Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The reconstruction of Rh(001) upon oxygen adsorption   We report on a first-principles study of the structure of O/Rh(001) at half a
monolayer of oxygen coverage, performed using density-functional theory. We
find that oxygen atoms sit at the center of the black squares of a chess-board,
$c(2\times 2)$, pattern. This structure is unstable against a rhomboid
distortion of the black squares, which shortens the distance between an O atom
and two of the four neighboring Rh atoms, while lengthening the distance with
respect to the other two. We actually find that the surface energy is further
lowered by allowing the O atom to get off the short diagonal of the rhombus so
formed. We predict that the latter distortion is associated with an
order-disorder transition, occurring below room temperature. The above rhomboid
distortion of the square lattice may be seen as a rotation of the empty, white,
squares. Our findings are at variance with recent claims based on STM images,
according to which it is instead the black squares which would rotate. We argue
that these images are indeed compatible with our predicted reconstruction
pattern.

15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph