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

[Xiaoming Wang]

Hi, Can you see it this time?

<https://lh3.googleusercontent.com/-f1GOmo2FRic/WcMpJhTURnI/AAAAAAAAGcU/MqO1xDMjsmQIV1PsgFDq5Aq_IqaPdz-CQCLcBGAs/s1600/benchmark.PNG>


On Wednesday, September 20, 2017 at 10:45:10 PM UTC-4, Matt W wrote:
>
> Hi,
>
> I only see the check for InCl3, not the main system?
>
> Matt
>
> On Thursday, September 21, 2017 at 10:36:15 AM UTC+8, Xiaoming Wang wrote:
>>
>> Hi Matt,
>>
>> Actually I also did the calculation for a supercell of 21*21*21 with 320 
>> atoms. PBE0 without TC are also tested, please see my benchmark tests in 
>> previous post (attachment in reply to Ling).
>>
>> Best,
>> Xiaoming
>>
>>
>> On Wednesday, September 20, 2017 at 10:27:48 PM UTC-4, Matt W wrote:
>>>
>>> That ADMM basis is already pretty large, so whilst it might be the 
>>> problem, first I'd check the cell size.
>>>
>>> Can you build a cell about 15 x 15 x 15 A or larger to allow you to 
>>> extend the range of the hybrid out to 6 or 7 A?
>>>
>>> You are truncating at about 5.25 A, which might not be enough to be 
>>> fully converged (note VASP won't be doing this as it works in K space). 
>>>
>>> Matt 
>>>
>>> On Thursday, September 21, 2017 at 8:36:29 AM UTC+8, Xiaoming Wang wrote:
>>>>
>>>> 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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