[CP2K:7246] Warning when using HFX for a single molecule

[eft rsd]

Thanks a lot Juerg..  
ER 

On Wednesday, December 16, 2015 at 4:08:29 PM UTC, jgh wrote:
>
> Hi 
>
> - you can ignore the warning, even better if you explicitly switch 
>   off periodic images in the cell and Poisson sections. 
>
> - MOLOPT basis sets are very slow when used in HFX calculations 
>   (because of the very diffuse primitives). You van either 
>   switch to a more compact basis or use the ADMM approximation 
>   (see the ADMM paper by Guidon et al for more information). 
>
> regards 
>
> Juerg Hutter 
> -------------------------------------------------------------- 
> Juerg Hutter                         Phone : ++41 44 635 4491 
> Institut für Chemie C                FAX   : ++41 44 635 6838 
> Universität Zürich                   E-mail: hut... at chem.uzh.ch 
> <javascript:> 
> Winterthurerstrasse 190 
> CH-8057 Zürich, Switzerland 
> --------------------------------------------------------------- 
>
> -----cp... at googlegroups.com <javascript:> wrote: -----To: cp2k <
> cp... at googlegroups.com <javascript:>> 
> From: eft rsd 
> Sent by: cp... at googlegroups.com <javascript:> 
> Date: 12/16/2015 04:34PM 
> Subject: [CP2K:7246] Warning when using HFX for a single molecule 
>
> Dear CP2K folk, 
>
> I have two questions about employing the &HF flag for a relatively large 
> system. 
>
> My system consists of a single molecule made up by 70 atoms. I am using 
> the large basis of TZV2PX-MOLOPT-GTH-qx and the PBE0 functional with vdW 
> correction. This is how I wrote the functional flag 
>
> ###################################################### 
>     &XC 
>       &XC_FUNCTIONAL 
> &PBE 
> SCALE_X 0.75 
> SCALE_C 1.0 
> &END 
>       &END XC_FUNCTIONAL 
>       &XC_GRID 
>             XC_DERIV SPLINE2 
>       &END 
>       &VDW_POTENTIAL 
>         POTENTIAL_TYPE PAIR_POTENTIAL 
>         &PAIR_POTENTIAL 
>           TYPE DFTD3 
>           PARAMETER_FILE_NAME ./dftd3.dat 
>           REFERENCE_FUNCTIONAL PBE0 
>           D3_SCALING 1.0 1.287 0.928 *** 22:23:54 WARNING in 
> hfx_types:hfx_create_neighbor_cells :: Periodic   *** 
>  *** Hartree Fock calculation requested without use of a truncated or      
> *** 
>  *** shortrange potential. This may lead to unphysical total energies. Use 
> *** 
>  *** a truncated  potential to avoid possible problems. hfx_types.F line   
> *** 
>  *** 1411                                                                  
> *** 
>
>         &END PAIR_POTENTIAL 
>       &END VDW_POTENTIAL 
> &HF 
> FRACTION 0.25 
> &MEMORY 
> MAX_MEMORY 512 
> EPS_STORAGE_SCALING 1.0E-1 
> &END MEMORY 
> &SCREENING 
> EPS_SCHWARZ 1.0E-8 
> &END SCREENING 
> &END HF 
>     &END XC 
> ###################################################### 
>
>
> The questions are: 
> ) 
> 1- I tested the functional on a small system of 3 atoms and that was done 
> within hours. However, for the large system of 70 atoms the calculations 
> took ages (and were finally interrupted due to resource limits). The 
> questions is: Is this a normal calculation period for HF? Are there CP2K 
> options that I can use to speed up the calculations? 
>
> 2- When I checked what was printed out in the log file I found the 
> following message: 
>
>  *** 22:23:54 WARNING in hfx_types:hfx_create_neighbor_cells :: Periodic   
> *** 
>  *** Hartree Fock calculation requested without use of a truncated or      
> *** 
>  *** shortrange potential. This may lead to unphysical total energies. Use 
> *** 
>  *** a truncated  potential to avoid possible problems. hfx_types.F line   
> *** 
>  *** 1411                                                                  
> *** 
>
> Since this is a single molecule (in a very large box), can I safely ignore 
> the warning? 
>
>
> Thanks, 
> ER 
>
>
>
>
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