[CP2K-user] [CP2K:18245] Re: How to speed HF up

[DMT]

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, 
> TYPICAL -6 - -9, FOR STABLE HFX
>                     !SCREEN_ON_INITIAL_P T         !FOR A GOOD INITIAL 
> GUESS FROM A .WFN
>                 &END SCREENING
>                 &INTERACTION_POTENTIAL
>                     POTENTIAL_TYPE TRUNCATED    !TRUNCATED 1/r (Coulomb) 
> POTENTIAL FOR SPEED UP
>                     CUTOFF_RADIUS 6.0            !SHOULD BE < HALF THE CELL
>                     T_C_G_DATA /home/lsd/cp2k_data/t_c_g.dat     !DATA FOR 
> THE EVAL OF TRUNCATED GAMMA FUNC
>                 &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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