Editing Electronic band structure (section)

=== Others ===
Calculating band structures is an important topic in theoretical [[solid state physics]]. In addition to the models mentioned above, other models include the following:
* [[Empty lattice approximation]]: the "band structure" of a region of free space that has been divided into a lattice.
* [[k·p perturbation theory]] is a technique that allows a band structure to be approximately described in terms of just a few parameters. The technique is commonly used for [[semiconductors]], and the parameters in the model are often determined by experiment.
* The [[Particle in a one-dimensional lattice (periodic potential)#Kronig–Penney model|Kronig–Penney model]], a one-dimensional rectangular well model useful for illustration of band formation. While simple, it predicts many important phenomena, but is not quantitative.
* [[Hubbard model]]

The band structure has been generalised to wavevectors that are [[complex number]]s, resulting in what is called a ''complex band structure'', which is of interest at surfaces and interfaces.

Each model describes some types of solids very well, and others poorly. The nearly free electron model works well for metals, but poorly for non-metals. The tight binding model is extremely accurate for ionic insulators, such as [[metal halide]] salts (e.g. [[Sodium chloride|NaCl]]).