|
In geometry and crystallography, a Bravais lattice, studied by , is an infinite array of discrete points generated by a set of discrete translation operations described by: : where ''ni'' are any integers and ai are known as the primitive vectors which lie in different directions and span the lattice. This discrete set of vectors must be closed under vector addition and subtraction. For any choice of position vector R, the lattice looks exactly the same. When the discrete points are atoms, ions, or polymer strings of solid matter, the ''Bravais lattice'' concept is used to formally define a ''crystalline arrangement'' and its (finite) frontiers. A crystal is made up of a periodic arrangement of one or more atoms (the ''basis'') repeated at each lattice point. Consequently, the crystal looks the same when viewed from any equivalent lattice point, namely those separated by the translation of one unit cell (the ''motive''). Two Bravais lattices are often considered equivalent if they have isomorphic symmetry groups. In this sense, there are 14 possible Bravais lattices in three-dimensional space. The 14 possible symmetry groups of Bravais lattices are 14 of the 230 space groups. ==Bravais lattices in at most two dimensions== In zero-dimensional and one-dimensional space, there is only one type of Bravais lattice. In two-dimensional space, there are five Bravais lattices: oblique, rectangular, centered rectangular, hexagonal (rhombic), and square. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bravais lattice」の詳細全文を読む スポンサード リンク
|