[Altered State]

Anyone could tell me if these irreducible representation calculations for trans-dichloroethene to figure out IR and Raman active vibrations are right?

Not having an atom in the center of the molecule confused me a bit, and made me get tons of zeros, so many terms cancel out and I ended up with a kinda strange result for me, who I'm starting to learn to do this (made just a few easy examples).

Here it is:
http://i.imgur.com/4oM0mlc.jpg
(I didn't instert it here because is quite big)

Thanks in advance


Edit:
The results are supposed to match with one of these 3 spectra:
http://i.imgur.com/ZELJs02.jpg

Since I got 4 IR active bands, might be the spectrum B, if we consider that "band" at 3300cm-1 as an impurity or intrumental thing.
But I hope someone could correct my calculations anyway even if that were a possitive result, since I'm starting to learn this.



Edit2: I think there is an error in the calculation of Gamma xyz, seems that I don't get how to calculate them properly. Any practical explanation that works in every case?

[Corribus]

Ok, we've got a lot of ground to cover. Let's start with your answer for Γ_vib. What do you expect your dimensionality to be?

[Altered State]

Ok, we've got a lot of ground to cover. Let's start with your answer for Γ_vib. What do you expect your dimensionality to be?

I guess 3N-6, which equals 12, and it's not what I got (
I think error is in χ^xyz
Don't really know a way to obtain these for any case.

[Corribus]

There are few methods to use to get your irreducible representation for vibration normal modes, and I think all of them are hard to explain on a message forum. Especially, I don't want to try to explain the way I usually use if you've been taught something else. That will only confuse you.

Take a look at this recent thread, particularly the method described in post 8, and see if that helps you out. Let me know if that's generally the way you've been taught to do it. If not, I'll try my best to help you out from scratch.

[Altered State]

There are few methods to use to get your irreducible representation for vibration normal modes, and I think all of them are hard to explain on a message forum. Especially, I don't want to try to explain the way I usually use if you've been taught something else. That will only confuse you.

Take a look at this recent thread, particularly the method described in post 8, and see if that helps you out. Let me know if that's generally the way you've been taught to do it. If not, I'll try my best to help you out from scratch.

I'm sorry, which thread are you talking about? I can't find anything related in the last page of this subforum nor in the inorganic chemistry one...

[Corribus]

Lol, sorry, forgot to paste the link.

http://www.chemicalforums.com/index.php?topic=73681.0

[Altered State]

Lol, sorry, forgot to paste the link.

http://www.chemicalforums.com/index.php?topic=73681.0

Holy ****, that was such a nice thread and explanations. I loved the most that last one that relates irreducible representations with actual physical vibrational modes.

I think I definitely got this, I'll post a complete answer tomorrow, to see if I'm correct.

Thank you very much