Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum molecular dynamics simulations of thermophysical properties of
  fluid ethane   We have performed first-principles molecular-dynamics simulations based on
density-functional theory to study the thermophysical properties of ethane
under extreme conditions. We present new results for the equation of state of
fluid ethane in the warm dense region. The optical conductivity is calculated
via the Kubo-Greenwood formula from which the dc conductivity and optical
reflectivity are derived. The close correlation between the nonmetal-metal
transition of ethane and its decomposition, that ethane dissociates
significantly into molecular and/or atomic hydrogen and some long alkane
chains, has been systematically studied by analyzing the optical conductivity
spectra, pair correlation functions, electronic density of states and charge
density distribution of fluid ethane.

1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th