[CP2K-user] [CP2K:18251] Re: How to speed HF up

DMT dobromirak at gmail.com
Sat Dec 24 10:38:01 UTC 2022

Thank you for the suggestions.

Yes, when I try with a PBE GUESS the convergence is a lot faster. It starts 
with a lower Energy and improves by all factors much faster with the 

In my experience so far diagonalization is faster than OT. I usually try 

>From my testing Smearing does help with metal systems like graphene, but 
for organic molecules it only slows things down.

>From my testing Mixing can help with larger systems, but isn't Mixing only 
for periodic conditions and not supposed to be used with gas phase organics 


On Thursday, December 22, 2022 at 10:28:30 PM UTC+2 nwi... at berkeley.edu 

> 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.
> 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.
> 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.
> 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
> &SCF
>             MAX_SCF 100                    !DEFAULT 50
>             EPS_SCF 1.0E-5                !DEFAULT 1.0e-5, OT: -6 - -7, 
>             &DIAGONALIZATION T
>             &MIXING
>                     METHOD BROYDEN_MIXING
>                     ALPHA .01
>                     BETA .1
>              &END
> If you include your output it can also help us diagnose what is the 
> problem and if there are improvements. 
> 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.
> On Thursday, December 22, 2022 at 4:34:02 AM UTC-8 DMT wrote:
>> Hi Augustin,
>> Thank you for the conformation and advises. I will try RI
>> Best Regards,
>> Dobromir
>> On Thursday, December 22, 2022 at 1:30:57 PM UTC+2 Augustin Bussy wrote:
>>> Hi Dobromir,
>>> 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:
>>>    1. Using the ADMM  method
>>>    2. Using a truncated Coulomb operator, although I have to warn you 
>>>    about using extreme values such as 2.0 Angstrom (~6 is usually good)
>>>    3. Using the largest possible value for MAX_MEMORY
>>>    4. Using a loose EPS_SCHWARZ threshold. Here too, 1.0E-6, may be on 
>>>    the limit
>>> 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.
>>> Best,
>>> Augustin
>>> ------------------------------
>>> *From:* cp... at googlegroups.com <cp... at googlegroups.com> on behalf of 
>>> DMT <dobro... at gmail.com>
>>> *Sent:* Thursday, December 22, 2022 12:02 PM
>>> *To:* cp2k <cp... at googlegroups.com>
>>> *Subject:* [CP2K:18243] Re: How to speed HF up 
>>> I tried  
>>>                 !&PBE_HOLE_T_C_LR
>>>                 !    CUTOFF_RADIUS 6.0
>>>                 !    SCALE_X 0.25
>>>                 !&END PBE_HOLE_T_C_LR
>>> in &XF_FUNCTIONAL and
>>>             &HF
>>>                 FRACTION 0.25
>>>                 &SCREENING
>>>                     EPS_SCHWARZ 1.0E-6            !DEFAULT 1.0E-10, 
>>>                     !SCREEN_ON_INITIAL_P T         !FOR A GOOD INITIAL 
>>>                 &END SCREENING
>>>                 &INTERACTION_POTENTIAL
>>>                     POTENTIAL_TYPE TRUNCATED    !TRUNCATED 1/r (Coulomb) 
>>>                     CUTOFF_RADIUS 6.0            !SHOULD BE < HALF THE 
>>> CELL
>>>                     T_C_G_DATA /home/lsd/cp2k_data/t_c_g.dat     !DATA 
>>>                 &END INTERACTION_POTENTIAL
>>> in &XC and there is no significant (if any) speed up.
>>> I even played with the CUTOFF_RADIUS (values from 2.0 to 6.0) and 
>>> nothing changes.
>>> Am I missing something ?
>>> Best Regards,
>>> Dobromir
>>> On Tuesday, December 20, 2022 at 8:31:44 PM UTC+2 DMT wrote:
>>> Hello, 
>>> I have heard that there must be a way to speed HF (for hybrid DFT 
>>> methods) up. Can you help me with that ?
>>> Best Regards,
>>> Dobromir
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