| Abstract: | An extremum principle was postulated by Horne, Finkelstein, Shull, Zeilinger, and Bernstein in order to derive the physically allowable parameters for sinusoidal standing waves governing a neutron in a crystal which is immersed in a strong external magnetic field:  the expectation value of the total potential  V is an extremum. We show that this extremum principle can be obtained from the variational principle used by Schrodinger to derive his nonrelativistic wave equation. We rederive the solutions found by the above-mentioned authors as well as some additional solutions. |
