Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Understanding Nanopore Window Distortions in the Reversible Molecular
  Valve Zeolite RHO   Molecular valves are becoming popular for potential biomedical applications.
However, little is known concerning their performance in energy and
environmental areas. Zeolite RHO shows unique pore deformations upon changes in
hydration, cation siting, cation type, or temperature-pressure conditions. By
varying the level of distortion of double eight-rings, it is possible to
control the adsorption properties, which confer a molecular valve behavior to
this material. We have employed interatomic potentials-based simulations to
obtain a detailed atomistic view of the structural distortion mechanisms of
zeolite RHO, in contrast with the averaged and space group restricted
information provided by diffraction studies. We have modeled four
aluminosilicate structures, containing Li$^+$, Na$^+$, K$^+$, Ca$^{2+}$, and
Sr$^{2+}$ cations. The distortions of the three different zeolite rings are
coupled, and the six- and eight-membered rings are largely flexible. A large
dependence on the polarizing power of the extra-framework cations and with the
loading of water has been found for the minimum aperture of the eight-membered
rings that control the nanovalve effect. The calculated energy barriers for
moving the cations across the eight-membered rings are very high, which
explains the experimentally observed slow kinetics of the phase transition as
well as the appearance of metastable phases.

8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
19
The categories of this paper are: eess