A new method for calculating low‐pressure strong‐collision rate constants of dissociation and recombination reactions was proposed. The method is based on determining the density of states of the internal degrees of freedom of the reactant molecule by applying the inverse Laplace transform to the respective partition function, which, in turn, is calculated from the thermodynamic properties in the form of NASA polynomials. The proposed model is universal in the sense that the required NASA polynomials can be calculated using molecular properties obtained by various methods, both theoretical and experimental or a combination thereof. In the present study, the NASA polynomials were taken from the available databases or calculated from thermodynamic functions, either tabulated or determined by statistical mechanics in the rigid‐rotor harmonic‐oscillator approximation, with a simple anharmonicity correction introduced when necessary. In addition, a model for calculating the rotational factor is developed and tested. It is based on determination of the centrifugal barrier as a function of the dissociating bond length at a given rotational energy through calculating the principal moments of inertia of the molecule at each step of elongation of the bond. The proposed approach is exemplified for the dissociation of the H₂O, HO₂, and H₂O₂ molecules and the corresponding reverse reactions. A comparison with the available experimental data made it possible to estimate the weak‐collision efficiency. At high temperatures, for all the reactions studied, the weak collision efficiency appears to be quite reasonable, whereas, at low temperatures, the situation is unsatisfactory, except perhaps for H₂O dissociation. Given that the energy threshold E₀ of dissociation reactions is typically well known, the calculated and measured dissociation rate constants are represented and handled in terms of the preexponential factor A(T) in the expression k(T) = A(T)exp(−E₀/RT). A new formula for fitting A(T) was proposed: log A(T) = a + b(1000/T) + c(1000/T)^p, which turned out to be a good approximation for the preexponential factors of not only the rate constants but also the equilibrium constants.

中文翻译：

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根据NASA热力学多项式计算强碰撞解离速率常数

提出了一种计算离解和复合反应低压强碰撞速率常数的新方法。该方法基于通过将拉普拉斯逆变换应用于相应的分配函数来确定反应物分子内部自由度的状态密度，该反拉普拉斯变换又是根据NASA多项式形式的热力学性质计算的。在可以使用通过各种方法获得的分子特性（理论和实验方法或其组合）获得的NASA多项式进行计算的意义上，建议的模型具有通用性。在本研究中，NASA多项式取自可用的数据库或根据热力学函数计算得出，在刚性转子谐波振荡器近似中以表格或统计力学方法确定，并在必要时引入简单的非谐波校正。另外，开发并测试了用于计算旋转系数的模型。它基于在给定旋转能量下通过计算键延伸每个步骤中分子的主惯性矩来确定作为分离键长度的函数的离心势垒。所提出的方法以H的解离为例 它是基于在给定旋转能量下，通过计算键延伸每个步骤中分子的主惯性矩来确定作为分离键长度的函数的离心势垒的。所提出的方法以H的解离为例 它基于在给定旋转能量下通过计算键延伸每个步骤中分子的主惯性矩来确定作为分离键长度的函数的离心势垒。所提出的方法以H的解离为例₂ O，HO ₂和H ₂ O ₂分子以及相应的逆反应。与可用的实验数据进行比较可以估算弱碰撞效率。在高温下，对于所有研究的反应，较弱的碰撞效率似乎是相当合理的，而在低温下，情况可能并不令人满意，除了可能发生H ₂ O分解。假定解离反应的能量阈值E ₀通常是众所周知的，则根据表达式k中的指数前因子A（T）表示和处理计算和测量的解离速率常数。（T）＝  A（T）exp（-E ₀ / RT）。提出了一个新的拟合A（T）的公式：log A（T）=  a + b（1000 / T）+ c（1000 / T）^p，可以很好地近似于指数因子。速率常数，还有平衡常数。