Hyperfine structure in the B-X transition in I₂

This example reproduces figure 2 from S. Churassy, G. Grenet, M. L. Gaillard and R. Bacis, Opt. Comm. 30 41 (1979), and shows hyperfine structure from the spin 5/2 iodine nuclei in the 12-0 band of the B-X electronic transition of I₂. This shows how to handle hyperfine structure for equivalent nuclei; each nucleus should show in the constants tree, but AsNext is set true for the first nucleus so it is treated as equivalent to the second and all the constants are taken from the second nucleus.  JAdjustSym is also off, as it can give confusing results in this case.

The statistical weights are set to SymWt=1, AsymWt = 0, as there are no other equivalent nuclei in the molecule.   Note that this is a change introduced in 7.1.141; previous versions required both SymWt and AsymWt non zero, but did not handle the case of more than one pair of equivalent nuclei correctly.

If you don't want the hyperfine structure, set nNuclei to 0, and SymW = 5, AsymWt = 7 (or SymW = 15, AsymWt = 21) for the correct statistical weights.