The Correlation of Molecular and Atomic Electronic States

APPENDIX C. The Correlation of Molecular and Atomic Electronic States 

The A values resulting from the combination of Lj and the orbital quantum numbers of two unlike atoms, are 

If A 0, each state is doubly degenerate, a degeneracy removed by rotational interaction to give A doubling. When /I = 0, if Lj + 2 + /i + X 4 is even there will be one more 27+ state than 27 state and if it is odd, one more 27 state than 27+ state. 

The molecular spin S will take all values from to S — 

For homonuclear diatomic molecules the combination of different states proceeds as for heteronuclear molecules except that each molecular state occurs with both parities. However, like atomic states give rise to the same molecular state multiplicities as for heteronuclear molecules but the A and parity values are a function of the spin S as follows. 

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Mulliken, R. S. 1928a. The assignment of quantum numbers for electrons in molecules. 11. The correlation of molecular and atomic electron states. Physical Review 32 761-772. 

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