title: Imaginary vibrational modes in polycyclic aromatic hydrocarbons: a challenging test for the hardness profiles.
abstract: In a very recent article (J. Am. Chem. Soc. 2006, 128, 9342-9343) Moran et al. found that electron-correlated methodologies using popular Pople basis sets lead to spurious nonplanar polycyclic aromatic hydrocarbon (PAH) equilibrium structures. Furthermore, some of the present authors have shown that the hardness profiles along a reaction path can be a useful tool to find spurious stationary points in the potential energy surface. Herein, we test the performance of the hardness profiles to detect shortcomings in energy profiles for the challenging case of nonplanar PAHs. The results obtained show that in 41 of the 42 imaginary vibrational modes studied, the hardness profiles indicate the wrong number and type of the potential energy surface stationary points.
authors.affiliation: Eenheid Algemene Chemie, Faculteit Wetenschappen, Vrije Universiteit Brussel (VUB), Pleinlaan 2, Brussels, Belgium. mtorrent@vub.ac.be
authors.forename: Miquel
authors.initials: M
authors.lastname: Torrent-Sucarrat
authors.forename: Paul
authors.initials: P
authors.lastname: Geerlings
authors.forename: Josep M
authors.initials: JM
authors.lastname: Luis
mesh_terms: D000838:Anions / Q000737:chemistry; D003198:Computer Simulation; D006244:Hardness; D015394:Molecular Structure; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D014732:Vibration
chemical_list: D000838:Anions; D011084:Polycyclic Aromatic Hydrocarbons