© 1999 by London Mathematical Society
© The London Mathematical Society
A Minimax Principle for the Eigenvalues in Spectral Gaps
Mathematik, Universität Regensburg D-93040 Regensburg, Germany Marcel.Griesemer{at}mathematik.uni-regensburg.de
Mathematik, Universität Regensburg D-93040 Regensburg, Germany Heinz.Siedentop{at}mathematik.uni-regensburg.de
Received 4 December 1997.
A minimax principle is derived for the eigenvalues in the spectral gap of a possibly non-semibounded self-adjoint operator. It allows the nth eigenvalue of the Dirac operator with Coulomb potential from below to be bound by the nth eigenvalue of a semibounded Hamiltonian which is of interest in the context of stability of matter. As a second application it is shown that the Dirac operator with suitable non-positive potential has at least as many discrete eigenvalues as the Schrödinger operator with the same potential.