CDFT ADJUST_SIZE

[Nico Holmberg]

Hi,

This keyword is explained in detail in the tutorial you linked, see in 
particular Figure 2. In brief, the ADJUST_SIZE keyword determines whether 
the size of atoms, as defined by atom type specific radii (keyword 
ATOMIC_RADII), should be accounted for in the construction of the CDFT 
constraints. The default FALSE value indicates that all atoms are treated 
equally (i.e. they have the same atomic radius). This can lead to strange 
partial charges as discussed in the tutorial. If you set the keyword to 
TRUE, you can choose different atoms to have different sizes which leads to 
physically reasonable partial charges. You should run the water dimer part 
<https://www.cp2k.org/howto:cdft#selected_examples> of the tutorial to get 
a better understanding on how this scheme affects the calculated partial 
charges. 

BR,

Nico




tiistai 5. kesäkuuta 2018 12.32.28 UTC+3 Anton S. Lytvynenko kirjoitti:
>
> Dear colleagues,
>
> I try to apply CDFT tutorial to my systems and wonder about the meaning of 
> ADJUST_SIZE variable.
>
> In the reference manual:
> "ADJUST_SIZE {Logical}
> Adjust Becke cell boundaries with atomic radii to generate a heteronuclear 
> cutoff profile. These radii are defined with the keyword ATOMIC_RADII.
> This keyword cannot be repeated and it expects precisely one logical.
> The lone keyword behaves as a switch to .TRUE.
> Default value: .FALSE."
>
> However, the CDFT tutorial ( https://www.cp2k.org/howto:cdft ) explicitly 
> sets ADJUST_SIZE to FALSE.
>
> How the program will behave if ADJUST_SIZE is set to FALSE and to TRUE? 
> What is the difference?
>
> Thanks in advance.
>
> Yours sincerely,
> Anton Lytvynenko.
>
>
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