[Wien] SDW calculation ?

[Gerhard Fecher]

Take care that you do not mix up spin density waves, spin-spirals (sometimes called "frozen phonons") and such things.
A good source to be read first is :
J. Kübler; "Theory of Itinerant Electron Magnetism";  Oxford Science Publications
and the original works on the matter that is cited there.

Also note that Cr is very special, I have the experience with Cr that the q-dependency of the spin spiral states
is very sensitive to all kinds of parameters, exchange-correlation functionals or whatever else one has to play arround.

Conclusion: Read youre Kübler very well, before he rejects the manuscript !


Ciao
Gerhard

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
________________________________________
Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.tuwien.ac.at]" im Auftrag von "Lyudmila V. Dobysheva [lyu at otf.pti.udm.ru]
Gesendet: Mittwoch, 16. Juni 2010 11:28
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] SDW calculation ?

Susanta Mohanta wrote
> > My question is regarding the spin structure for a SDW calculation.

The WIENNCM package that is developed by R Laskowski gives a possibility
to make an SDW using small unit cell with the help of generalised Bloch
theorem. Though, it would be interesting to compare the results from both
methods (large supercell with size equal to the SDW length with common
WIEN, and the small cell with the SDW of the same commensurate q-vector
with NCM).

> > the unit cell need to be extended in a particular
> > direction, equivalent or greater than the wave vector
efaan Cottenier wrote
> Generate a default case.inst, which will have initially these occupations:

By the way, from general considerations I am afraid that this method with
supercell for pure Cr will give bad convergency; namely, no convergency at
all. One would possibly need to fix the position of the node of the wave,
somehow. Otherwise, the iteration cycle may jump between equal solutions.

Martin Pieper wrote
>>> If the SDW is not a linear polarized wave but a helical one (I don't
>>> know for Cr) you will, to my knowledge, also be unable to model it
>>> exactly using the standard version of Wien2k, which only knows
>>> colinear spin structures.

WIENNCM makes helical, also.

Best wishes
Lyudmila Dobysheva
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