[CP2K-user] [CP2K:20164] Re: Hybrid functional issues

[xuan wang]

Thank you, Frederick,
In detail, for range-separated functional, I am allowed to use 
POTENTIAL_TYPE MIX_CL_TRUNC for wB7XD, CAM-B3LYP. The _TRUNC is truncated 
for HF exchange, and can be truncated by CUTOFF_RADIUS from our 
self-definition. But for HSE06, I can only use  POTENTIAL_TYPE SHORTRANGE 
rather than type with truncated condition, because I am acquired that the 
CUTOFF_RADIUS is defined by CP2K, not users, where this  CUTOFF_RADIUS is 
relevant with  EPS_DEFAULT,  omega=0.11,as you said. 

For range-separated functional, the coulomb operator can be seen as 1/r = 
[1-α-βerf(wr)]/r + [α+βerf(wr)]/r. In terms of wB7XD, α = 0.222036，β = 
0.777964，of CAM-B3LYP, α = 0.19，β = 0.46. While in principle, HSE06 can 
also be seen α = 0.25，β = -0.25, that we can use  POTENTIAL_TYPE 
MIX_CL_TRUNC. But not the condition, only recommeded to use POTENTIAL_TYPE 
SHORTRANGE. 

I don't know why. I am dying for understanding why. 

在2024年5月3日星期五 UTC+8 20:13:30<Frederick Stein> 写道：

> Dear Garrett,
> If I understand your question correctly, this affects all range-separated 
> hybrid functionals, i.e. all functionals with an explicit short/long-range 
> Coulomb or Gaussian potential contribution. This warning is relevant if you 
> as a user have to choose some parameters of the functional on your own. If 
> all parameters of the functionals (CUTOFF_RADIUS, OMEGA) are pre-defined by 
> the functional like in HSE06, you may ignore this warning. In the case of 
> HSE06 with omega=0.11, you will probably not be able to get rid of this 
> warning in real-case scenarios because with usual values of EPS_DEFAULT of 
> at most 1.0E-10, this cutoff radius is at least at the order of 20 A.
> HTH,
> Frederick
>
> xuan wang schrieb am Freitag, 3. Mai 2024 um 13:50:03 UTC+2:
>
>> Dear all,
>>
>> I learned that in CP2K, the use of HSE06 for periodic calculations is not 
>> allowed to use POTENTIAL_TYPE TRUNCATED, but POTENTIAL_TYPE SHORTANGE. 
>> However, even SHORTANGE will also assume a cutoff_radius which is not 
>> defined by users. 
>>
>> I am wondering about how many functionals behave like such HSE06? 
>>
>>
>> Thank you! 
>>
>> Best regards,
>> Garrett
>>
>

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