Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Incipient Metals: Functional Materials with a Unique Bonding Mechanism   While solid-state materials are commonly classified as covalent, ionic, or
metallic, there are cases that defy these iconic bonding mechanisms. A
prominent example is given by phase-change materials (PCMs) for data storage or
photonics, which have recently been argued to show 'resonant' bonding; a clear
definition of this mechanism, however, has been lacking until the present day.
Here we show that these solids are clearly different from resonant bonding in
the pi-orbital systems of benzene and graphene. Instead, they exhibit a unique
mechanism between covalent and metallic bonding, which we call 'metavalent'
bonding. The materials are on the verge of electron delocalization, which
explains their exceptional property portfolio, and we therefore argue that they
represent 'incipient metals'. This yields deeper, fundamental insight into the
bonding nature of solid-state materials, and is expected to accelerate the
discovery and design of new functional materials including PCMs and
thermoelectrics.

17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
16
The categories of this paper are: stat