Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Can hydrogen be stored inside carbon nanotubes under pressure in
  gigapascal range?   By using a newly fitted multi-parameter potential to describe the van der
Waals interaction between carbon and molecular hydrogen, we study the hydrogen
storage inside carbon nanotubes (CNT's) under pressure in gigapascal range.
Comparing with the results of graphite, we find that the shape change of the
nanotubes (the curvature effect) provides a different storage mechanism for
hydrogen. The negative free energy change for hydrogen storage inside CNT's
makes it possible to use CNT's as the nanocontainer [Carbon 45, 315 (2007)].

15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph