[CP2K:9450] Re: Hybrid functional calculation results show large difference with VASP

[Xiaoming Wang]

Hi Ling,

Thanks for your comments. I have attached my benchmark results here.  Based 
on my tests, it seems that the ADMM basis set size is not so important for 
ionic crystals. One can get reasonable results even with smallest basis 
sets. Btw, the cutoff and rel_cutoff used are well converged values for my 
target property. So I think there is still room to improve the ADMM basis 
for Ag and In (with semicore d states in the valence). To check whether it 
is the problem of Ag and In ADMM basis, the simplest way is to do the PBE0 
calculations without ADMM. But the calculation takes me too long time, as 
also pointed out by Juerg. I suspect if it is possible to do HFX without 
ADMM using MOLOPT basis sets.





Best,
Xiaoming

On Wednesday, September 20, 2017 at 6:20:09 AM UTC-4, S Ling wrote:
>
> Hi
>
> I am not sure whether you are using the same ADMM basis sets (see your 
> initial input) for these new test calculations. One thing which I can see 
> is that you are not using the largest available ADMM basis sets for some of 
> the elements, e.g. the largest available ADMM basis sets for Cl, Ag and In 
> are pFIT3, FIT12 and FIT13, respectively. Taking In as an example, the 
> FIT13 ADMM basis set of In contains more p and d functions than FIT11, 
> which may be important for your system. 
>
> You mentioned a few different functionals, including PBE, PBE0 and HSE06, 
> and you have run quite a lot of benchmark tests. It would help if you can 
> tabulate all the numbers you have got (including the reference), so we can 
> understand your problem better.
>
> In addition, I can see you're using a CUTOFF of 250 Ry. Please also check 
> whether your calculation is converged with respect to this parameter.
>
> Please also keep in mind that CP2K and VASP use different pseudopotentials 
> and basis sets. I wouldn't expect the two codes to give the same numbers 
> for your target properties. If you look into literatures, you will also 
> find people reporting different numbers for the same property using the 
> same method and code.
>
> SL
>  
>
>
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