[Wien] Antiferromagnetic Calculation With Orbital Potentials

[David Tompsett]

Thank you Pavel and Stefaan for your help.

I have one more question about analysing the output from the found 
ground state.

I wish to know the effective moment for the ion. How do I combine the 
orbital moment (as projected along the chosen magnetization direction 
for SO coupling) and spin moments?

Thank you,
David.

Pavel Novak wrote:
> 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.
>>
>>
>>     
>
>   

-- 
David A. Tompsett
Quantum Matter Group
Cavendish Laboratory
J. J. Thomson Avenue
Cambridge CB3 0HE
U.K.
Tel: +44 7907 566351 (mobile)
Fax: +44 1223 768140
http://www-qm.phy.cam.ac.uk/