title: That Little Extra Kick: Nonadiabatic Effects in Acetaldehyde Photodissociation.
abstract: The effect of nonadiabatic transitions on branching ratios, kinetic and internal energy distribution of fragments, and reaction mechanisms observed in acetaldehyde photodissociation is investigated by nonadiabatic molecular dynamics (NAMD) simulations using time-dependent hybrid density functional theory and Tully surface hopping. Homolytic bond breaking is approximately captured by allowing spin symmetry to break. The NAMD simulations reveal that nonadiabatic transitions selectively enhance the kinetic energy of certain internal degrees of freedom within approximately 50 fs. Branching ratios from NAMD and conventional "hot" Born-Oppenheimer molecular dynamics (BOMD) are similar and qualitatively agree with experiment. However, as opposed to the BOMD simulations, NAMD captures the high-energy tail of the experimental kinetic energy distribution. The extra "kick" of the nuclei in the direction of the nonadiabatic coupling vector results from nonadiabatic transitions close to conical intersections. From a mechanistic perspective, the nonadiabatic effects favor asynchronous over synchronous fragmentation and tend to suppress roaming.
authors.affiliation: Department of Chemistry, University of California, Irvine , 1102 Natural Sciences II, Irvine, California 92697-2025, United States.
authors.forename: Jordan C
authors.initials: JC
authors.lastname: Vincent
authors.affiliation: Department of Chemistry, University of California, Irvine , 1102 Natural Sciences II, Irvine, California 92697-2025, United States.
authors.forename: Mikko
authors.initials: M
authors.lastname: Muuronen
authors.affiliation: Department of Chemistry, University of California, Irvine , 1102 Natural Sciences II, Irvine, California 92697-2025, United States.
authors.forename: Kirk C
authors.initials: KC
authors.lastname: Pearce
authors.affiliation: Department of Chemistry, University of California, Irvine , 1102 Natural Sciences II, Irvine, California 92697-2025, United States.
authors.forename: Luke N
authors.initials: LN
authors.lastname: Mohanam
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Long Beach , 1250 Bellflower Boulevard, Long Beach, California 90840-9507, United States.
authors.forename: Enrico
authors.initials: E
authors.lastname: Tapavicza
authors.affiliation: Department of Chemistry, University of California, Irvine , 1102 Natural Sciences II, Irvine, California 92697-2025, United States.
authors.forename: Filipp
authors.initials: F
authors.lastname: Furche