Abstract:
We use analytic methods to analyze the discrete spectrum for the problem
$(Z_1eZ_2)_2$ in the united-atom limit $(R\ll1)$ and obtain asymptotic
expansions for the quantum defect and energy terms of the system
$(Z_1eZ_2)_2$ at small intercenter distances $R$ up to terms of the order
$O(R^6)$. We investigate the effect of the dimensionality factor on the energy
spectrum of the hydrogen molecular ion H$^+_2$.
Keywords:planar problem of two Coulomb centers, boundary layer phenomena, confluent Heun equation, Mathieu functions, Ince equation.