**
Below is the ascii version of the abstract for 03-531.
The html version should be ready soon.**Yulia Karpeshina
Spectral Properties of the Periodic Magnetic Schr\"{o}dinger Operator
in the High-Energy Region. Two-Dimensional Case.
(797K, Postscript)
ABSTRACT. The goal is to investigate spectral properties of the operator
$H=(-i\nabla +\vec a(x))^2+a_0(x)$ in the two-dimensional situation, $(\vec a(x), a_0(x))$ being
periodic. We construct asymptotic formulae for Bloch eigenvalues and eigenfunctions in the
high-energy region, describe properties
of isoenergetic curves in the space of quasimomenta and give a new proof of the Bethe-Sommerfeld
conjecture.