Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effects of trace elements on the crystal field parameters of Nd ions at
  the surface of Nd$_2$Fe$_{14}$B grains   Using first-principles calculations, we investigate the positional dependence
of trace elements such as O and Cu on the crystal field parameter $A_2^0$,
proportional to the anisotropy constant $K_u$ of Nd ions placed at the surface
of Nd$_2$Fe$_{14}$B grains. The results suggest the possibility that the
$A_2^0$ parameter of Nd ions at the (001) surface of Nd$_2$Fe$_{14}$B grains
exhibits a negative value when the O or Cu atom is located near the surface,
closer than its equilibrium position. At the (110) surface, however, O atoms
located at the equilibrium position provide a negative $A_2^0$, while for Cu
additions $A_2^0$ remains positive regardless of Cu's position. Thus, Cu atoms
are expected to maintain a positive local $K_u$ of surface Nd ions more
frequently than O atoms when they approach the grain surfaces in the Nd-Fe-B
grains.

35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con