Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum well states in two-dimensional gold clusters on MgO thin films   The electronic structure of ultra-small Au clusters on thin MgO/Ag(001) films
has been analyzed by scanning tunneling spectroscopy and density functional
theory. The clusters exhibit two-dimensional (2D) quantum well states, whose
shapes resemble the eigen-states of a 2D electron gas confined in a parabolic
potential. From the symmetries of the HOMO and LUMO of a particular cluster,
its electron filling and charge state is determined. In accordance to a DFT
Bader-charge analysis, aggregates containing up to twenty atoms accumulate one
to four extra electrons due to a charge transfer from the MgO/Ag interface. The
HOMO - LUMO gap is found to close for clusters containing between 70 and 100
atoms.

22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph