Helium-Like Atoms in Magnetic Fields of Arbitrary Strengths

As shown in the previous chapters our knowledge of hydrogen-like systems in magnetic fields of arbitrary strength is fairly good and complete although at some points further investigations are necessary. By contrast the knowledge of atomic data for helium-like atoms in strong magnetic fields is much more fragmentary. In those atoms the nonseparability of the three-body problem appears as an additional complicating fact to the competing symmetries of the Coulomb and Lorentz forces. As already discussed in our historical review in Sect. 1.2 only the lowest triplet and singlet states have been treated in some detail so far.