Group Theory for Chemists, 2nd Edition

APPENDIX 2

Microstates and Term Symbols

This brief overview sets out a stepwise strategy for determining the microstates for a given electronic configuration and how these are divided up into groups, each described by a term symbol. The microstates and term symbols for the d² configuration will be used as an example.

Step 1 : Determine the degeneracy of the configuration

This is done using eqn. 12. 1:

Step 2 : Determine the maximum L and S for the configuration

For each d-electron, m_l = 2, 1, 0, –1, –2, so maximum L = 4 (2 + 2). The two electrons can both have m_s = ½ so maximum S = 1.

Step 3 : Determine the range of M_L and M_S values associated ...