In this paper, that the formula of cannot be tenable is pointed out because of the component of the momentum functor not always satisfying the self-adjointness in the curvilinear coordinate system.
指出由于在曲线坐标系中，动量算符的分量不一定满足自伴性，因而公式不能成立。
2
In this paper, we get the self-adjointness of the product operators generated by different two differential expressions by operator theory and matrix calculation.