Basic introduction of space lattice
A space lattice is also called a "space lattice". It is usually synonymous with "spatial lattice". It is an infinite three-dimensional geometric figure connected by a series of geometric points (called nodes) that are regularly and repeatedly arranged in three-dimensional space. It is abstracted from a specific crystal structure. The regularity of the arrangement of nodes in the space lattice reflects the regularity of the spatial distribution of atoms, ions or molecules in the crystal structure. The nodes arranged on a straight line are connected into rows and columns. The distance between adjacent nodes on the rows and columns is called the node distance. In parallel rows and columns, the node spacing must be equal. The nodes distributed on a plane are connected into a mesh. The number of nodes in a unit area of a mesh is called the mesh density. The distance between two adjacent parallel meshes is the mesh distance. The surface mesh density and surface mesh spacing of parallel meshes must be all the same. A space lattice can always be divided into a series of parallelepipeds stacked parallel to each other by three groups of intersecting surface nets to show a lattice shape. If the divided parallelepiped can reflect the symmetry of the entire space lattice, the right-angle relationship is as much as possible and the volume is the smallest. Such a parallelepiped is called a unit parallelepiped. According to the different symmetry of the unit parallelepiped, the space lattice belongs to seven crystal systems respectively; according to the distribution of the nodes in the unit parallelepiped, the space lattice can be divided into the original lattice, the bottom center lattice, the body center lattice, and Face-centered lattice four possible types. In this way, there are 14 different types of spatial lattices in the crystal, which are commonly referred to as 14 Bravi space lattices, also known as 14 translational lattices or moving lattices.