Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ab initio molecular dynamics simulations of negative thermal expansion
  in ScF3: the effect of the supercell size   Scandium fluoride (ScF3) belongs to a class of negative thermal expansion
(NTE) materials. It shows a strong lattice contraction up to about 1000 K
switching to expansion at higher temperatures. Here the NTE effect in ScF3 is
studied in the temperature range from 300 K to 1600 K using ab initio molecular
dynamics (AIMD) simulations in the isothermal-isobaric (NpT) ensemble. The
temperature dependence of the lattice constant, inter-atomic Sc-F-Sc bond angle
distributions and the Sc-F and Sc-Sc radial distribution functions is obtained
as a function of supercell size from 2a x 2a x 2a to 5a x 5a x 5a where a is
the lattice parameter of ScF3. A comparison with the experimental Sc K-edge
EXAFS data at 600 K is used to validate the accuracy of the AIMD simulations.
Our results suggest that the AIMD calculations are able to reproduce
qualitatively the NTE effect in ScF3, however a supercell size larger than 2a x
2a x 2a should be used to account accurately for dynamic disorder. The origin
of the NTE in ScF3 is explained by the interplay between expansion and rotation
of ScF6 octahedra.

11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph