<div dir="ltr"><div style="unicode-bidi:plaintext">Dear Xie,</div><div style="unicode-bidi:plaintext"><br></div><div style="unicode-bidi:plaintext">On Wed, 2025-12-17 at 10:56 +0800, 谢征奥 wrote:</div><blockquote type="cite" class="evo-awrap" style="margin-top:0em;margin-bottom:0em;color:rgb(115,115,115)"><div style="unicode-bidi:plaintext;line-height:1.7;font-size:14px;font-family:Arial"><div style="unicode-bidi:plaintext;margin:0px"><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px;font-size:16px;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Helvetica,Arial,sans-serif"><span style="color:rgba(0,0,0,0.85)">Dear QE Community,</span></div><div class="gmail-container-Uxvbjy gmail-md-box-line-break gmail-wrapper-GYqxgQ gmail-undefined" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:20px 0px 0px;padding:0px;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Helvetica,Arial,sans-serif;font-size:16px"><br></div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px;font-size:16px;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Helvetica,Arial,sans-serif">I hope you are having a productive day and that your research commitments are not overly demanding. Allow me to introduce myself: I am Xie, a Chinese researcher, and I am new to using <span style="outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;font-weight:700;line-height:28px">QE (Quantum ESPRESSO)</span>. I have a strong interest in computational physics, which has led me to deepen my application of this software for my research projects. I am writing today to ask three specific questions regarding the calculations I am conducting, as I have encountered some difficulties and greatly value your expertise and extraordinary experience in the field of QE, given that you are one of the core developers of the software.</div><div class="gmail-container-Uxvbjy gmail-md-box-line-break gmail-wrapper-GYqxgQ gmail-undefined" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:20px 0px 0px;padding:0px;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Helvetica,Arial,sans-serif;font-size:16px"><br></div><ol class="gmail-auto-hide-last-sibling-br" style="margin:0px 0px 8px;outline:currentcolor;box-sizing:border-box;border:0px solid;padding:0px 0px 0px 24px;list-style:none;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Helvetica,Arial,sans-serif;font-size:16px"><li style="outline:currentcolor;box-sizing:border-box;border:0px solid;margin:8px 0px;padding:0px;line-height:24px;list-style-type:decimal"><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px">When performing phonon spectrum calculations with QE, what is the correct sequence of steps for structural relaxation? Should I first run a <code style="margin:0px;outline:currentcolor;box-sizing:border-box;border:0px rgba(0,0,0,0.85);padding:0px 4px;font-family:Menlo,Monaco,Consolas,"Courier New",monospace;font-feature-settings:normal;background:0% 0% repeat rgba(0,0,0,0.06);border-radius:4px;line-height:28px;color:rgba(0,0,0,0.85)">vc-relax</code> calculation, then increase the force and energy convergence thresholds before performing a subsequent <code style="margin:0px;outline:currentcolor;box-sizing:border-box;border:0px rgba(0,0,0,0.85);padding:0px 4px;font-family:Menlo,Monaco,Consolas,"Courier New",monospace;font-feature-settings:normal;background:0% 0% repeat rgba(0,0,0,0.06);border-radius:4px;line-height:28px;color:rgba(0,0,0,0.85)">relax</code> calculation? Or is it sufficient to verify the convergence of the total stress from the <code style="margin:0px;outline:currentcolor;box-sizing:border-box;border:0px rgba(0,0,0,0.85);padding:0px 4px;font-family:Menlo,Monaco,Consolas,"Courier New",monospace;font-feature-settings:normal;background:0% 0% repeat rgba(0,0,0,0.06);border-radius:4px;line-height:28px;color:rgba(0,0,0,0.85)">vc-relax</code> results and use them directly for subsequent calculations? In my case, the pressure obtained from <code style="margin:0px;outline:currentcolor;box-sizing:border-box;border:0px rgba(0,0,0,0.85);padding:0px 4px;font-family:Menlo,Monaco,Consolas,"Courier New",monospace;font-feature-settings:normal;background:0% 0% repeat rgba(0,0,0,0.06);border-radius:4px;line-height:28px;color:rgba(0,0,0,0.85)">vc-relax</code> has met my convergence criteria, but when I used the optimized structure to run a <code style="margin:0px;outline:currentcolor;box-sizing:border-box;border:0px rgba(0,0,0,0.85);padding:0px 4px;font-family:Menlo,Monaco,Consolas,"Courier New",monospace;font-feature-settings:normal;background:0% 0% repeat rgba(0,0,0,0.06);border-radius:4px;line-height:28px;color:rgba(0,0,0,0.85)">relax</code> calculation, the pressure value became significantly higher: is this a reasonable behavior?</div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px"><br></div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px">A well converged vc-relax calculation should be enough. Recent QE versions make a final SCF calculation at the end to check for forces and pressures in the relaxed structure. If pressure (absolute value) is higher than, say, 0.5 kbar, run a second vc-relax calculation starting with the previously relaxed structure. </div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px"><br></div></li><li style="outline:currentcolor;box-sizing:border-box;border:0px solid;margin:8px 0px;padding:0px;line-height:24px;list-style-type:decimal"><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px">When using the <code style="margin:0px;outline:currentcolor;box-sizing:border-box;border:0px rgba(0,0,0,0.85);padding:0px 4px;font-family:Menlo,Monaco,Consolas,"Courier New",monospace;font-feature-settings:normal;background:0% 0% repeat rgba(0,0,0,0.06);border-radius:4px;line-height:28px;color:rgba(0,0,0,0.85)">pw.x</code> module, which parameters have a significant impact on eliminating imaginary frequencies?