Rigid rotations in two-electrons atoms in a uniform magnetic field

Two exact rigid body solutions for a rotating two-electron atom under the influence of a magnetic field directed along the rotation axis were obtained using a classical approach. A solution gives at zero field the same result previously known as a rigid rotor. The other solution at zero field gives the previous result known as an asymmetric top or Langmuir solution. A stability analysis of the linearized motions near each of these equilibrium motions was made for different values of the magnetic field intensity. It was found that they are unstable but can exist during certain time for certain combinations of the magnetic field intensity and the angular momentum. The experimental realization of these classical states are the resonant states which would manifest in the spectrum as a subset of the quasi-Landau resonances. An examination of the energy levels near the ionization threshold shows that, in fact, they are similar to the quasi-Landau resonances. Also analytical expressions for the diamagnetic susceptibility of the two-excited states reported in this work were found. For the purpose of comparison, a study of the classical diamagnetism in one-electron atoms is presented. (author). 26 refs, 9 figs