Following the work of Guo, Thompson, and Sewell (Y.Guo, D.L.Thompson, and T.D. Sewell, J.Chem.Phys. 104, 576 (1996)) on the zero point energy correction of classical trajectories, we emphasize that the zero-point energy of a molecule is a quantum phenomenon with no classical counterpart, rooted soundly in the positionmomentum uncertainty principle. As a consequence certain quantum “ingredients,...