"Third‐body" collision parameters for hydrocarbons, alcohols, and hydroperoxides and an effective internal rotor approach for estimating them. Issue 6 (21st April 2020)

• Record Type: Journal Article
• Authors: Jasper, Ahren W.
• Is Part Of: International journal of chemical kinetics. Volume 52:Issue 6(2020)
• Page Start: 387
• Page End: 402
• Publication Date: 2020-04-21
• Subjects: classical trajectories -- Lennard‐Jones parameters -- third‐body collision efficiencies -- unimolecular kinetics -- automation; Chemical kinetics -- Periodicals; 541.394
• DOI: 10.1002/kin.21358
• Languages: English
• ISSNs: 0538-8066

Abstract

Abstract: Collision rate constants and third‐body collision efficiencies are calculated for more than 300 alkanes, alcohols, and hydroperoxides, for the bath gases He, Ar, H2, and N2, and from 300 to 2000 K. The data set includes highly branched species and species with as many as 16 nonhydrogen atoms N, and it is analyzed to develop strategies for estimating collision properties more generally. Simple analytic formulas describing the Lennard‐Jones collision parameters σ and ε are obtained for each of the three classes of systems as a function of N . Trends in the collision efficiency range parameter α = ⟨Δ Ed ⟩ are more complicated, and a method is developed and validated for estimating α based on the numbers and types of internal rotors and oxygen‐containing groups. Specifically, the approach maps the expected value of α for a branched alkane, alcohol, or hydroperoxide onto those for the corresponding normal (linear) series via an effective number of nonhydrogen atoms N eff . The prescription for N eff is based on counting internal rotor types and is shown to be insensitive to temperature and fairly insensitive to the identity of the bath gas. Together, these strategies allow for the ready estimation of the collision parameters σ, ε, and α so long as results for the associated linear series are available.