Dear WIEN2k developers and users, I am trying to do a calculation on Na2IrO3, which has a band gap ~340meV and a zigzag antiferromagnetic order in its ground state, and I have some questions as follow:
1. To assign the zigzag antiferromagnetic order, what I did is that I first
made a cif file that has two inequivalent Ir atoms, and let WIEN2k decide
the symmetry for me. I adopted the generated structural file (attached in
this mail), checked the cif file in some visulization software and made
sure they were structurally equivalent except that there were 2
inequivalent Ir atoms instead of 1. Is this the proper way to generate
structural files for magnetically ordered systems?
2. After generating the desired structural file, I put up on Ir1 atom and
down on the other (Ir2), used several different combinations of U and J,
and I got the following results:
U(eV) J(eV) Ueff=U-J (eV) Moment(Ir1, Ir2)
Gap(meV)
2.1 0.6 1.5 0.22532,-0.22439
~700meV
2.4 0 2.4 0.30105,-0.30109
~750meV
3 0.6 2.4 0.23225,-0.23235
~900meV
3 1.5 1.5 0.17203,-0.17210
~900meV
First, in this test, it seems that the gap is affected by U only, not
Ueff=U-J. Second, the moments of Ir seemed to be closely related to J. In
this situation, what is the proper way to assign U and J? I am not sure how
much it means if I just try to tune U and J until they match the
experimental gap and/or theoretical moments.
3. I also have a question about the unit of moment given here; I understand
that the moments depend on the RMT sizes and I assumed the unit is in bohr
magneton, but the first value shown for Ir atom is 0.76697 and I am not
sure in what unit is this value and how it assigns the initial moment for a
certain element (say, Ir in my case). Also, the interstitial moments are
nearly 0 among all the cycles.
For this calculation, kpoints=450, RKmax=8 and I had to use the TEMP scheme
for it to converge. I appreciate any reply from you.
Yours sincerely,
Hung-Yu
Na2IrO3_order_PBE_kp450_TEMP.struct
Description: Binary data
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