No subject

correct and calculated the total Energy in a field along z. The MAE now is
the difference between that value and the one calculated with the field
perpendicular z. So you do a second calculation with that field
orientation. 

And that's where things get tricky: you have to subtract two large numbers
(the total energies) to obtain a number which is especially in your case
VERY small. To see how small express the experimental MAE in Ry, the units
of :ENE in case.scf. You will see how many significant digits you will need
(and, probably, despair). Then be very carefull to converge your
calculations in energy better than that, and  that nothing but the field
direction changes between the two calculations. The catch here is that the
field will most probably lower symmetry and in a different way for the two
directions. From there on, the unit cell, the k-mesh ... change which might
very well change the result of the calculation by such a tiny energy. So
you should do the calculation in supercell where the symmetry is the same
for both field directions.

I hope this helps 

Martin


 

On Wed, 20 Apr 2011 22:13:27 +0400, Ирина Шихман
<shikhman.irina at gmail.com>
wrote:
> Dear Dr.Blaha and WIEN2K users,
> 
> I'm beginner user of Wien2k. For my scientific job I need to calculate
> Magnetocrystalline Anisotropy energy (MAE) of magnetite Fe3O4. I have
> read "User Guide" and "Orbital package in WIEN" (P.Novak, 2002), but I
> don't understand, how to do this calculations.
> 
> May be, I have to specify my actions step by step.
> 
> 1) After init.calc. I made case.inorb file with external field
> 
> 3 2 0
> BROYD 0.3
> 2 1 2
> 3 1 2
> 9.
> 0. 0. 1.
> 
> 
> 2) Then I ran single program called "orb"
> 
> 3) After that, I ran SCF calculations
> 
> I think, that result of this calculations is in the SCF files. So I
> analysed SCF-files and I saw that total Energy almost the same as one
> in my previous calculations without external field.
> 
> I'll be very pleased if anyone would tell me, what was wrong in my
actions.
> 
> Best regards,
> Irina
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> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien

-- 
Dr. Martin Pieper
Karl-Franzens University
Experimentalphysik
Universitätsplatz 5
A-8010 Graz
Austria
Tel. +43-1-58801-13132
+43-316-380-8564