[CP2K-user] [CP2K:12815] SCAN convergence problems for charged systems

[hut... at chem.uzh.ch]

Hi

I couldn't find a clear bug for this. My current best guess is
that the problem is related to the numerical instabilities
of the SCAN functional. 
Molecules in large boxes have many grid points with small and 
'random' density/gradient values that cause problems.
Your special case works for me in a 8x8x8 box (instead of 10x10x10)!

regards

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

-----cp... at googlegroups.com wrote: -----
To: "cp2k" <cp... at googlegroups.com>
From: "Chris Ahart" 
Sent by: cp... at googlegroups.com
Date: 01/24/2020 04:45PM
Subject: [CP2K:12815] SCAN convergence problems for charged systems

Dear CP2K users,

I am attempting to use the SCAN functional from libXC 4.2.1 with CP2K 6, performing some basic benchmark calculations from the G12IP dataset. While SCAN converges well for neutrals systems, I am unable to get convergence for a charged system.

I attach an example of the CH4 system (input and output for both neutral and charged), where the neutral state converges within 20 steps while the charged state immediately diverges. I have observed the same behaviour with many other systems. I have also tried using LDA pseudopotentials as well as the SCAN optimised pseudopotentials from github.com/juerghutter/GTH, in addition to all electron calculations. I have confirmed that the same input file converges with HF, and with PBE from both the CP2K implementation and from libXC.

I have also found that the charged system converges when only the correlation part of the SCAN functional is included, suggesting that the problem may be related to the exchange part of the SCAN functional.

Any help with this problem would be greatly appreciated.

Regards,
Chris  
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[attachment "charged.inp" removed by Jürg Hutter/at/UZH]
[attachment "charged.out" removed by Jürg Hutter/at/UZH]
[attachment "neutral.inp" removed by Jürg Hutter/at/UZH]
[attachment "neutral.out" removed by Jürg Hutter/at/UZH]