An extremum principle for a neutron diffraction experiment

An extremum principle was postulated by Horne, Finkelstein, Shull, Zeilinge r, and Bernstein in order to derive the physically allowable parameters for sinusoidal standing waves governing a neutron in a crystal which is immers ed in a strong external magnetic field. "the expectation value of the total potential [V] is nn extremum." We show that this extremum principle can be obtained from the variational principle risen hy Schrodinger to derive his nonrelativistic wave equation. We rederive the solutions found by the abov e-mentioned authors as well as same additional solutions.