Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diffusion on a heptagonal lattice   We study the diffusion phenomena on the negatively curved surface made up of
congruent heptagons. Unlike the usual two-dimensional plane, this structure
makes the boundary increase exponentially with the distance from the center,
and hence the displacement of a classical random walker increases linearly in
time. The diffusion of a quantum particle put on the heptagonal lattice is also
studied in the framework of the tight-binding model Hamiltonian, and we again
find the linear diffusion like the classical random walk. A comparison with
diffusion on complex networks is also made.

8
The categories of this paper are: hep-ex
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math