Vv. Kostrykin et Aa. Kvitsinsky, EXACT AND AVOIDED CROSSINGS OF ADIABATIC HYPERSPHERICAL POTENTIAL CURVES, Journal of mathematical physics, 35(1), 1994, pp. 47-70
Exact crossing of potential curves related to the adiabatic hyperspher
ical (AH) approach to a three-body Coulomb system is studied. Analytic
structure of the AH potential curves, harmonics, and coupling matrix
elements near crossing points in the complex plane of hyperradius is i
nvestigated. Results are applied to derive some basic features of avoi
ded crossings of the AH potential curves at real hyperradii.