Bound states in the Kratzer plus polynomial potentials and their new exact tractability via nonlinear algebraic equations

Abstract

Schroedinger equation with potentials of the Kratzer plus polynomial type (say, quartic V(r) = A r^4 +B r^3 + C r^2+D r + F/r + G/r^2 etc) is considered. A new method of exact construction of some of its bound states is then proposed. it is based on the Taylor series terminated rigorously after N+1 terms at specific couplings and energies. This enables us to find the exact, complete and compact unperturbed solution of the Magyari&#39;s N+2 coupled and nonlinear algebraic conditions of the termination in the strong-coupling regime with G \to \infty. Next, at G < \infty, we adapt the Rayleigh-Schroedinger perturbation theory and define the bound states via an innovated, triple perturbation series. In tests we show that all the correction terms appear in integer arithmetics and remain, therefore, exact.