Magmom settings with oxygen atoms on graphite

Queries about input and output files, running specific calculations, etc.


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lahaye
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Magmom settings with oxygen atoms on graphite

#1 Post by lahaye » Tue Oct 24, 2006 11:47 am

Hi,

I have Oxygen (and also OH) on a graphite sheet (graphene).
With the Oxygens, I suppose I should do a spin-polalized calculation.

From the guidebook I learned that I first should do calculations
without spin-polarization: relax and accurate total energy.

From that last result, I keep the CHGCAR and WAVECAR files
and calculate accurate total energy with ISPIN=2 and ICHARG=1.
From the Handson lectures (from VASP webpage),
I learned that I also should set reasonable values for MAGMOM.

My main question is, how to set reasonable values for MAGMOM in
this graphite - Oxygen - OH system. Say, I have in my supercell
8 C-atoms, 2 Oxygen and 1 Hydrogen, would this then be a good
start:
MAGMOM = 8*0 2*2 1*0
assuming that the Carbons and the Hydrogen will not contribute to the
magnetic moment, but the Oxygens will with a magnetic moment of 2
each. Is that a reasonable assumption? Or would this be better:
MAGMOM = 8*2 2*2 1*1


My POTCAR file has "LEXCH = PE"; should I then NOT use VOSKOWN,
as that is only desirable with PW91 functionals ???

Thank you,
Rob.
Last edited by lahaye on Tue Oct 24, 2006 11:47 am, edited 1 time in total.

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Magmom settings with oxygen atoms on graphite

#2 Post by admin » Tue Oct 24, 2006 1:40 pm

if you assume that any atom will not have a significant spin-polarization, you can safely start by setting MAGMOM=0 for that atom. The self-consistency procedure will then stabilize the scf solution of the local moments as well.

VOSKOWN only has to be set for PW91.
Last edited by admin on Tue Oct 24, 2006 1:40 pm, edited 1 time in total.

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