<div>1. EPS_DEFAULT should be increased to at least 1e-10, maybe 1e-12. It does not change the speed of the HF much when you reduce it and creates substantial errors.</div><div>2. Use a PBE restart file and then set SCREEN_ON_INITIAL_P True. This creates very effective screening and rarely causes problems. The initial wave function guess needs to be "good" for this approximation to be valid, but in my experience it is only invalid when one is very far from equilibrium geometries.</div><div>3. For your auxiliary basis set, admm-dzp should already be fairly fast, but if you want to be more aggressive you can use the older cpFIT basis sets. These are less diffuse and will result in quicker HF evaluation.</div><div><br></div><div>Other than that there aren't many ways you can squeeze performance other than changing your SCF section. Are you noticing that you are taking many many SCF steps to converge? Maybe your SCF settings are the problem. I see that you are using diagonalization instead of OT. If you must use traditional diagonalization, that is okay, but I would suggest trying to use some mixing scheme. The default mixing is good for some systems, but in general I find broyden mixing is better. Something like</div><div><br></div><div>&SCF<br> MAX_SCF 100 !DEFAULT 50<br> EPS_SCF 1.0E-5 !DEFAULT 1.0e-5, OT: -6 - -7, FOR DIAG CAN BE SMALLER (DEFAULT)<br> SCF_GUESS RESTART !DEFAULT ATOMIC, RESTART FOR RESTART<br> &DIAGONALIZATION T<br> &END DIAGONALIZATION<br> &MIXING</div><div> METHOD BROYDEN_MIXING</div><div> ALPHA .01</div><div> BETA .1</div><div> &END<br>&END SCF<br></div><div><br></div><div><br></div><div>If you include your output it can also help us diagnose what is the problem and if there are improvements. </div><div><br></div><div>A side note to Augustine's suggestion. RI will not benefit ADMM. RI can be used to improve the speed of HFX with large basis, but since ADMM is a small basis the improvements go away.<br></div><div><br></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Thursday, December 22, 2022 at 4:34:02 AM UTC-8 DMT 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;">Hi Augustin,<div><br></div><div>Thank you for the conformation and advises. I will try RI</div><div><br></div><div>Best Regards,</div><div>Dobromir<br><br></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Thursday, December 22, 2022 at 1:30:57 PM UTC+2 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">
<div dir="ltr">
<div><span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)">Hi Dobromir,</span></div>
<div><span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)"><br>
</span></div>
<div><span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)">you should keep in mind that HFX is inherently an expensive method
(compared to GGA). From your input file, I would say you are already using all the tricks I know of:</span></div>
<div>
<div>
<ol>
<li style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;color:rgb(0,0,0);background-color:rgb(255,255,255)">
<span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)">Using the ADMM method</span></li><li style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;color:rgb(0,0,0);background-color:rgb(255,255,255)">
<span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)">Using a truncated Coulomb operator, although I have to warn you about using extreme values such
as 2.0 Angstrom (~6 is usually good)</span></li><li style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;color:rgb(0,0,0);background-color:rgb(255,255,255)">
<span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)">Using the largest possible value for MAX_MEMORY</span></li><li style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;color:rgb(0,0,0);background-color:rgb(255,255,255)">
<span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)">Using a loose EPS_SCHWARZ threshold. Here too, 1.0E-6, may be on the limit</span></li></ol>
<div><span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)">Also, I think that your EPS_DEFAULT value might be dangerously loose, if you want accurate
results. You could optionally try to use the RI-HFX method by adding the &RI subsection in &HF. Default parameters should be good enough. There is however no guarantee that it speeds up you particular calculation.</span></div>
<div><span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)"><br>
</span></div>
<div><span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)">Best,</span></div>
<div><span style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0);background-color:rgb(255,255,255)">Augustin<br>
</span></div>
</div>
<div><br>
</div>
</div>
<div><br>
</div>
<div></div>
<hr style="display:inline-block;width:98%">
<div dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> <a rel="nofollow">cp...@googlegroups.com</a> <<a rel="nofollow">cp...@googlegroups.com</a>> on behalf of DMT <<a rel="nofollow">dobro...@gmail.com</a>><br>
<b>Sent:</b> Thursday, December 22, 2022 12:02 PM<br>
<b>To:</b> cp2k <<a rel="nofollow">cp...@googlegroups.com</a>><br>
<b>Subject:</b> [CP2K:18243] Re: How to speed HF up</font>
<div> </div>
</div>
<div></div></div><div dir="ltr"><div>I tried
<div><br>
</div>
<div> !&PBE_HOLE_T_C_LR<br>
! CUTOFF_RADIUS 6.0<br>
! SCALE_X 0.25<br>
!&END PBE_HOLE_T_C_LR</div>
<div><br>
</div>
<div>in &XF_FUNCTIONAL and</div>
<div><br>
</div>
<div> &HF<br>
FRACTION 0.25<br>
&SCREENING<br>
EPS_SCHWARZ 1.0E-6 !DEFAULT 1.0E-10, TYPICAL -6 - -9, FOR STABLE HFX<br>
!SCREEN_ON_INITIAL_P T !FOR A GOOD INITIAL GUESS FROM A .WFN<br>
&END SCREENING<br>
&INTERACTION_POTENTIAL<br>
POTENTIAL_TYPE TRUNCATED !TRUNCATED 1/r (Coulomb) POTENTIAL FOR SPEED UP<br>
CUTOFF_RADIUS 6.0 !SHOULD BE < HALF THE CELL<br>
T_C_G_DATA /home/lsd/cp2k_data/t_c_g.dat !DATA FOR THE EVAL OF TRUNCATED GAMMA FUNC<br>
&END INTERACTION_POTENTIAL</div>
<div><br>
</div>
<div>in &XC and there is no significant (if any) speed up.</div>
<div><br>
</div>
<div>I even played with the CUTOFF_RADIUS (values from 2.0 to 6.0) and nothing changes.</div>
<div><br>
</div>
<div>Am I missing something ?</div>
<div><br>
</div>
<div>Best Regards,</div>
<div>Dobromir<br>
<br>
</div>
<div>
<div dir="auto">On Tuesday, December 20, 2022 at 8:31:44 PM UTC+2 DMT wrote:<br>
</div>
<blockquote style="margin:0 0 0 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
Hello,
<div><br>
</div>
<div>I have heard that there must be a way to speed HF (for hybrid DFT methods) up. Can you help me with that ?</div>
<div><br>
</div>
<div>Best Regards,</div>
<div>Dobromir</div>
</blockquote>
</div>
<p></p></div></div><div dir="ltr"><div>
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