[CP2K-user] Slow calculating speed of HSE06

[ma...@gmail.com]

Hi Matt and Nick,

Thanks for your help! These information are very useful.

Regards,
Hongyang

在2021年4月10日星期六 UTC+10 上午4:16:05<Matt W> 写道：

> Yeah. This is correct. You need the interaction to basically decay by half 
> the cell length or weirdness might occur.
>
> On Friday, April 9, 2021 at 6:32:53 PM UTC+1 n... at berkeley.edu wrote:
>
>> Another thing I suspect is tripping up this small system is the HFX 
>> implementation in CP2K. The way CP2K calculates HFX means that periodicity 
>> isn't handled nicely (maybe Matt can comment on why this is?) and so the HF 
>> interaction potential needs to decay before it reaches periodic images, 
>> this is why most people who are doing CP2K will use a truncated PBE0 with 
>> the truncation radius of 1/2 the minimum cell dimension. For HSE06, the the 
>> effective interaction distance is 1 / screening = 1 / .2 = 5 Angstroms. So 
>> for a primitive cell like you have, you're actually probably unphysically 
>> including HF effects across the periodic boundary, which could be what's 
>> making the calculation take so long. Just further reason to use cp2k for 
>> larger cells.
>>
>> On Friday, April 9, 2021 at 6:09:07 AM UTC-7 Matt W wrote:
>>
>>> I hadn't seen the earlier messages in another thread. At a quick glance 
>>> your input looks fine. I'd decrease EPS_DEFAULT to 10^-14 or something to 
>>> be sure things were set up accurately. Make sure you restart from a GGA 
>>> converged solution.
>>>
>>> It will, of course, get more expensive for bigger cells but in the limit 
>>> of really big cells only linearly with sytem size. 
>>>
>>> CELL_OPT can be quite expensive with hybrids. You could just do a volume 
>>> sweep with static calcs as you have a cubic cell.
>>>
>>> Matt
>>> On Friday, April 9, 2021 at 1:31:02 PM UTC+1 ma... at gmail.com wrote:
>>>
>>>> Dear Matt,
>>>>
>>>> Yes, I know GAMMA point for such a small system doesn't make sense. I 
>>>> did this calculation just for exercise because I thought small system will 
>>>> save time. I thought a small system already took such a long time, the 
>>>> larger system would take much longer. But based on your description, it 
>>>> seems what I though is totally wrong. I would run some large supercell 
>>>> systems later. Thanks!
>>>> By the way, regarding the attached input file that I used, could you 
>>>> please have a look when you are free and provide some suggestions that may 
>>>> improve the performance (e.g., speed and stability) based on your expertise?
>>>>
>>>> Thanks & Regards,
>>>> Hongyang
>>>>
>>>> 在2021年4月9日星期五 UTC+10 下午10:12:47<Matt W> 写道：
>>>>
>>>>> You can't run an 8 atom system without k-points, it doesn't make sense 
>>>>> and you can't run hybrid functionals with k-points at the moment.
>>>>>
>>>>> Absolute minimum is a 64 atom system (still nowhere near converged). 
>>>>> For the HSE screened exchange, I'd suggest you wil need box dimensions of 
>>>>> _at least_ 1 nm on each side otherwise strange things will happen. 
>>>>>
>>>>> If ADMM is working well the extra cost of going to bigger systems will 
>>>>> not be too big. Plane wave code will be more efficient for the smallest 
>>>>> cells, but CP2K should win out for bigger defect cells.
>>>>>
>>>>> Matt
>>>>>
>>>>> On Friday, April 9, 2021 at 9:47:52 AM UTC+1 ma... at gmail.com wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I'm a beginner of using cp2k7.1. My aim is to use HSE06 to calculate 
>>>>>> the Si (8 atoms) system. However the calculating speed is extremly slow. I 
>>>>>> used OT and ADMM approaches and GAMMA point with 48 cores, but this 
>>>>>> CELL_OPT calculation took around 30 mins to finish. As a comparison, I used 
>>>>>> VASP to run the same geometry with HSE06 and with only 1 core, the 
>>>>>> calculation finished in 50 seconds... So clearly, I must did something 
>>>>>> wrong in the input file resulting in a significant limitation in the 
>>>>>> calculating speed but I couldn't figure out which part is wrong. Could 
>>>>>> somebody please provide some help? Thanks.
>>>>>>
>>>>>> Regards,
>>>>>> Hongyang
>>>>>>
>>>>>
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