Editing Electronic band structure (section)

=== KKR model ===
{{Main|Multiple scattering theory}}
The KKR method, also called "multiple scattering theory" or Green's function method, finds the stationary values of the inverse transition matrix T rather than the Hamiltonian. A variational implementation was suggested by [[Jan Korringa|Korringa]], [[Walter Kohn|Kohn]] and Rostocker, and is often referred to as the ''[[Korringa–Kohn–Rostoker method]]''.<ref name=Galsin>{{cite book |title=Impurity Scattering in Metal Alloys |author=Joginder Singh Galsin |page=Appendix C |url=https://books.google.com/books?id=kmcLT63iX_EC&q=KKR+method+band+structure&pg=PA498 |isbn=978-0-306-46574-1 |year=2001 |publisher=Springer |no-pp=true}}</ref><ref name=Ohtaka>{{cite book |title=Photonic Crystals |author=Kuon Inoue, Kazuo Ohtaka |page=66 |url=https://books.google.com/books?id=GIa3HRgPYhAC&q=KKR+method+band+structure&pg=PA66 |isbn=978-3-540-20559-3 |year=2004 |publisher=Springer}}</ref> The most important features of the KKR or Green's function formulation are (1) it separates the two aspects of the problem: structure (positions of the atoms) from the scattering (chemical identity of the atoms); and (2) Green's functions provide a natural approach to a localized description of electronic properties that can be adapted to alloys and other disordered system. The simplest form of this approximation centers non-overlapping spheres (referred to as ''muffin tins'') on the atomic positions. Within these regions, the potential experienced by an electron is approximated to be spherically symmetric about the given nucleus. In the remaining interstitial region, the [[Screening effect|screened potential]] is approximated as a constant. Continuity of the potential between the atom-centered spheres and interstitial region is enforced.