Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Orientationally ordered aggregates of stiff polyelectrolytes in the
  presence of multivalent salt   Aggregation of stiff polyelectrolytes in solution and angle- and
distance-dependent potential of mean force between two like-charged rods are
studied in the presence of 3-valent salt using molecular dynamics simulations.
In the bulk solution, formation of long-lived metastable structures with
similarities to the raft-like structures of actin filaments is observed within
a range of salt concentration. The system finally goes to a state with lower
free energy in which finite-sized bundles of parallel polyelectrolytes form.
Preferred angle and interaction type between two like-charged rods at different
separations and salt concentrations are also studied, which shed some light on
the formation of orientationally ordered structures.

20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th