[Wien] Density Matrices with SO Coupling

[Pavel Novak]

Dear David,

answer to your question depends on whether your system is magnetic or 
nonmagnetic. In a nonmagnetic system SO does not lower the spatial 
symmetry and density matrix is related to site coordination system. In the 
presence of magnetization, z axis is along M, site coordination system is 
changed (with some rare exceptions) and density matrix is related to the 
new local coordination system.

Regards Pavel


 On Wed, 19 Aug 2009, David Tompsett wrote:

> Dear All,
> 
> I have a question about the definition of density matrices when used in
> combination with SO coupling.
> 
> Take an exampe where the density matrix is initialised for a 4f13 system with
> a hole in  Lz=3, Sz = -1/2 >. Then is the z-axis  of quantization defined with
> respect to the local rotation for that atom or with respect to the
> magnetization direction set in case.inso with respect to cartesian axes (for
> orthorhombic space group)?
> 
> Is the definition of the z-axis the same when SO interactions are NOT
> included?
> 
> This may be important regarding the effect of crystal fields.
> 
> Many thanks,
> David.
> 
> 

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