iOpenShell » Q-Chem specific questions » Anharmonic IR intensities?

Anharmonic IR intensities?

Page: 1

Author Post
Member
Registered: Jul 2015
Posts: 3
I have done a VCI[2] calculation to obtain anharmonic energies for a particular molecule, as I suspect that I am seeing some overtones involving fairly anharmonic intermolecular interactions in an experimental spectrum that I am analyzing. While this has given me quite a few candidates for assigning these features just based on the anharmonic energies, I would be interested in calculating the transition intensities for the anharmonic levels. Is there a way to get QChem to do this, or is there a way that I can calculate them myself from the VCI[2] results?
Member
Registered: Jul 2015
Posts: 3
Also, regarding the VCI[2] output, it seems to have given me two separate energies for the same vibrational level (first and last lines of the block below):

VCI[2] | 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1265.29
VCI[2] | 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1268.32
VCI[2] | 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1277.75
VCI[2] | 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1303.67
VCI[2] | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1304.90
VCI[2] | 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1306.95
VCI[2] | 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1314.34
VCI[2] | 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1316.05
VCI[2] | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1321.53
VCI[2] | 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1330.96
VCI[2] | 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 1334.30

Does anyone have any suggestions of what that means? I'm a bit perplexed by it.

Page: 1

iOpenShell » Q-Chem specific questions » Anharmonic IR intensities?