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“Third‐body” collision parameters for hydrocarbons, alcohols, and hydroperoxides and an effective internal rotor approach for estimating them
International Journal of Chemical Kinetics ( IF 1.5 ) Pub Date : 2020-04-21 , DOI: 10.1002/kin.21358
Ahren W. Jasper 1
Affiliation  

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 = ⟨ΔEd⟩ 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 Neff. The prescription for Neff 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.

中文翻译:

碳氢化合物,醇和氢过氧化物的“第三体”碰撞参数以及估算它们的有效内部转子方法

对于浴气体He,Ar,H 2和N 2以及300至2000 K,计算了300多种烷烃,醇和氢过氧化物的碰撞速率常数和第三者碰撞效率。数据集包括高度分支的种类和具有多达16个非氢原子N的种类,并对其进行分析以开发出更一般地估计碰撞性质的策略。对于三类系统,分别获得了描述Lennard-Jones碰撞参数σε的简单解析公式,作为N的函数。在碰撞效率范围参数趋势α  =⟨Δ È d⟩更复杂,因此开发并验证了一种基于内部转子和含氧基团的数量和类型来估算α的方法。具体而言,该方法通过有效数量的非氢原子N eff将支链烷烃,醇或氢过氧化物的α期望值映射到对应的正态(线性)序列的期望值。N eff的规定是基于对内部转子类型的计数,并且显示出对温度不敏感并且对浴气的特性相当不敏感。总之,这些策略允许对碰撞参数σεα进行随时估计。 只要相关联的线性序列的结果可用。
更新日期:2020-04-21
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