[qcan375]

Hi everyone,

I have a question regrading symmetry operations.

In determining the IR/Raman spectra for XeF4 using the symmetry operation for point group D4h, I was generating the irreducible representations (IRR). For the B1g IRR, I get 1/2 in which I do not understand what it means? I assumed all the IRRs should be whole integers. I get fraction values for the other B IRRs but not for the A or the E IRRs for this point group.

Really appreciate it if anyone can give advice on this probem.

Thank you.  

[lemonoman]

If you're calculating these irreducible representations (IRRs) from a reducible representation (RRs)...then you may be getting a fractional value if you calculated the order of the group incorrectly.

First try calculating the order of the point group again...make sure you're doing it the right way...if that fails, a (somewhat complicated but detailed) explanation can be found at http://www.chemsoc.org/ExemplarChem/entries/2004/hull_booth/PredictingSpectra/reduction_formula.htm

D4h group can be found at http://www.phys.ncl.ac.uk/staff/njpg/symmetry/D4h.html

[qcan375]

Thanks for the website (cool applets/animations) lemonoman, I saw what I was doing wrong.

Really appreciate it.