2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/89060The textbook treatment in that the wave function of a dynamical system is expanded in an eigenfunction series is investigated. With help of an elementary example and some mathematical theorems, it is revealed that in terms of solving the time-dependent Schrödinger equation the treatment involves in divergence trouble . The root reason behind the trouble is finally analyzed.11 pages, 2 figures, LatexQuantum Physicstext