Dear Shreya<div><br></div><div>In none of the optimisation step the wave function optimisation has converged, therefore forces and stress tensor are absolutely unreliable. </div><div>My suggestion is that you first find some good settings that allow the convergence of the single point calculation for the initial structure.</div><div><br></div><div>Regards</div><div>Marcella<br><br></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Tuesday, August 16, 2022 at 6:39:35 PM UTC+2 shrsi...@gmail.com wrote:<br/></div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Dear all,<div>I am trying to optimize the crystal structure of carbon nitrideĀ (Unit cell contains 144 atoms: C<font size="1">48</font>H<font size="1">24</font>N<font size="1">72</font>). I have tried various suggestions for Basis sets (SZV, DZVP, TZVP), optimization method (CG BFGS, L-BFGS) but cell-optimization is not converging. Energy is highly fluctuating, ultimately forces on a set of atoms become very high and pressure deviation huge. The initial structure is already optimized in FHI-AIMS, and taken from a reference (<a href="https://pubs.acs.org/doi/full/10.1021/acs.chemmater.7b00965" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=en&q=https://pubs.acs.org/doi/full/10.1021/acs.chemmater.7b00965&source=gmail&ust=1660754526451000&usg=AOvVaw2LFlqNeVNMNCyAEsP3pdC7">https://pubs.acs.org/doi/full/10.1021/acs.chemmater.7b00965</a>).</div><div>Particularly, I noticed very high forces on Nitrogen atoms that are involved in Hydrogen-bonding (see attached image of before and after structure)</div><div>I have attached one of the CP2K input file, initial geometry and output file for your reference.</div><div>Thanks in advance.</div><div>Shreya</div><div>Email: <a href data-email-masked rel="nofollow">shrsi...@gmail.com</a></div><div><br></div></blockquote></div>
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