Calculating energy of bulk Fe using KPOINTS

[charles...@student.nmt.edu]

Hello,

I am trying to calculate properties of bulk Iron (BCC), and I'm trying to first determine the best number of K-Points to use. Starting with a small number (1 or 2) I am able to get a rather quick convergence in the simulation. However, once I use 3 or more, the simulation shows no convergence at all and does not finish. Has anyone calculated properties of a metallic system such as this using k-points in cp2k and experienced anything similar? 

Thank you!

Charles Griego 

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

Hi

just guessing: have you included additional states and an
appropriate smearing of the occupation?

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
---------------------------------------------------------------

-----cp...@googlegroups.com wrote: -----To: cp2k <cp...@googlegroups.com>
From: charles...@student.nmt.edu
Sent by: cp...@googlegroups.com
Date: 08/04/2016 02:50PM
Subject: [CP2K:8038] Calculating energy of bulk Fe using KPOINTS

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[Charles Griego]

Hi Juerg,

No, I do not think I specified parameters for smearing. Do you have any suggestions for specifying the appropriate smearing in the input file?

And by additional states, do you mean oxidation states and multiplicity?

Best

Charles Griego

On Fri, Aug 5, 2016 at 2:07 AM, <hut...@chem.uzh.ch> wrote:

Hi

just guessing: have you included additional states and an
appropriate smearing of the occupation?

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
---------------------------------------------------------------

-----cp...@googlegroups.com wrote: -----To: cp2k <cp...@googlegroups.com>
From: charles...@student.nmt.edu
Sent by: cp...@googlegroups.com
Date: 08/04/2016 02:50PM
Subject: [CP2K:8038] Calculating energy of bulk Fe using KPOINTS

Hello,
I am trying to calculate properties of bulk Iron (BCC), and I'm trying to first determine the best number of K-Points to use. Starting with a small number (1 or 2) I am able to get a rather quick convergence in the simulation. However, once I use 3 or more, the simulation shows no convergence at all and does not finish. Has anyone calculated properties of a metallic system such as this using k-points in cp2k and experienced anything similar? 
Thank you!
Charles Griego 



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

Hi

CP2K calculates by default only N/2 (number of electrons / 2, for spin restricted cases)
states. For metals you need additional state to hold partially filled states.
Check the literature for reasonable settings, here is an example (actual values might not
be appropriate for your example).

&SCF
SCF_GUESS ATOMIC
MAX_SCF 100
EPS_SCF 1.0e-6
&SMEAR
METHOD FERMI_DIRAC
ELECTRONIC_TEMPERATURE 500.
&END
&MIXING
METHOD DIRECT_P_MIXING
ALPHA 0.4
&END
ADDED_MOS 20 20
&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
---------------------------------------------------------------

-----cp...@googlegroups.com wrote: -----To: cp...@googlegroups.com
From: Charles Griego
Sent by: cp...@googlegroups.com
Date: 08/11/2016 04:48AM
Subject: Re: [CP2K:8049] Calculating energy of bulk Fe using KPOINTS

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