标题: Symmetry Operation [打印本页] 作者: OLS 时间: 2009-2-2 22:45 标题: Symmetry Operation Symmetry Operation 5 G- l9 d! r: `* U) T
Symmetry operations include the Improper Rotation, Inversion Operation, Mirror Plane, and Rotation. Together, these operations create 32 crystal classes corresponding to the 32 Point Groups. ; P0 C1 B' z9 {" X: j2 WThe Inversion Operation takes 0 q4 l) U" v0 {, e, m2 b6 g
(x,y,z)=>(-x,-y,-z)( }/ `, V6 z( U
and is denoted i. When used in conjunction with a Rotation, it becomes an Improper Rotation. An Improper Rotation by 360/n . For periodic crystals, the Crystallography Restriction allows only the Improper Rotations 1, 2, 3, 4, and 6. & ]# F6 C& c) p4 X4 _0 x7 XThe Mirror Plane symmetry operation takes ' J ?# i! F8 _2 B8 X4 y1 M* d
(x,y,z)=>(x,y,-z)=>(x,-y,z)( i7 z* J8 Z+ |! |4 m
etc., which is equivalent to 2.