Broyden Mixing - K Points and Smear for Surface Energy Calculations

[Jonathan Kaufman]

Hi Everyone,

 I am using cp2k 5.1 and I am attempting to run surface energy calculations however I have run into a few issues. The first issue I am having is I am trying to use Broyden mixing and multiple k points. This causes an error "Method not implemented for k-points". Unfortunately it appears this is the case for every mixing method outside of Direct_P mixing. Is there a way to use Broyden mixing with multiple k points or can it only be run with a single gamma point? I attached the input file and output file for this run (the output is hafnia.SE.Broy.Kpoints.out).

Although this initial calculation was done on a single unit cell with full periodicity and will converge nicely (see output file hafnia.SE.Broy.out commented out smear and k points sections) I will want to run calculations with smearing because of surface interface. I do not understand why using an effective electronic temperature of 1 K cannot converge for a calculation that with absolutely no smearing converges very quickly. (see output file hafnia.SE.Broy.Smear.out).

Thank you,

Jonathan Kaufman

[James Dean]

Hi Jonathan,

With regards to your question on K-points, as far as I am aware K-points are still a little "misbehaved" in CP2K (they're a relatively new feature to the code, having only been introduced a couple of years ago). To the best of my knowledge, right now the most common practice is to use a single gamma-point and increase the number of repeated unit cells instead, until you get a good resolution in your reciprocal space.

Best,

James Dean

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

Hi

please use the MIXING section in SCF. This input works fine for me
with 4x4x4 kpoints.

&SCF
ADDED_MOS 32
SCF_GUESS ATOMIC
EPS_SCF 1.0E-8
MAX_SCF 100
&SMEAR ON
ELECTRONIC_TEMPERATURE 1000.0E+0 !Kelvin
METHOD FERMI_DIRAC
&END SMEAR
&MIXING
METHOD BROYDEN_MIXING
&END
&END SCF

regards

Juerg

--------------------------------------------------------------
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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To: "cp2k" <cp...@googlegroups.com>
From: "Jonathan Kaufman"
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Date: 08/15/2018 09:50PM
Subject: [CP2K:10630] Broyden Mixing - K Points and Smear for Surface Energy Calculations

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[attachment "attachments.inp.out.Broyden.zip" removed by Jürg Hutter/at/UZH]

[Jonathan Kaufman]

Juerg,

Thank you for your help. I was able to get the run to work as well.

Jonathan