[CP2K-user] [CP2K:13147] Re: R_CUTOFF vdWaals pair potential

[Austin clark]

Thanks Juerg,

I am running NPT simulations on molten salts. Is there a way to set the 
cutoff to always be 1/2 of the box length? Also what are the dangers of 
longer Coulombic cutoffs is in a system of monatomic ions?

On Wednesday, April 22, 2020 at 4:05:31 AM UTC-6, jgh wrote:
>
> Hi 
>
> for long range Coulomb interactions in SE you should use the 
> Ewald method. The Coulomb Cutoffs are then only for the 
> short range atomic type dependent part. The short range part is 
> minimum image. 
>
> regards 
>
> Juerg Hutter 
> -------------------------------------------------------------- 
> Juerg Hutter                         Phone : ++41 44 635 4491 
> Institut für Chemie C                FAX   : ++41 44 635 6838 
> Universität Zürich                   E-mail: h... at chem.uzh.ch 
> <javascript:> 
> Winterthurerstrasse 190 
> CH-8057 Zürich, Switzerland 
> --------------------------------------------------------------- 
>
> -----c... at googlegroups.com <javascript:> wrote: ----- 
> To: "cp2k" <c... at googlegroups.com <javascript:>> 
> From: "Austin clark" 
> Sent by: c... at googlegroups.com <javascript:> 
> Date: 04/21/2020 06:33PM 
> Subject: Re: [CP2K:13147] Re: R_CUTOFF vdWaals pair potential 
>
> Hi all, 
>
> I see that some SE codes do use the minimum image convention. Is the 
> coulombic cutoff one of these, or can the cutoff be larger than one half of 
> the cell length? 
>
> Thanks, 
> Austin 
>
>
>
> On Monday, May 23, 2016 at 6:19:29 AM UTC-6, Guilherme da Silva wrote: 
> Hi, 
>
> Thanks for answering so fast! 
>
> regards, 
>
> Guilherme 
>
> Em segunda-feira, 23 de maio de 2016 08:51:04 UTC-3, jgh  escreveu:Hi 
>   
> In almost all parts of the program (exceptions are some DFTB and SE codes, 
> and maybe HFX) CP2K does not use the minimum image convention. It is save 
> to use 
> interaction ranges that are larger than the simulation box. 
>   
> regards 
>   
> Juerg 
> -------------------------------------------------------------- 
> Juerg Hutter                         Phone : ++41 44 635 4491 
> Institut für Chemie C                FAX   : ++41 44 635 6838 
> Universität Zürich                   E-mail: h... at chem.uzh.ch 
> Winterthurerstrasse 190 
> CH-8057 Zürich, Switzerland 
> --------------------------------------------------------------- 
>   
> -----c... at googlegroups.com wrote: -----To: cp2k <c... at googlegroups.com> 
> From: Guilherme da Silva   
> Sent by: c... at googlegroups.com 
> Date: 05/23/2016 01:42PM 
> Cc: j... at science.ru.nl 
> Subject: [CP2K:7782] Re: R_CUTOFF vdWaals pair potential 
>   
> Hi, 
> I know that this one is a bit too old, but I have a similar doubt. 
>   
> I think he argues about the possibility of high r_cutoff values to violate 
> the minimum-image convention. Is that simply not true? 
>   
> And if it does violate, have anyone some answer about what would be worse: 
> to violate the mic or to not compute the dispersion correction in an 
> appropriate range? 
>   
> Regards, 
>   
> Em terça-feira, 17 de dezembro de 2013 09:35:30 UTC-2, JanLos  escreveu: 
>     
>   
>       
>     
>     
>     Dear CP2K developpers, 
>   
>     I  was wondering about the comment in the section   
>   
>     "FORCE_EVAL/DFT/XC/VDW_POTENTIAL/PAIR_POTENTIAL/R_CUTOFF", 
>   
>     saying "The cutoff will be 2 times this value".   
>   
>     If I stick to the default value of 10.06 Angstrom for this 
>     parameter,   
>   
>     the cut-off will be 20.12 Angstrom, which is pretty large, but OK.   
>   
>     If this is really what is applied, then it would imply that for a 
>     cubic simulation   
>   
>     box of 20 A cube with periodic boundary conditions, R_CUTOFF should 
>     not   
>   
>     be set larger than 5.0 Angstrom in order to NOT exceed recommended   
>   
>     maximal value for this box size, namely half the box size. Do I see 
>     this correctly ? 
>   
>     It's just that the comment " The cutoff will be 2 times this 
>       value" confuses me,   
>   
>     asking myself why this input parameter been defined in this way. 
>   
>     By the way, is the minimal image convention applied for the 
>     calculation 
>   
>     of these interactions ? 
>   
>                                                                     
>     Regards,                  Jan Los 
>   
>       
>   
>     
>   
>   
>   
>   
>   
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