Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theoretical Study of Small (NaI)n Clusters   A systematic theoretical study of stoichiometric clusters (NaI)n up to n=15
is performed using the ab initio Perturbed-Ion (PI) model. The structures
obtained are compared to previous pair potential results, and observed
differences between (NaI)n clusters and previous ab initio results for other
alkali halide clusters are discussed. (NaI)n clusters with n up to 15 do not
show yet a marked preference for geometries which are fragments of the bulk
lattice. Instead, stacks of hexagonal rings or more open structures are
obtained as ground structures in clusters with n=3, 6, 7, 9, 10, 12, 13 and 15,
indicating that convergence to bulk structure is not achieved yet at this size
range. Low lying isomers which are fragments of the crystal lattice exist,
nevertheless, for those cases. The binding energies show that clusters with
n=(4), 6, 9 and 12 molecules are specially stable. The binding energy has been
decomposed in contributions which allow for an intuitive interpretation. Some
electronic properties like ionization potentials and electronic energy levels
are also studied.

12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an