Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nature of extrinsic and intrinsic self-trapping of charge carriers in
  underdoped cuprate high-$T_\text{c}$ superconductors   Nature of extrinsic and intrinsic self-trapping (ST) of charge carriers in
cuprates have been studied theoretically. The binding energies and radii of the
extrinsic and intrinsic large polarons and bipolarons in cuprates are
calculated variationally using the continuum model and adiabatic approximation.
We have shown that the extrinsic and intrinsic three-dimensional (3D) large
bipolarons exist in underdoped cuprates at
$\eta=\varepsilon_{\infty}/\varepsilon_0<0.127$ and $\eta<0.138$, respectively
[where $\varepsilon_{\infty}$ ($\varepsilon_0$) is the optic (static)
dielectric constant].

13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
1
The categories of this paper are: cs