<div>Hello, <br /></div><div>Your wavefunction seems close to convergence but is trailing when convergence fails. I would suggest using a inner SCF loop (20 to 50 iter) and an outer scf loop (5 to 20 iter) https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/SCF/OUTER_SCF.html</div><div>At the end of each inner loop, the preconditionner will be used again to provide a wavefunction that should converge more smoothly. However, convergence with diffuse functions can be complicated. You could try removing them from the lightest atoms (H), it could tremendously improve convergence if it proves too tricky, it should not generally impact your results much.</div><div>You could also use extrapolation which could help improve MD stability (ASPC for instance: https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/QS.html#CP2K_INPUT.FORCE_EVAL.DFT.QS.EXTRAPOLATION).</div><div>Last piece of advice would be to reduce the cell size as larger cells require larger plane-waves basis sets, which can prove costly while not improving the quality of your results.</div><div>Do keep in mind that DFT sometimes fail when dealing with complicated charge-separation situations where multireference character becomes important.</div><div>I hope this will help, take care, <br /></div><div>Quentin</div><div class="gmail_quote"><div dir="auto" class="gmail_attr">Le vendredi 7 mars 2025 à 01:21:04 UTC+1, Nicholas Laws a écrit :<br/></div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Hi CP2K Community,<div><br></div><div>I hope this message finds you well. I am trying to perform a high energy collision of a fast incident neutral (EMI-BF4), which is composed of a cation (EMI+) and an anion (BF4-), and a surface. The "surface" is modeled as a harmonic potential set 10 Å away from the EMI-BF4 neutral. The EMI-BF4 neutral travels into the harmonic potential at 70 eV, but begins to exhibit energy instabilities approximately 150 MD steps following collision. As a result, the fragmented species do not continue to propagate and equilibrate as expected. In my setup, I use the wB97X-D functional, an aug-cc-pVTZ basis set (chosen specifically for its diffuse functions to better describe the negative charge distribution and long-range interactions of BF4-), and all-electron potentials. To address the observed convergence issues, I have tried:</div><ol><li>Switching to DIAGONALIZATION in the SCF</li><li>Increasing the number of added MOs (ADDED_MOS)</li><li>Experimented with MIXING (Broyden) parameters</li></ol>yet the SCF still struggles to converge reliably beyond the collision event. My goal is to obtain precise atomic partial charges on the post-collision fragments, ideally showing near-integer formal charges that reveal how the original cation and anion charges are redistributed.<br><br><div>I was curious if the community could suggest additional strategies or settings within CP2K that might stabilize the SCF convergence under these conditions? I’ve attached my input, output, and trajectory files in hopes that they clarify the nature of the instabilities.<br><br>Thank you very much for any guidance you can provide, and please let me know if there is any further information I can supply.<div><br></div><div>All my best,</div><div>Nick</div></div></blockquote></div>
<p></p>
-- <br />
You received this message because you are subscribed to the Google Groups "cp2k" group.<br />
To unsubscribe from this group and stop receiving emails from it, send an email to <a href="mailto:cp2k+unsubscribe@googlegroups.com">cp2k+unsubscribe@googlegroups.com</a>.<br />
To view this discussion visit <a href="https://groups.google.com/d/msgid/cp2k/738f62c5-b1bf-4dea-b025-4e9e8310079dn%40googlegroups.com?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/738f62c5-b1bf-4dea-b025-4e9e8310079dn%40googlegroups.com</a>.<br />