Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Metallic Hydrogen: A Liquid Superconductor?   Metallic hydrogen is expected to exhibit remarkable physics. Of particular
interest in this work is the possibility of high-temperature superconductivity.
Comparing calculations of the superconducting critical temperatures of the
solid phase to melting temperatures over a range of pressures leads to an
interesting question: Will the solid, in a superconducting state, melt to a
liquid that remains a superconductor? In this work, the possibility of liquid
superconductivity in metallic hydrogen is investigated. This is done by
first-principles simulations, and using the results of these to solve the
Eliashberg equations. These are carried out over the pressure (and temperature)
conditions where molecular dissociation is expected to first occur in the solid
phase. Over the pressure range $386.8(4)$--$783.7(4)$ GPa, $T_c$ increases from
$308(6)$ to $372(2)$ K with a maximum uncertainty of $10$ K; it then decreases
to $356(2)$ K at $883.7(3)$ GPa. Comparisons to the solid phase show that the
critical temperature is not significantly changed between the two phases,
though the physics behind their superconductivity is different. Careful
comparisons of these values to recent results in the context of the hydrogen
phase diagram show that they are higher than the melting temperatures and that
the solid will melt to liquid atomic hydrogen. The results of this work (in
this context) therefore suggest that liquid atomic hydrogen will indeed exist
in a superconducting state. They also provide the pressure and temperature
conditions over which to look for it.

17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org