The calculation speed of SCAN

[zhouk...@gmail.com]

Dear all,

Now I am calculation bulk water using SCAN (BOMD). According to the literature, the energy cutoff of SCAN is 1200 Ry, which is much higher than PBE+D3 (500 Ry).

My system is 64 water molecules in a cubic box. 

Using 24 CPUs, the speed of SCAN is ~ 50 s/step that is much slower than PBE+D3 (~ 9 s/step). I have experience on SCAN using VASP that won’t cost much more time than PBE.

Can anyone share the experience on SCAN, especially for the calculation speed and acceleration of calculation?

The attachment is my input file.

Best,

Ke

[hut...@chem.uzh.ch]

Hi

without seeing the timings I will have to guess:
the increase is coming from more time needed for
1) libxc
2) FFT
3) collocate/integrate

you can try to set NGRIDS in
CP2K_INPUT / FORCE_EVAL / DFT / MGRID
to a higher value (e.g. 6). That should help with 3)

Another solution might be to work with GAPW and a lower cutoff,
but that needs testing.

regards

Juerg Hutter
--------------------------------------------------------------
Juerg Hutter Phone : ++41 44 635 4491
Institut für Chemie C FAX : ++41 44 635 6838
Universität Zürich E-mail: hut...@chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

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Date: 04/01/2021 04:59AM
Subject: [CP2K:15056] The calculation speed of SCAN

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[attachment "water.inp" removed by Jürg Hutter/at/UZH]

[zhouk...@gmail.com]

Dear Prof. Juerg Hutter,

Thank you very much for your suggestions.

Let me test.

Best,

Ke 

[zhouk...@gmail.com]

It works when I change NGRIDS from 4 to 6 and the cost will reduce ~15%.

Best,

Ke