[CP2K-user] [CP2K:15464] some issues with ab initio MD with xTB

[am...@gmail.com]

Thanks so much prof. Hutter for your reply.
Attached, I provide an example. In the zip file there are two input scripts 
main_1.inp and main_2.inp which both run MD simulation with interactions 
evaluated by xTB for a simulation box containing 8 CO2 molecules. 
Everything is the same for the two scripts except the size of the 
simulation box which in main_2 is ca 2.5 times larger in each direction. 
For these two scripts, each MD step took on my system with 32 cores roughly 
0.64 and 11 s, respectively which seems kind of unusual to me.
I am wondering first of all, is it normal that for larger cells which 
contain exact same particles and default cut-off computations become so 
slower and are there some ways to avoid it, e.g. if someone need to study a 
very dilute gas state?
Thanks in advance and best regards,
Amin

On Thursday, May 27, 2021 at 4:46:35 PM UTC+2 jgh wrote:

> Hi
>
> without additional information you will not get any helpful replies.
>
> regards
>
> Juerg Hutter
> --------------------------------------------------------------
> Juerg Hutter Phone : ++41 44 635 4491 <+41%2044%20635%2044%2091>
> Institut für Chemie C FAX : ++41 44 635 6838 <+41%2044%20635%2068%2038>
> 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: "am... at gmail.com" 
> Sent by: c... at googlegroups.com
> Date: 05/26/2021 09:38AM
> Subject: [CP2K:15464] some issues with ab initio MD with xTB
>
>
> Hi everyone,
> I am trying to do some ab initio MD simulation with xTB to evaluate the 
> interatomic interactions.
> For a cubic cell with periodic boundary condition, for the same number of 
> particles, as I reduce the number density (for the same number of particles 
> only increasing the box size), the simulation time exponentially increases. 
> Does any one have any idea?
> Best regards,
> Amin
>
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