Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Role of the radiation-reaction electric field in the optical response of
  two-dimensional crystals   A classical theory of a radiating two-dimensional crystal is proposed and an
expression for the radiative-reaction electric field is derived. This field
plays an essential role in connecting the microscopic electromagnetic fields
acting on each dipole of the crystal to the macroscopic one, via the boundary
conditions for the system. The expression of the radiative-reaction electric
field coincides with the macroscopic electric field radiating from the crystal
and, summed to the incident electric field, generates the total macroscopic
electric field.

12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn