|Posted on Tuesday, February 17, 2015 - 8:21 am: |
Hello. I recently downloaded 15.0.002 and am using it with mopac 7 to look at vibrational frequencies. The computed intensities all come out equal to zero, and the computed IR spectrum is blank when you look at it. The animations of the different vibrational modes look just fine.
Oh yes, I have also tried an older WebMO (v13) with the mopac 7 vibrational calculations, and everything looks good there ...
Post Number: 445
|Posted on Tuesday, February 17, 2015 - 11:12 am: |
This is a MOPAC 7 "bug" that was exposed in a recent update of WebMO 15. It is resolved in WebMO 15.0.003. (Basically, MOPAC 7 doesn't bother to calculate the intensities with certain keyword combinations!)
|Posted on Tuesday, February 17, 2015 - 12:30 pm: |
Thanks for the reply. I saw some strange stuff on the WebMO demo server also, which is apparently running mopac2009. The vibrational intensities returned are strange, for example there is a strong band reported for the CO2 symmetric stretch, which results in no dipole moment change, and should not show up at all in the IR spectrum.
Post Number: 446
|Posted on Tuesday, February 17, 2015 - 2:13 pm: |
I will need to check this for more recent version of MOPAC (e.g. 2012+). The issue is that MOPAC is OMITTING vibration 1 in the output, for reasons I don't understand.