Discreteness of spectrum and strict positivity criteria for magnetic   Schr\"odinger operators
  We establish necessary and sufficient conditions for the discreteness of spectrum and strict positivity of magnetic Schr\"odinger operators with a positive scalar potential. They are expressed in terms of Wiener's capacity and the local energy of the magnetic field. The conditions for the discreteness of spectrum depend on two functional parameters. One of them is a decreasing function of one variable whose argument is the normalized local energy of the magnetic field. This function enters the negligibility condition of sets for the scalar potential. We give a description for the range of admissible functional parameters which is precise in a certain sense.   In case when there is no magnetic field, our results extend the discreteness of spectrum and positivity criteria by A.Molchanov (1953) and V.Maz'ya (1973). 
Vladimir Kondratiev (Moscow State University), Vladimir Maz'ya   (Link\"oping University), Mikhail Shubin (Northeastern Univ...