Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Orbital order and magnetism of FeNCN   Based on density functional calculations, we report on the orbital order and
microscopic magnetic model of FeNCN, a prototype compound for orbital-only
models. Despite having a similar energy scale, the spin and orbital degrees of
freedom in FeNCN are only weakly coupled. The ground-state configuration
features the doubly occupied d_{3z^2-r^2} (a1g) orbital and four
singly-occupied d orbitals resulting in the spin S=2 on the Fe+2 atoms, whereas
alternative (Eg') configurations are about 75 meV/f.u. higher in energy.
Calculated exchange couplings and band gap are in good agreement with the
available experimental data. Experimental effects arising from possible orbital
excitations are discussed.

37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph