Modern Physics for Engineers Lecture slides 13c – Emergence of bands

This lecture part illustrates how, when we bring N identical potential wells (or atoms) together, the individual well or atomic energy levels split into N different coupled energy levels, which we can view as forming a "band" of energies or states. These wavefunctions tend to be a product of a "unit cell" function that is approximately the same in each unit cell or period, and a larger envelope function, which is approximately a large sinusoid. (slides)