标题: Symmetry Operation [打印本页] 作者: OLS 时间: 2009-2-2 22:45 标题: Symmetry Operation Symmetry Operation ( {8 d" d5 P( }4 FSymmetry operations include the Improper Rotation, Inversion Operation, Mirror Plane, and Rotation. Together, these operations create 32 crystal classes corresponding to the 32 Point Groups. N. G& k1 r( U5 `) @( ^9 t8 T2 iThe Inversion Operation takes Q. K3 R4 ]* x4 f(x,y,z)=>(-x,-y,-z) ' n4 F4 G- X/ v4 B 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. % D4 n9 J( Z$ H K
The Mirror Plane symmetry operation takes ) X! q6 m/ M3 }* ~/ \1 M+ T
(x,y,z)=>(x,y,-z)=>(x,-y,z)3 R2 d; i0 m- Y2 r) e& f g1 G5 y
etc., which is equivalent to 2.