  This article examines the suggestion made in Ref. [EPL, 115 (2016) 60001]
that a solution to a particle in an infinite spherical well model, if it is
square-integrable, is a physically valid solution, even if at the precise
location of the singularity there is no underlying physical cause, therefore,
the divergence would have to be a nonlocal phenomenon caused by confining walls
at a distance. In this work we examine this claim more carefully. By
identifying the correct differential equation for a divergent square-integrable
solution and rewriting it in the form of the Schroedinger equation, we infer
that the divergent wavefunction would be caused by the potential V(r)=-r
delta(r), which is a kind of attractive delta potential. Because of its
peculiar form and the fact that it leads to a divergent potential energy <V> =
- infinity, the potential V(r) and the divergent wavefunction associated with
it are not physically meaningful.
