[Wien] AFM calculations

[Jian-Xin Zhu]

Dear Wien2k users and Prof. Blaha,

I am doing a AFM calculation with s.o. in USb2.
Several questions for your help:

1. The nonmagnetic USb2 has the tetragonal layered structure with P4/nmm
symmetry.

The cell has 6 atoms with lattice constant a, b=a, and c.  In the AFM
state, the magnetic cell is doubled with respect to the chemical cell.
Specifically, the lattice constant along the c direction is doubled.

When I prepare the USb2.struct_supergroup file of the nonmagnetic state,
should I keep the lattice parameters as the original (i.e., a, b=a, c), or
take  them to match the magnetic cell (i.e., a, b=a, 2c)?

If I follow the first way, x afminput does not create the input file for
the program CLMCOPY. If I follow the second way by specifying the symmetry
type as P in w2web,
after running sgroup, it came with a warning of reducing the lattice
constant from 2c to c, essentially going back to the first way.

If I insisted to use the primitive type P and specify 12
inequivalent atoms in the cell, the complaints with "incorrect symmetry"
came out.

So what's the correct way to construct USb2.struct_supergroup?

2. I assume the magnetism comes from the 5f state on U by flipping the
corresponding occupation on U in the file of USb2.inst.

U
Rn 3
5, 3,0.0  N      <----
5, 3,3.0  N      <----
6, 2,1.0  N
6, 2,0.0  N
7,-1,1.0  N
7,-1,1.0  N
U
Rn 3
5, 3,3.0  N      <----
5, 3,0.0  N      <----
6, 2,1.0  N
6, 2,0.0  N
7,-1,1.0  N
7,-1,1.0  N
U
Rn 3
5, 3,3.0  N      <----
5, 3,0.0  N      <----
6, 2,1.0  N
6, 2,0.0  N
7,-1,1.0  N
7,-1,1.0  N
U
Rn 3
5, 3,0.0  N     <----
5, 3,3.0  N     <----
6, 2,1.0  N
6, 2,0.0  N
7,-1,1.0  N
7,-1,1.0  N


However, the UG also reminds that we should set a zero moment (identical
spin up and spin down occupations) for all "non-magnetic" atoms.
In my case, the non-magnetic atoms are Sb. However, there is
one spin up  electron on n=5,kappa=1,
no spin down electron on n=5, kappa=1,
two spin up electrons on n=5, kappa=-2,
no spin down electron on n=5, kappa=-2,
as shown below.

I can split 2 electron on n=5 and kappa=-2 into one with spin up and the
other with spin dn.
Then what should do with the only one electron on n=5 and kappa=1? Can I
put it as
0.5 and 0.5? I don't find a discussion on this situation.

Sb
Kr 5
4, 2,2.0  N
4, 2,2.0  N
4,-3,3.0  N
4,-3,3.0  N
5,-1,1.0  N
5,-1,1.0  N
5, 1,1.0  N
5, 1,0.0  N
5,-2,2.0  N
5,-2,0.0  N

============>

Sb
Kr 5
4, 2,2.0  N
4, 2,2.0  N
4,-3,3.0  N
4,-3,3.0  N
5,-1,1.0  N
5,-1,1.0  N
5, 1,0.5  N      <----?
5, 1,0.5  N      <----?
5,-2,1.0  N    <----
5,-2,1.0  N    <----


Thanks you in advance for help.

Jian-Xin Zhu