A classical trajectory study of the photodissociation of T1 acetaldehyde: The transition from impulsive to statistical dynamics

Simple item page
dc.contributor.authorThompson KC
dc.contributor.authorKable SH
dc.contributor.authorJordan MJT
dc.contributor.authorCrittenden, Deborah
dc.date.accessioned2023-03-23T01:06:04Z
dc.date.available2023-03-23T01:06:04Z
dc.date.issued2006en
dc.date.updated2023-02-13T02:50:18Z
dc.description.abstractPrevious experimental and theoretical studies of the radical dissociation channel of T1 acetaldehyde show conflicting behavior in the HCO and CH3 product distributions. To resolve these conflicts, a full-dimensional potential-energy surface for the dissociation of CH3CHO into HCO and CH3 fragments over the barrier on the T1 surface is developed based on RO-CCSDT/cc-pVTZDZ ab initio calculations. 20 000 classical trajectories are calculated on this surface at each of five initial excess energies, spanning the excitation energies used in previous experimental studies, and translational, vibrational, and rotational distributions of the radical products are determined. For excess energies near the dissociation threshold, both the HCO and CH3 products are vibrationally cold; there is a small amount of HCO rotational excitation and little CH3 rotational excitation, and the reaction energy is partitioned dominantly 90% at threshold into relative translational motion. Close to threshold the HCO and CH3 rotational distributions are symmetrically shaped, resembling a Gaussian function, in agreement with observed experimental HCO rotational distributions. As the excess energy increases the calculated HCO and CH3 rotational distributions are observed to change from a Gaussian shape at threshold to one more resembling a Boltzmann distribution, a behavior also seen by various experimental groups. Thus the distribution of energy in these rotational degrees of freedom is observed to change from nonstatistical to apparently statistical, as excess energy increases. As the energy above threshold increases all the internal and external degrees of freedom are observed to gain population at a similar rate, broadly consistent with equipartitioning of the available energy at the transition state. These observations generally support the practice of separating the reaction dynamics into two reservoirs: an impulsive reservoir, fed by the exit channel dynamics, and a statistical reservoir, supported by the random distribution of excess energy above the barrier. The HCO rotation, however, is favored by approximately a factor of 3 over the statistical prediction. Thus, at sufficiently high excess energies, although the HCO rotational distribution may be considered statistical, the partitioning of energy into HCO rotation is not.en
dc.identifier.citationThompson KC, Crittenden DL, Kable SH, Jordan MJT (2006). A classical trajectory study of the photodissociation of T1 acetaldehyde: The transition from impulsive to statistical dynamics. The Journal of Chemical Physics. 124(4). 44302-.en
dc.identifier.doihttp://doi.org/10.1063/1.2139672
dc.identifier.issn0021-9606
dc.identifier.issn1089-7690
dc.identifier.urihttps://hdl.handle.net/10092/105286
dc.languageeng
dc.language.isoenen
dc.publisherAIP Publishingen
dc.rightsAll rights reserved unless otherwise stateden
dc.rights.urihttp://hdl.handle.net/10092/17651en
dc.subject.anzsrc02 Physical Sciencesen
dc.subject.anzsrc03 Chemical Sciencesen
dc.subject.anzsrc09 Engineeringen
dc.subject.anzsrcFields of Research::34 - Chemical sciences::3407 - Theoretical and computational chemistry::340701 - Computational chemistryen
dc.subject.anzsrcFields of Research::34 - Chemical sciences::3406 - Physical chemistry::340607 - Reaction kinetics and dynamicsen
dc.titleA classical trajectory study of the photodissociation of T1 acetaldehyde: The transition from impulsive to statistical dynamicsen
dc.typeJournal Articleen
uc.collegeFaculty of Science
uc.departmentSchool of Physical & Chemical Sciences
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
JCP_2006_124_044302.pdf
Size:
272.21 KB
Format:
Adobe Portable Document Format
Description:
Published version
Download
Collections
Science: Journal Articles