[Wien] Antiferromagnetic Calculation With Orbital Potentials

[Pavel Novak]

Dear David,

I believe that two solutions you obtained just reflect the fact that with 
very localized 4f states multiple solutions may be obtained, especially 
when applying the orbital potentials. Criterion for the ground state is 
the lowest total energy. 

Regards
Pavel 

On Tue, 12 May 2009, David Tompsett wrote:

> Dear All,
>              I am studying the magnetic ground state of a metallic 
> system. The magnetic atoms are Yb, and I am localizing the 4f moment 
> using an orbital potential, as well as applying spin-orbit coupling.
> 
> I have a question about the behaviour of the spin moments depending on 
> my input to case.inst
> Firstly, I set the starting spins such that the 5d electron and 4f hole 
> have a net spin and are flipped between the two Yb atoms:
> Yb
> Xe 4 
> 4, 3,3.0  N
> 4, 3,3.0  N
> 4,-4,4.0  N
> 4,-4,3.0  N
> 5, 2,1.0  N
> 5, 2,0.0  N
> 6,-1,1.0  N
> 6,-1,1.0  N
> 
> Yb2
> Xe 4 
> 4, 3,3.0  N
> 4, 3,3.0  N
> 4,-4,3.0  N
> 4,-4,4.0  N
> 5, 2,0.0  N
> 5, 2,1.0  N
> 6,-1,1.0  N
> 6,-1,1.0  N
> In this case the moments between the two Yb atoms go towards spin 
> moments of +2u and -1u during the convergence. Not an antiferromagnetic 
> solution.
> 
> Second, I set the 6s spin to 0.5 up and 0.5 down( ie. not net spin) in 
> case.inst:
> Yb
> Xe 4 
> 4, 3,3.0  N
> 4, 3,3.0  N
> 4,-4,4.0  N
> 4,-4,3.0  N
> 5, 2,0.5  N
> 5, 2,0.5  N
> 6,-1,1.0  N
> 6,-1,1.0  N
> 
> Yb2
> Xe 4 
> 4, 3,3.0  N
> 4, 3,3.0  N
> 4,-4,3.0  N
> 4,-4,4.0  N
> 5, 2,0.5  N
> 5, 2,0.5  N
> 6,-1,1.0  N
> 6,-1,1.0  N
> Then, a stable antiferromagnetic solution was found.
> 
> Questions:
> 1) Does the different behaviour occur because I am only applying my 
> orbital potential to the 4f states and not 5d?
> 
> 2) Is there some other physics to explain this? Is there something that 
> I can check to diagnose the behaviour in the first case?
> 
> Thanks,
> David.
> 
> 

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