Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stable spatially discrete envelope-function model for graphene-like band
  structures   The spurious states found in numerical implementations of envelope function
models for semiconductor heterostructures and nanostructures have been shown to
be readily removed by employing a first-order difference scheme. This approach
is applied to the band structure of graphene. The massless Dirac equation is
identical to a simple two-band model with zero energy gap. A first-order
discretization of this equation produces strictly monotonic dispersion
relations with the desired linear dependence on k near the origin, thus
removing the "fermion doubling" anomaly associated with formulation on a
computational mesh. The first-order formulation produces an ambiguity in the
form of the Hamiltonian; both forms produce identical results for physical
observeables, and are related by both unitary transformations and time
reversal. Other details needed to evaluate the properties of current-carrying
systems, including current density expressions, open boundary conditions and
the treatment of heterojunctions, are also developed.

37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph