Bernhard Baumgartner, Robert Seiringer
On the ordering of energy levels in homogeneous magnetic fields
(38K, LaTeX2e)

ABSTRACT.  We study the energy levels of a single particle 
in a homogeneous magnetic field and in an axially symmetric external potential. 
For potentials that are superharmonic off the central axis, 
we find a general ``pseudoconcave'' ordering of the ground state energies of the Hamiltonian restricted to 
the sectors with fixed angular momentum. 
The physical applications include 
atoms and ions in strong magnetic fields. There the energies are monotone 
increasing and concave in angular momentum. 
In the case of a periodic chain of atoms the pseudoconcavity 
extends to the entire lowest band of Bloch functions.