PerlMol

I work in X-ray crystallography and it is quite common to have molecules,
say toluene, sitting on a crystallographic symmetry operator. This results
in fractional atoms when considering the unique formula. For instance, in
the unit cell is one molecule of C22H20F3N7O3S1 and a toluene (on a
symmetry centre) making the unit cell formula C51H48F6N14O6S2 (Z=2). The
elemental formula is then C25.5 H24 F3 N7 O3 S1.

It would be very useful if Chemistry::Mol understood and dealt with
formulae such as C25.5 H24 F3 N7 O3 S1 or 0.5(C51H48F6N14O6S2)