In mathematics and solid state physics, the first Brillouin zone is a uniquely defined primitive cell in reciprocal space. The boundaries of this cell are given by planes related to points on the reciprocal lattice. It is found by the same method as for the Wigner–Seitz cell in the Bravais lattice. The importance of the Brillouin zone stems from the Bloch wave description of waves in a periodic medium, in which it is found that the solutions can be completely characterized by their behavior in a single Brillouin zone.
Taking surfaces at the same distance from one element of the lattice and its neighbours, the volume included is the first Brillouin zone (see the derivation of the Wigner-Seitz cell). Another definition is as the set of points in k-space that can be reached from the origin without crossing any Bragg plane. Equivalently, this is the Voronoi cell around the origin of the reciprocal lattice.
There are also second, third, etc., Brillouin zones, corresponding to a sequence of disjoint regions (all with the same volume) at increasing distances from the origin, but these are used less frequently. As a result, the first Brillouin zone is often called simply the Brillouin zone. (In general, the n-th Brillouin zone consists of the set of points that can be reached from the origin by crossing exactly n − 1 distinct Bragg planes.)
A related concept is that of the irreducible Brillouin zone, which is the first Brillouin zone reduced by all of the symmetries in the point group of the lattice.
The concept of a Brillouin zone was developed by Léon Brillouin (1889–1969), a French physicist.
Several points of high symmetry are of special interest – these are called critical points.[1]
| Symbol | Description |
|---|---|
| Γ | Center of the Brillouin zone |
| Simple cube | |
| M | Center of an edge |
| R | Corner point |
| X | Center of a face |
| Face-centered cubic | |
| K | Middle of an edge joining two hexagonal faces |
| L | Center of a hexagonal face |
| U | Middle of an edge joining a hexagonal and a square face |
| W | Corner point |
| X | Center of a square face |
| Body-centered cubic | |
| H | Corner point joining four edges |
| N | Center of a face |
| P | Corner point joining three edges |
| Hexagonal | |
| A | Center of a hexagonal face |
| H | Corner point |
| K | Middle of an edge joining two rectangular faces |
| L | Middle of an edge joining a hexagonal and a rectangular face |
| M | Center of a rectangular face |
Other lattices have different types of high-symmetry points. They can be found in the illustrations below.
See below for the aflowlib.org standard.
See below for the aflowlib.org standard.
See below for the aflowlib.org standard.
See below for the aflowlib.org standard.
See below for the aflowlib.org standard.
See below for the aflowlib.org standard.
See below for the aflowlib.org standard.