Vol 3 - Landau, Lifshitz - Quantum mechanics - non-relativistic theory (3ed., 1991) · Problem 48.1

The Quasi-Classical Case

Physics — Landau & Lifshitz · quasi-classical-phase-space-states

Problem

Determine (approximately) the number of discrete energy levels of a particle moving in an arbitrary (not central) field

U(\mathbf{r})

which satisfies the quasi-classical condition.