Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A simple thermodynamic model for the hydrogen phase diagram   We describe a classical thermodynamic model that reproduces the main features
of the solid hydrogen phase diagram. In particular, we show how the general
structure types that are found by electronic structure calculations and the
quantum nature of the protons can also be understood from a classical
viewpoint. The model provides a picture not only of crystal structure, but also
for the anomalous melting curve and insights into isotope effects, liquid
metallisation and InfraRed activity. The existence of a classical picture for
this most quantum of condensed matter systems provides a surprising extension
of the correspondence principle of quantum mechanics, in particular the
equivalent effects of classical and quantum uncertainty.

19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys