We consider Bloch electrons on the honeycomb lattice under a uniform magnetic
field with 2Ï€p/q flux per cell. It is shown that the problem factorizes
to two triangular lattices. Treating magnetic translations as Heisenberg-Weyl
group and by the use of its irreducible representation on the space of theta
functions, we find a nested set of Bethe equations, which determine the
eigenstates and energy spectrum. The Bethe equations have simple form which
allows to consider them further in the limit p,q→∞ by the technique
of Thermodynamic Bethe Ansatz and analyze Hofstadter problem for the irrational
flux.Comment: 7 pages, 2 figures, Revte