Insights into photodissociation dynamics of acetaldehyde from ab initio calculations and molecular dynamics simulations

Journal Article · Fri Aug 07 00:00:00 EDT 2009 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3196176· OSTI ID:21559758

Shilu, Chen ^[1]; Weihai, Fang ^[1]

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1. College of Chemistry, Beijing Normal University, Beijing 100875 (China)

In the present paper we report a theoretical study on mechanistic photodissociation of acetaldehyde (CH{sub 3}CHO). Stationary structures for H{sub 2} and CO eliminations in the ground state (S{sub 0}) have been optimized with density functional theory method, which is followed by the intrinsic reaction coordinate and ab initio molecular dynamics calculations to confirm the elimination mechanism. Equilibrium geometries, transition states, and intersection structures for the C-C and C-H dissociations in excited states were determined by the complete-active-space self-consistent field (CASSCF) method. Based on the CASSCF optimized structures, the potential energy profiles for the dissociations were refined by performing the single-point calculations using the multireference configuration interaction method. Upon the low-energy irradiation of CH{sub 3}CHO (265 nm<{lambda}<318 nm), the T{sub 1} C-C bond fission following intersystem crossing from the S{sub 1} state is the predominant channel and the minor channel, the ground-state elimination to CH{sub 4}+CO after internal conversion (IC) from S{sub 1} to S{sub 0}, could not be excluded. With the photon energy increasing, another pathway of IC, achieved via an S{sub 1}/S{sub 0} intersection point resulting from the S{sub 1} C-C bond fission, becomes accessible and increases the yield of CH{sub 4}+CO.

• OSTI ID: 21559758
• Journal Information: Journal of Chemical Physics, Vol. 131, Issue 5; Other Information: DOI: 10.1063/1.3196176; (c) 2009 American Institute of Physics; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACETALDEHYDE
CARBON MONOXIDE
CHEMICAL BONDS
CONFIGURATION INTERACTION
DENSITY FUNCTIONAL METHOD
DISSOCIATION
EQUILIBRIUM
EXCITED STATES
FISSION
HYDROGEN
INTERNAL CONVERSION
IRRADIATION
METHANE
MOLECULAR DYNAMICS METHOD
PHOTOLYSIS
PHOTONS
POTENTIAL ENERGY
REACTION KINETICS
SELF-CONSISTENT FIELD
SIMULATION
ALDEHYDES
ALKANES
BOSONS
CALCULATION METHODS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CONVERSION
DECAY
DECOMPOSITION
ELEMENTARY PARTICLES
ELEMENTS
ENERGY
ENERGY LEVELS
HYDROCARBONS
KINETICS
MASSLESS PARTICLES
NONMETALS
NUCLEAR DECAY
NUCLEAR REACTIONS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
VARIATIONAL METHODS