</div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px"><br></div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px">Convergence criteria for forces on atoms may be stricter than usual to avoid imaginary frequencies. As always, check for convergen w.r.t. ecutwfc and k-points grid.</div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px"><br></div></li><li style="outline:currentcolor;box-sizing:border-box;border:0px solid;margin:8px 0px;padding:0px;line-height:24px;list-style-type:decimal"><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px">During the structural optimization process, is it acceptable to always use the parameter <code style="margin:0px;outline:currentcolor;box-sizing:border-box;border:0px rgba(0,0,0,0.85);padding:0px 4px;font-family:Menlo,Monaco,Consolas,"Courier New",monospace;font-feature-settings:normal;background:0% 0% repeat rgba(0,0,0,0.06);border-radius:4px;line-height:28px;color:rgba(0,0,0,0.85)">ibrav=0</code> in the <code style="margin:0px;outline:currentcolor;box-sizing:border-box;border:0px rgba(0,0,0,0.85);padding:0px 4px;font-family:Menlo,Monaco,Consolas,"Courier New",monospace;font-feature-settings:normal;background:0% 0% repeat rgba(0,0,0,0.06);border-radius:4px;line-height:28px;color:rgba(0,0,0,0.85)"><a href="http://relax.in">relax.in</a></code> input file?</div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px"><br></div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px">It is advisable to use ibrav according to the actual Bravais lattice of the compound you are calculating.</div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px"><br></div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px">Hope this helps!</div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px">Claudio</div></li></ol><div class="gmail-container-Uxvbjy gmail-md-box-line-break gmail-wrapper-GYqxgQ gmail-undefined" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:20px 0px 0px;padding:0px;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Helvetica,Arial,sans-serif;font-size:16px"><br></div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px;font-size:16px;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Helvetica,Arial,sans-serif">Thank you in advance for the time you will dedicate to my questions and for your valuable guidance. As a novice in QE, every suggestion will be fundamental to advancing my learning journey and ensuring the success of my calculations. If you require any further details about my input files or the results obtained, I would be happy to provide all the necessary information.</div><div class="gmail-container-Uxvbjy gmail-md-box-line-break gmail-wrapper-GYqxgQ gmail-undefined" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:20px 0px 0px;padding:0px;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Helvetica,Arial,sans-serif;font-size:16px"><br></div><div class="gmail-auto-hide-last-sibling-br gmail-paragraph-pP9ZLC gmail-paragraph-element gmail-br-paragraph-space" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:0px;padding:0px;line-height:24px;font-size:16px;font-family:Inter,-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Helvetica Neue",Helvetica,Arial,sans-serif">Sincerely,<div class="gmail-container-Uxvbjy gmail-md-box-line-break gmail-wrapper-GYqxgQ gmail-undefined" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:20px 0px 0px;padding:0px"><br></div>Xie<div class="gmail-container-Uxvbjy gmail-md-box-line-break gmail-wrapper-GYqxgQ gmail-undefined" style="unicode-bidi:plaintext;outline:currentcolor;box-sizing:border-box;border:0px solid;margin:20px 0px 0px;padding:0px"><br></div>Chinese Researcher</div><br></div></div><div style="unicode-bidi:plaintext"><br></div><div style="unicode-bidi:plaintext">_______________________________________________________________________________<br></div><div style="unicode-bidi:plaintext">The Quantum ESPRESSO Foundation stands in solidarity with all civilians worldwide who are victims of terrorism, military aggression, and indiscriminate warfare.<br></div><div style="unicode-bidi:plaintext">--------------------------------------------------------------------------------<br></div><div style="unicode-bidi:plaintext">Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/" title="Click to open http://www.max-centre.eu/">www.max-centre.eu</a>)<br></div><div style="unicode-bidi:plaintext">users mailing list<span class="gmail-Apple-converted-space"> </span><a href="mailto:users@lists.quantum-espresso.org" title="Click to mail users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a><br></div><div style="unicode-bidi:plaintext"><a href="https://lists.quantum-espresso.org/mailman/listinfo/users" title="Click to open https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a></div></blockquote><div style="unicode-bidi:plaintext"><br></div><div style="unicode-bidi:plaintext"><span style="color:rgb(0,0,0);font-family:Cantarell;font-size:14.6667px"><pre style="margin:0px">-- <br></pre><div style="unicode-bidi:plaintext"><font face="Lucida Sans Unicode, Lucida Grande, sans-serif" size="4">Claudio A. Perottoni</font></div><div style="unicode-bidi:plaintext"><font face="Lucida Sans Unicode, Lucida Grande, sans-serif">Universidade de Caxias do Sul</font></div><div style="unicode-bidi:plaintext"><font face="Lucida Sans Unicode, Lucida Grande, sans-serif">95070-560 Caxias do Sul - RS - Brazil</font></div><div style="unicode-bidi:plaintext"><a href="https://orcid.org/0000-0002-8425-845X" title="Click to open https://orcid.org/0000-0002-8425-845X"><font face="Lucida Sans Unicode, Lucida Grande, sans-serif">https://orcid.org/0000-0002-8425-845X</font></a></div></span></div><br class="gmail-Apple-interchange-newline"></div>

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