Published in Henry Rzepa's Blog
Author Henry Rzepa
![](http://www.ch.ic.ac.uk/rzepa/blog/wp-content/uploads/2010/06/trefoil-kekule.jpg)
A conjugated, (apparently) aromatic molecular trefoil might be expected to have some unusual, if not extreme properties. Here some of these are explored. The first is the vibrational spectrum. With 144 atoms for this molecule, it has 426 vibrational modes, but one is highlighted below. This is the mode that moves the atoms in accord with the Kekulé resonance. If real, this mode resists such alternation.