<p>Hi Ralf,</p>
<p>the density matrix-based screening of the derivatives was only
removed in the special case of response forces (RPA, MP2, TDDFT, EC). Standard HFX
calculations still use it by default. Note, however, that the default
value of EPS_SCHWARZ_FORCES was changed to 100 x EPS_SCHWARZ (vs 1.0E-6
originally), in order to keep the accuracy of the derivatives consistent
with that of of the integrals.</p>
<p>Best,</p>
<p>Augustin</p>
<br /><br /><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Friday, 10 January 2025 at 13:49:42 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>Thanks for the quick and comprehensive reply.</div><div><br></div><div>Is
the density matrix-based derivative integral screening still in place
for "standard" HFX calculations (i.e. non-response type), or is the
screening also <br></div><div>removed here? This should then have an effect on how to properly choose the EPS_SCHWARZ_FORCES threshold in relation to EPS_SCHWARZ?</div><div> <br></div><br><br><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Wednesday, January 8, 2025 at 10:35:06 AM UTC+1 Augustin Bussy 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"><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" rel="nofollow" target="_blank" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://github.com/cp2k/cp2k/commit/233cc0496608329821996a6a19a46b58c16292f1%23diff-e05447976b45d06ff57c2ca772d89269da230e4970b6001c4ee2f25c70584cffR428-R430&source=gmail&ust=1736600998838000&usg=AOvVaw0FR-rTIC2eo6CTiIi15fb9">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></blockquote></div></blockquote></div>
<p></p>
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