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The hexagonal lattice (sometimes called triangular lattice) is one of the five two-dimensional Bravais lattice types. [1] The symmetry category of the lattice is wallpaper group p6m. The primitive translation vectors of the hexagonal lattice form an angle of 120° and are of equal lengths,
The Bravais lattice concept is used to formally define a crystalline arrangement and its (finite) frontiers. A crystal is made up of one or more atoms, called the basis or motif, at each lattice point. The basis may consist of atoms, molecules, or polymer strings of solid matter, and the lattice provides the locations of the basis.
28 Αυγ 2022 · Bravais Lattice. The Bravais lattice is the basic building block from which all crystals can be constructed. The concept originated as a topological problem of finding the number of different ways to arrange points in space where each point would have an identical “atmosphere”.
In summary, there are five distinct 2-d Bravais lattices: (1) primitive oblique; (2) primitive rectangular; (3) centered rectangular; (4) primitive tetragonal; and (5) primitive trigonal and hexagonal (same lattice due to inversion).
The rhombohedral system has a three-fold axis, which constrains all the unit cell edges and angles to be equal, and the hexagonal system has a six-fold axis, which constrains the a and b lattice dimensions to be equal and the angle between them to be 120º.
Bravais lattices are point lattices that are classified topologically according to the symmetry properties under rotation and reflection, without regard to the absolute length of the unit vectors. A more intuitive definition: At every point in a Bravais lattice the “world” looks the same.