Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin-reversal energy barriers of 305 K for Fe$^{2+}$ $d^{6}$ ions with
  linear ligand coordination   A remarkably large magnetic anisotropy energy of 305 K is computed by quantum
chemistry methods for divalent Fe$^{2+}$ $d^6$ substitutes at Li-ion sites with
$D_{6h}$ point-group symmetry within the solid-state matrix of Li$_3$N. This is
similar to values calculated by the same approach and confirmed experimentally
for linearly coordinated monovalent Fe$^{1+}$ $d^7$ species, among the largest
so far in the research area of single-molecule magnets. Our ab initio results
therefore mark a new exciting exploration path in the search for superior
single-molecule magnets, rooted in the $d_{xy}^{1.5} d_{x^2-y^2}^{1.5}
d_{z^2}^1 d_{yz}^1 d_{zx}^1$ configuration of $d^6$ transition-metal ions with
linear or quasilinear nearest-neighbor coordination. This $d^6$ axial
anisotropy may be kept robust even for symmetries lower than $D_{6h}$, provided
the ligand and farther-neighbor environment is engineered such that the
$d_{xy}^{1.5} d_{x^2-y^2}^{1.5} d_{z^2}^1 d_{yz}^1 d_{zx}^1$ - $d_{xy}^{1}
d_{x^2-y^2}^{1} d_{z^2}^2 d_{yz}^1 d_{zx}^1$ splitting remains large enough.

19
The categories of this paper are: eess
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math