Paper contains description of the fields nonlinear modes successive quantization scheme. It is shown that the path integrals for absorption part of amplitudes are defined on the Dirac ($\d$-like) functional measure. This permits arbitrary transformation of the functional integral variables. New form of the perturbation theory achieved by mapping the quantum dynamics in the space $W_G$ of the ({ \it action, angle})-type collective variables. It is shown that the transformed perturbation theory contributions are accumulated exactly on the boundary $\pa W_G$. Abilities of the developed formalism are illustrated by the Coulomb problem. This model is solved in the $W_C$=({ \it angle, angular momentum, Runge-Lentz vector}) space and the reason of its exact integrability is `emptiness' of $\pa W_C$.
Categories: hep-th