The Kronig-Penney approximation: may it live on

The Kronig-Penney approximation is often used in introducing the concept of energy band structures in semiconductors to graduate electrical engineering students. The authors show that no essential information is lost in making this approximation. This fact, coupled with the approximation's recognized ability to produce analytical solutions to a difficult problem, leads the authors to conclude that it is premature to suggest the approximation is obsolete, as was suggested in a recent paper by A. Nussbaum (see ibid., vol.E-29, p.12-15, 1986).<
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