Playing Quantum Physics Jeopardy with zero-energy eigenstates
  We describe an example of an exact, quantitative Jeopardy-type quantum mechanics problem. This problem type is based on the conditions in one-dimensional quantum systems that allow an energy eigenstate for the infinite square well to have zero curvature and zero energy when suitable Dirac delta functions are added. This condition and its solution are not often discussed in quantum mechanics texts and have interesting pedagogical consequences. 
L. P. Gilbert, M. Belloni, M. A. Doncheski and R. W. Robinett