Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Melting in large sodium clusters: An orbital-free molecular dynamics
  study   The melting-like transition in sodium clusters Na_N, with N=55, 92, and 142
is studied by using constant-energy molecular dynamics simulations. An
orbital-free version of the Car-Parrinello technique is used which scales
linearly with system size allowing investigation of the thermal behaviour of
large clusters. The ground state isomer of Na_142 (an uncomplete three-shell
icosahedron) melts in two steps: the first one (at approx. 240 K) is
characterized by the high mobility of the atoms located on the cluster surface;
the second, homogeneous melting (at approx. 270 K), involves diffusive motion
of all the atoms across the cluster. For the case of Na_92, the icosahedral
structure has a larger number of surface vacancies, and melts in two well
separated steps, surface melting at approx. 130 K and homogeneous melting at
approx. 240 K. Na_55, a complete two-shell icosahedron, melts in a single stage
at approx. 190 K. Our results on homogeneous melting for Na_142 and Na_92 are
in excellent agreement with recent experimental determinations of melting
temperatures and latent heats. However, the experimentally observed enhancement
of the melting temperature around N=55 is not reproduced by the calculations.

31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph