Ground and doubly excited states of two-dimensional D⁻ centers

Using hyperspherical coordinates and assuming the quasiseparability of the hyperradius R from the angular variables Ω in the wave functions, we obtain the low-lying adiabatic channel potentials U_μ(R) for the two-dimensional D⁻ centers. In the large-R limit, these potential curves converge to the thresholds of the energy levels of the neutral donor. The energy eigenstates supported by these potentials are calculated. The correlation patterns in these channels and the effect of symmetry are investigated.