<p>Hi Ralf,</p>
<p>I believe this comes from a bug fix in HFX response forces:
<a href="https://github.com/cp2k/cp2k/commit/233cc0496608329821996a6a19a46b58c16292f1#diff-e05447976b45d06ff57c2ca772d89269da230e4970b6001c4ee2f25c70584cffR428-R430">https://github.com/cp2k/cp2k/commit/233cc0496608329821996a6a19a46b58c16292f1#diff-e05447976b45d06ff57c2ca772d89269da230e4970b6001c4ee2f25c70584cffR428-R430</a>.
Before that, by default, the density matrix was used to screen the
integral derivative, also for response forces. This is not a safe
assumption, and it was therefore removed.</p>
<p>To verify this hypothesis, you can try running CP2K v2024.1 with
the added keyword <span><span>SCREEN_P_FORCES set to FALSE in the HFX%SCREENING
section. This should make the 2 runs equally slow.</span></span></p>
<p><span><span>Best,</span></span></p>
<p><span><span>Augustin</span></span></p><br /><br /><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Wednesday, 8 January 2025 at 10:09:31 UTC+1 Ralf Frischmann 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;"><div>Dear all,</div><div><br></div><div>when running a DCDFT calculation with pre-compiled CP2K binaries from GitHub, I do observe a significant reduction in overall runtime performance when moving from CP2K version 2024.1 to 2024.2 (and versions beyond). </div><div><br></div><div>The increase occurs in ENERGY_FORCE runs only. The crucial spot seems to be the execution part AFTER convergence of the gradient response solver "The linear solver converged in 7 iterations." <br></div><div><br></div><div>From the HFX_MEM_INFO output, it is apparent that version 2024.2 computes a somewhat larger number of "sph. DERIV's calculated on the fly" (see attached outputs for a 20 water PBC cell), but the difference in my opinion is too small to explain the increase in runtime of about 50% for that system size. <br></div><div><br></div><div>For larger system with 32 or 64 H2O molecules, the described runtime increase becomes more pronounced, reaching 250% for 64 H2O molecules.</div><div><br></div><div>Is that expected/intended behavior?<br></div><div><br></div><div>Any explanation, hint or advice would be greatly appreciated.</div><div><br></div><div>Regards,</div><div><br></div><div>Ralf</div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div> <br> </div><div><br></div></blockquote></div>
<p></p>
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