Hi,
I compared 1,4-pentadiene and 1,3-pentadiene using UFF geometry optimization. 1,3 gives energy 2.8351307 and 1.4 gives lower energy of 2.7028027. I would expect 1,3-isomer to give lower energy due to double bonds conjugation… Any comments ?
2 replies
The UFF force field (or any current force field for that matter) does not have any interaction term for delocalization.
To get accurate relative energies for delocalization effects, you’ll need some level of QM method.
Hello.
Did you fix your prooblem with delocalization&conjugation with some other software?
As far as I know there is no force field method that exists that handles delocalization. I would say that if you need to work on specific interactions that occur from delocalization, then you need to use a more advanced QM package, something like ORCA.
There may come a time when Avogadro will have something like GFN2-XTB, which may be able to handle something like that with relative ease, but until then it won’t be accounted for here.