A Description of the Rotator as an Example of Hamiltonian with Coordinate-Dependent Mass ---Semi-Classical Theory---
A description of the rotator is given as an example of large amplitude oscillation. The basic idea is a quasi-harmonic approximation proposed by the present author. Classical solution is quantized in the framework of the old quantum theory. The results are qualitatively consistent with the exact ones in the region from the small to the large amplitude.