Frozen planet model

Camus et a/.34 explained their observations by a picture which has sometimes been called the frozen planet model. Qualitatively, the relatively slowly moving outer electron produces a quasi-static field at the inner electron given by l/rc2, and this field leads to the Stark effect in Ba+. The field allows the transitions to the n >n0Z and ,f 0 states and leads to shifts of the ionic energies. The presence of the njpn0f and n in0t resonances in the spectrum of Fig. 23.12 is quite evident. Camus et al. compared the shifts to those calculated in a fashion similar to a Bom-Oppenheimer calculation. With the outer electron frozen in place at ra they calculated the Ba+ energies, W,(rQ), and wavefunctions. They then added the energy W0(r0) to the normal screened coulomb potential seen by the outer electron. This procedure leads to a phase shift in the outer electron wavefunction... 

The frozen planet model is simple and physically appealing. In addition, it is clearly related to the treatment based on + and - states originally given by Cooper et al.2 The most convincing demonstrations of the legitimacy of the frozen... 

The frozen planet model also agrees with classical calculations of Richter and Wintgen,39 who find a classically stable state in which both electrons are on the same side of the atom in orbits which exhibit pronounced angular correlation, even though the orbital radii of the two electrons are very different. 

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