1/N-Expansion in Quantum Mechanics

Abstract

WKB-approximation often produces result with high accuracy and at the quantum numbers $n\sim 1,$ though formally the condition of its applicability is $n\gg 1.$ Choice of parameter $N$ is usually connected with the increasing of number of states, or degrees of freedom of the considered system, dimension of space, and so on. Below we consider some simple examples of such approach for the solution of single-particle Schr ödinger equation.