[Wien] Unit of :ORBxx

[Pavel Novak]

Dear colleagues,

here is the receipt to get desirable high orbital momentum:

1/ converge the LSDA calculation

2/ construct starting density matrix by hand, occupying fully all five
majority spin states (put 1 on the diagonal) and ML=2 minority spin state.
Leave remaining minority spin states empty.

3/ Run LDA+U +s-o calculation with reasonably large U (e.g. 0.7 Ry).

The starting configuration will survive the selfconsistent procedure so
that resulting orbital moment will be equal to 2.

Regards
Pavel Novak



_________________________________________________
Dr. Pavel Novak
Department of Magnetism and Superconductivity
Institute of Physics AS CR
Cukrovarnicka 10, 162 53 Praha 6, Czech Republic
tel: +420 2 20 318 532
e-mail: novakp at fzu.cz

On Tue, 5 Dec 2006, Stefaan Cottenier wrote:

>
> >I also think this is the case. As a little test, I try to calculate :ORB
> >of a free Fe atom by constructing a fcc Fe with a lattice constant of 8A
> >(3 times the real fcc Fe bulk). I turn on the orbital potential first, and then
> >add spin-orbit. Both OP and SO have their M's pointing in (0 0 1). Then
> >I get :ORB to be 0.2. How do I relate this number to the fact that a free Fe
> >atom has L=2? I thought I would have obtained :ORB very close to 2, though.
> >
> >
> I never did that particular test, but I would indeed expect something
> much closer to 2. Some hints:
>
> * Your lattice constant is a bit small. The FAQ recommends 30 bohr for
> free atom calculations ( http://www.wien2k.at/reg_user/faq/cohesive.html )
>
> * The orb package calculates properties only inside the muffin tin
> sphere. Try to take the largest Fe sphere that still makes sense (say
> 2.5 bohr), and see whether you get closer to the desired value.
>
> Stefaan
>
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