[Wien] RKMAX and k-mesh

[Jorissen Kevin]

Hello,
 
total energies may be difficult to converge.
If you look eg. at DOS or energy differences between two calculations, you will probably see it's converged at a much lower rkmax.
 
In fact, sometimes you aren't able to converge the total energy at all.
 
 
Kevin Jorissen
 
EMAT - Electron Microscopy for Materials Science   (http://webhost.ua.ac.be/emat/)
Dept. of Physics
 
UA - Universiteit Antwerpen
Groenenborgerlaan 171
B-2020 Antwerpen
Belgium
 
tel  +32 3 2653249
fax + 32 3 2653257
e-mail kevin.jorissen at ua.ac.be
 

________________________________

Van: wien-admin at zeus.theochem.tuwien.ac.at namens Sergio L. Palacios Diaz
Verzonden: di 22-2-2005 16:26
Aan: wien at zeus.theochem.tuwien.ac.at
Onderwerp: [Wien] RKMAX and k-mesh



Hello Wien community !

Just a simple question (I think):

I am running Wien2k for fcc-Ni and performing an analysis similar to
that done by S. Cottenier for bcc-Fe in his tutorial about LAPW methods.
The values of the total energy are decreasing for increasing values of
the RKMAX parameter and from RKMAX=11 the total energy starts to
increase. So, the optimal value (after S. Cottenier) is RKMAX=10.5
approx.
The k-mesh employed consists of 5000 k-points (165 in the irreducible
part).
I am wondering the following questions:
Is there something wrong in using such an unusual RKMAX value (the
recommended values are from 5 to 9)?
Is the effect of decreasing RKMAX similar to that of increasing the
k-mesh?

Any hint will be welcome.

Regards,
--
Dr. Sergio L. Palacios
Profesor Titular de Física Aplicada
Dpto. de Física--Facultad de Ciencias
Universidad de Oviedo
C/ Calvo Sotelo s/n
Oviedo 33007
Spain
Phone: +34 98 5 10 28 48
Fax: +34 98 5 10 33 24
e-mail: sergio at pinon.ccu.uniovi.es; slpalacios at uniovi.es

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