Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Aggregation of rod-like polyelectrolyte chains in the presence of
  monovalent counterions   Using molecular dynamics simulations, it is demonstrated that monovalent
counterions can induce aggregation of similarly charged rod-like
polyelectrolyte chains. The critical value of the linear charge density for
aggregation is shown to be close to the critical value for the
extended-collapsed transition of a single flexible polyelectrolyte chain, and
decreases with increasing valency of the counterions. The effective interaction
potential between two rod-like polyelectrolyte chains is measured, and is
related to the angular distribution of the condensed counterions.

20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg