How to measure stability
Dear netters,
I have a question which should be of considerable interest for
computational chemists. The question is: How do I measure computationally
the stability of organic molecules?
I study some molecules which presumably have not yet been prepared. And I
would like to know if these molecules have a chance to exist. What I did
so far is the most simple and obvios method: I compared the absolute
electronic energy with the same quantity on a known and more or less
stable isomer. But from the results I got I think that this is only a
crude approximation on a "measure" of stability and reactivity.
What I didn't examine yet but could be quite sensible (I think) is doing
a CI or MCSCF calculation and looking at the energy gap between the
frontier orbitals and comparing it to known isomers.
Another way could be an examination of the computed IR-spectrum. Are
there very low frequencies (shallow dips in the potential engergy
surface) which could lead to "new" molecules?
Is there a way to determine "centers of reactivity" ?
Has someone any ideas about this topic?
I will summarize it to the list, if I get any responses ;)
Bye, Thorsten
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| Thorsten Koch |
| Institut fuer Physikalische Chemie II der Universitaet zu Koeln |
| Luxemburger Str. 116, 50939 Koeln, Germany |
| acp37 "at@at" rrz.uni-koeln.de |
| Tel. +49 [0]221 470 4816 |
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