CCL:G: Determining whether a transition is n-pi* or pi-pi*
From: "John McKelvey" <jmmckel:gmail.com>
Subject: CCL:G: Determining whether a transition is n-pi* or
pi-pi*
Date: Fri, 22 Aug 2008 12:26:31 -0400
One immediate check is whether or not the computed oscillator
strength is exactly 0, which it should be for n-pi* for D2h in something like
D2h p-quinone, or tetra-aza benzene or naphthalene, for example.
Sent to CCL by: "Matthew K Morantz" [matthew.morantz-.-gmail.com]
Hi,
Just a quick and simple question:
I've optimized a D2h-symmetry molecule at the DFT-B3LYP-6/31G level of
theory in Gaussian. I've figured out the HOMO-LUMO gap from the orbital
energies.
I'm now attempting to correlate this gap with the experimental max of the
molecule.
I know that E(HOMO-LUMO) = E(lambdamax) = hv and have calculated
E(max)experimental and E(lambdamax)theoretical as a result.
However, E(lambdamax)exp > E(lambdamax)theo and I want to check whether
solvation effects could be expected to cause a red- or blue-shift. For this, I
need to know whether the b1g --> b3u transition at max is n-->pi* or
pi-->pi*.
How do I go about figuring that out from my calculations?