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 i4 w/ Q1 h; ?$ ]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. : a5 M% Z& g+ D3 z* o) }# eThe Inversion Operation takes 4 E* p+ _ {+ _" b9 Q
(x,y,z)=>(-x,-y,-z)4 d$ ^4 v* U3 k2 ^: 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. + Z# p$ U& \1 a- }8 A: \: a5 c
The Mirror Plane symmetry operation takes / c( q$ Q' v& j6 D( ~4 N2 D- ?(x,y,z)=>(x,y,-z)=>(x,-y,z)7 y1 X+ p* f U- |% [3 T
etc., which is equivalent to 2.