The number of possible orientations, calculated as

, of
the spin
angular momentum corresponding to a given total spin quantum
number
(
), for the same spatial electronic wavefunction. A
state of singlet multiplicity has

and

.
A
doublet state has

,

,
etc. Note that when

(the total orbital
angular
momentum possible) there are only

orientations of total
angular momentum
possible.
Source:
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2255