[CP2K-user] [CP2K:10911] Re: cutoff convergence problems

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

Hi

my energy was with converged SCF, initial guess (SCF=1) is about 16.5 a.u.
The change in energy from 249->250 is about 0.005 a.u.
This is because of the discrete FFT grids. With 249 Ry you get a grid with 200 points,
with 250 Ry you get 216 points.

regards

Juerg
--------------------------------------------------------------
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
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-----cp... at googlegroups.com wrote: -----
To: "cp2k" <cp... at googlegroups.com>
From: hanno.... at kit.edu
Sent by: cp... at googlegroups.com
Date: 11/07/2018 02:06PM
Subject: [CP2K:10911] Re: cutoff convergence problems

  Hi Juerg,


  thanks for your answer. The reason why the number of SCF iterations was set to 1 is, that I generated this input to converge the cutoff and rel_cutoff of large systems (several hundrets of atoms, H2O is just a test system). This approach was described in the HOWTO on cp2k homepage https://www.cp2k.org/howto:converging_cutoff . The probleme with my input is the large energy jump when increasing the cutoff from 249 to 250 that appears with all systems I tested so far. To your energy value: did you increase the number of SCF cycles or change anything else?
   
  Again thank you for your help.
   
  Best,
  Hanno Schütz
   
  PhD student
   
  HIU-Helmholtz Institute Ulm  
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