Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Born von Karman boundary condition is a set of boundary conditions which impose the restriction that a wave function must be periodic on a certain Bravais lattice. This condition is often applied in solid state physics to model an ideal crystal. The Born-von Karman boundary condition is important in solid state physics for analyzing many features of crystals, such as diffraction and the band gap. Modeling the potential of a crystal as a periodic function with the Born-von Karman boundary condition and plugging in Schroedinger''s equation results in a proof of Bloch''s theorem, which is particularly important in understanding the band structure of crystals.