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<p>The computational chemistry capsule exercise on calculating UV
transitions is one of my favorite. As you have seen, oftentimes
to get useful information out of Gaussian you have to do several
things. That is the case here as well. On Friday I showed you a
way to get the minimum energy to break the O-O bond in hydrogen
peroxide. An actual electronic transition that went to a
dissociative well would in all likelihood take even more energy.
What about the amount of energy required just to cause an
electronic excitation. Remember, there are lots of different ways
to electronically excite a molecule and each different excitation
results in different excited state potential curves.<br>
</p>
In these systems we focus on just the HOMO and LUMO. As directed,
do a minimization, then look at the MO's in the output file. RECORD
THE NUMBER OF THE HOMO AND LUMO as well and if they are <img
style="vertical-align: middle"
src="cid:part1.25125678.B0F526EA@mercer.edu" alt="$\sigma$">, <img
style="vertical-align: middle"
src="cid:part2.DA2F0B8F.B499F05A@mercer.edu" alt="$\sigma^*$">, <img
style="vertical-align: middle"
src="cid:part3.15C522FD.A0AAD182@mercer.edu" alt="$\pi$">, <img
style="vertical-align: middle"
src="cid:part4.968B5F0C.ACBFAEF9@mercer.edu" alt="$\pi^*$">. You
must record the number of the orbital because that is the only
reference you will have to find it in the next step.<br>
<br>
Using your optimized geometry do the ZINDO calculation and follow
the directions as indicated.<br>
<br>
<br>
<pre class="moz-signature" cols="72">--
Andrew J. Pounds, Ph.D. (<a class="moz-txt-link-abbreviated" href="mailto:pounds_aj@mercer.edu">pounds_aj@mercer.edu</a>)
Professor of Chemistry and Computer Science
Mercer University, Macon, GA 31207 (478) 301-5627
<a class="moz-txt-link-freetext" href="http://faculty.mercer.edu/pounds_aj">http://faculty.mercer.edu/pounds_aj</a>
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