Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superionic hydrogen in Earth's deep interior   Superionic hydrogen was previously thought to be an exotic state predicted
and confirmed only in pure H2O ice. In Earth's deep interior, H2O exists in the
form of O-H groups in ultra-dense hydrous minerals, which have been proved to
be stable even at the conditions of the core-mantle boundary (CMB). However,
the superionic states of these hydrous minerals at high P-T have not been
investigated. Using first-principles calculations, we found that pyrite
structured FeO2Hx (0 <= x <= 1) and d-AlOOH, which have been proposed to be
major hydrogen-bearing phases in the deep lower mantle (DLM), contain
superionic hydrogen at high P-T conditions. Our observations indicate a
universal pathway of the hydroxyl O-H at low pressure transforming to
symmetrical O-H-O bonding at high-P low-T, and a superionic state at high-P
high-T. The superionicity of hydrous minerals has a major impact on the
electrical conductivity and hydrogen transportation behaviors of Earth's lower
mantle as well as the CMB.

28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