title: The photochemistry of formaldehyde: internal conversion and molecular dissociation in a single step?
abstract: A novel, nonadiabatic reaction path for H2 + CO molecular dissociation of formaldehyde via an extended S1/S0 conical intersection seam has been mapped out using the CAS-SCF method with a full valence active space (10 electrons, 9 orbitals). Two conical intersection geometries have been optimized, CsCoIn, a saddle point in the intersection space, and C1CoIn, which is the lowest-energy crossing point. A minimum-energy path connecting these points along a seam has also been characterized. In addition to the conventional and "roaming-atom" mechanisms--where internal conversion takes place before ground-state dissociation--we suggest that a strictly nonadiabatic mechanism can operate, where internal conversion and dissociation take place in concert.
authors.forename: Marta
authors.initials: M
authors.lastname: Araujo
authors.forename: Benjamin
authors.initials: B
authors.lastname: Lasorne
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bearpark
authors.forename: Michael A
authors.initials: MA
authors.lastname: Robb