标题: Symmetry Operation [打印本页] 作者: OLS 时间: 2009-2-2 22:45 标题: Symmetry Operation Symmetry Operation ; U! p& y: J5 m3 ESymmetry operations include the Improper Rotation, Inversion Operation, Mirror Plane, and Rotation. Together, these operations create 32 crystal classes corresponding to the 32 Point Groups. 5 D3 o1 b6 `0 O3 d, O1 Q+ M
The Inversion Operation takes 2 u" ]2 y9 b& M6 H7 D9 E(x,y,z)=>(-x,-y,-z)! T( x" i) V5 f" J+ z% O
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. 6 u) q* E7 A+ z; h- e+ f: T9 B9 M9 FThe Mirror Plane symmetry operation takes ; B+ [& H D5 a" x' S
(x,y,z)=>(x,y,-z)=>(x,-y,z)7 a( q3 v, V! c3 I ?& v$ j* P6 `/ @
etc., which is equivalent to 2.