Mulliken Symbols for Irreducible Representations
(R. S. Mulliken, J. Chem. Phys., 1955, 23, 1997; 1956, 24, 1118)
| Symbol | Property |
|---|---|
| A | symmetric with respect to rotation around the principal rotational axis (one dimensional representations) |
| B | anti-symmetric with respect to rotation around the principal rotational axis (one dimensional representations) |
| E | degenerate (German: entartet; two dimensional representations, e.g. in systems with higher order principal axes) |
| subscript 1 | symmetric with respect to a vertical mirror plane perpendicular to the principal axis |
| subscript 2 | anti-symmetric with respect to a vertical mirror plane perpendicular to the principal axis |
| subscript g | symmetric with respect to a center of symmetry (German: "gerade") |
| subscript u | anti-symmetric with respect to a center of symmetry (German: "ungerade) |
| prime (') | symmetric with respect to a mirror plane horizontal to the principal rotational axis |
| double prime ('') | anti-symmetric with respect to a mirror plane horizontal to the principal rotational axis |
The standard convention taxes the Z-axis as the principal axis of the system and the YZ-plane as the principal plane.