[CP2K-user] GEO_OPT a molecular is 10000 time longer then gaussian

Vladimir Rybkin rybk... at gmail.com
Fri May 15 11:41:12 UTC 2020

Dear Linfeng,

a few general remarks:
1) CP2K is not the most efficient tool for small molecules. For instance, 
it does a lot of integrations over cells in real and reciprocal space, and 
for a small molecule the cell is almost everywhere empty.
2) CP2K does not use internal coordinates for optimisation. This has to do 
with the fact that it's mostly meant for large periodic systems. Gaussians' 
Berny algorithm does use internal coordinates and is very efficient for 
small systems.
3) It's very likely that you 150 steps have not change the geometry 
4) It's not completely clear where this 10000 times come from. It may have 
to do with how you compile and run your applications.

That said, there's no specific problems with optimisers and efficiency. 
It's about applicability of tools for specific purposes. If you going to 
work with small molecules, you'd better stick to programs made for them, 
i.e. Gaussian. CP2K is meant for large and/or periodic systems.



пятница, 15 мая 2020 г., 2:51:51 UTC+2 пользователь Linfeng Gan написал:
> Hi all,
> When I optimized 1-butene molecular at B3lYP/6-311G** level, it took much 
> much longer than gaussian16 did.  I had test optimizer CG, BDGS and 
> LBFGD, nothing better. It seems the optimizers have some efficiency issues. 
> All three optimizer had taken at least 150 optimization steps to get the 
> final structure, but the initial structure had been optimized by gaussian. 
>   How could I improve that?
> Best
> Linfeng
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