title: Quantum dynamical investigation of the simplest Criegee intermediate CH2OO and its O-O photodissociation channels.
abstract: The singlet electronic potential energy surfaces for the simplest Criegee intermediate CH2OO are computed over a two-dimensional reduced subspace of coordinates, and utilized to simulate the photo-initiated dynamics on the S2 (B) state leading to dissociation on multiple coupled excited electronic states. The adiabatic electronic potentials are evaluated using dynamically weighted state-averaged complete active space self-consistent field theory. Quasi-diabatic states are constructed from the adiabatic states by maximizing the charge separation between the states. The dissociation dynamics are then simulated on the diabatically coupled excited electronic states. The B ← X electronic transition with large oscillator strength was used to initiate dynamics on the S2 (B) excited singlet state. Diabatic coupling of the B state with other dissociative singlet states results in about 5% of the population evolving to the lowest spin-allowed asymptote, generating H2CO (X (1)A1) and O ((1)D) fragments. The remaining ∼95% of the population remains on repulsive B state and dissociates to H2CO (a (3)A″) and O ((3)P) products associated with a higher asymptotic limit. Due to the dissociative nature of the B state, the simulated electronic absorption spectrum is found to be broad and devoid of any vibrational structure.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
authors.forename: Kousik
authors.initials: K
authors.lastname: Samanta
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Beames
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
authors.forename: Marsha I
authors.initials: MI
authors.lastname: Lester
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Subotnik
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D008958:Models, Molecular; D010126:Ozone / Q000737:chemistry*; D010782:Photolysis; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D000475:Alkenes; D010126:Ozone