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The theory section (narrow energy band theory) could use some clarification. I don't have the expertise to do it myself, but in addition to just trying to improve flow and readability, I have a couple specific recommendations: (1) There are references to "The more general band theories" and "the usual band theories." Not sure what those refer to; links to the articles describing them would be helpful. (2) The material talking about what this model explains should be separated at least into another paragraph, if not a whole different section. 18.104.22.168 (talk) 22:29, 10 December 2015 (UTC)