هنا تعريفات عن عناصر التماثل و كيفية ايجادها :
Symmetry Operation:A well-defined, non-translational movement of an object that produces a new orientation that is indistinguishable from the original object.
Symmetry Element:A point, line or plane about which the symmetry operation is performed.
Five kinds of Symmetry Elements and Symmetry Operations Required in Specifying Molecular Symmetry
* Identity (E)
Mirror plane (s)
Center of symmetry or center of inversion (i)
* Improper (rotation) axis (Sn)
Principal rotation axis – the Cn axis that has the highest value of n of multiple rotation axes exist.
C2 passes through several atoms and C2 passes between the C2 axes and the atoms.
Note: The principal axes is usually chosen as the z-axis.
* sh : mirror planes perpendicular to the principal axis.
*sv : mirror planes containing the principal axis Unless it is sd.
* sd : mirror planes bisecting x, y, or z axis or bisecting C2 axes perpendicular to the principal axis.