Abstract
Zak has recently pointed out apparent inconsistencies in the formulation of problems involving periodic systems, and he has questioned whether the commonly accepted correspondence between quantum mechanical and classical variables holds for such systems. We show that the difficulties found with periodic systems arise equally in nonperiodic systems, and that the problems encountered in defining certain quantum-mechanical observables are related to the ill-defined nature of the corresponding classical variables.
- Received 26 March 1970
DOI:https://doi.org/10.1103/PhysRevD.2.3079
©1970 American Physical Society