a href="https://uniroma2-my.sharepoint.com/:u:/g/personal/michele_deangelis_01_alumni_uniroma2_eu/EdqwsiZzdStJhJGXaYDSIOsB0WUkus6riva9xFNK4dvGrw" rel="noopener noreferrer" id="m_-8699256268834698392m_-5147110039627218552OLK_Beautified_f3f625cc-4151-b062-5f0d-33ab838e113e" style="padding:0px 1px;border-radius:2px;background-color:rgb(244,244,244)" target="_blank"><img alt="" role="presentation" style="width: 16px; height: 16px; vertical-align: middle; padding: 1px 2px 2px 0px;" src="https://res-1.cdn.office.net/assets/mail/file-icon/png/generic_16x16.png">YBCO_001_CuO2_2layers.in</a></span></span></div>
<div><span style="display:inline-block;color:inherit;background-color:inherit"><span><a href="https://uniroma2-my.sharepoint.com/:u:/g/personal/michele_deangelis_01_alumni_uniroma2_eu/EWwLUiRWxFxLiOe-okzTGBkBJ5sQt7QCPbjEqCaKYWBDQA" rel="noopener noreferrer" id="m_-8699256268834698392m_-5147110039627218552OLK_Beautified_df1ee638-15e6-3947-7aa2-dec57e641b00" style="padding:0px 1px;border-radius:2px;background-color:rgb(244,244,244)" target="_blank"><img alt="" role="presentation" style="width: 16px; height: 16px; vertical-align: middle; padding: 1px 2px 2px 0px;" src="https://res-1.cdn.office.net/assets/mail/file-icon/png/generic_16x16.png">YBCO_001_CuO2_2layers.out</a></span></span></div>
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Dear all,<br>
I am trying to relax YBCO (001) slabs with symmetric terminations (same on both sides) and a vacuum spacing of 7.5 Å on each side (7.5 Å – slab – 7.5 Å). I have tested all four possible surface terminations of YBCO, but none of the relaxations converge properly.
After m SCF cycles and n BFGS cycles, the SCF calculation starts to exceed 100 iterations.<br>
Moreover, the total energy values reported in the output file do not show a monotonic trend but oscillate instead. In contrast, the total force does decrease, from 0.9 down to about 0.09. I am using PBE-PAW pseudopotentials with the GGA approximation. The initial
geometry has been carefully verified.<br>
Spin and polarization effects are not included, as the slabs are symmetric. I have attempted several adjustments to improve convergence, including:<br>
- Reducing mixing_beta to 0.1</div>
<div style="text-align:left;text-indent:0px;background-color:rgb(255,255,255);margin:0px;font-size:15px;color:rgb(0,0,0)">
- Increasing degauss to 0.05 and changing the smearing type<br>
- Setting mixing_mode = 'local-TF'<br>
- Switching the diagonalization method to cg</div>
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<br>
However, the problem persists.<br>
Could you kindly help me understand what might be going wrong? My input and output files are attached below for reference.<br>
Thank you in advance for your support.</div>
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Best regards, </div>
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<div style="text-align:left;text-indent:0px;background-color:rgb(255,255,255);margin:0px;font-size:15px;color:rgb(0,0,0)">
Michele De Angelis </div>
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PhD student, Dept. of Chemical Sciences and Technologies, Univesity of Rome Tor Vergata (Italy)</div>
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