1307.5141 (R. G. Novikov et al.)

Two-dimensional von Neumann--Wigner potentials with a multiple positive
eigenvalue    [PDF]

R. G. Novikov, I. A. Taimanov, S. P. Tsarev

By the Moutard transformation method we construct two-dimensional Schrodinger operators with real smooth potential decaying at infinity and with a multiple positive eigenvalue. These potentials are rational functions of spatial variables and their sines and cosines.

View original: http://arxiv.org/abs/1307.5141