Diverging perturbation-theory series and classical mechanics
Popov V. S., Vainberg V. M., Mur V. D.
A summation of the diverging perturbation-theory series yields expressions for the energies of levels (real, virtual, and quasistationary) in terms of the coefficients of the perturbation theory, Ek. Taking the limit of classical mechanics reveals the asymptotic behavior of the highly excited levels with l = n— 1> 1, confirming the results of the summation of the perturbation-theory series.