Database of Small Molecule Thermochemistry for Combustion

High-accuracy ab initio thermochemistry is presented
for 219 small molecules relevant in combustion chemistry, including
many radical, biradical, and triplet species. These values are critical
for accurate kinetic modeling. The RQCISD­(T)/cc-PV∞QZ//B3LYP/6-311++G­(d,p)
method was used to compute the electronic energies. A bond additivity
correction for this method has been developed to remove systematic
errors in the enthalpy calculations, using the Active Thermochemical
Tables as reference values. On the basis of comparison with the benchmark
data, the 3σ uncertainty in the standard-state heat of formation
is 0.9 kcal/mol, or within chemical accuracy. An uncertainty analysis
is presented for the entropy and heat capacity. In many cases, the
present values are the most accurate and comprehensive numbers available.
The present work is compared to several published databases. In some
cases, there are large discrepancies and errors in published databases;
the present work helps to resolve these problems.

本研究报道了针对219个与燃烧化学相关的小分子的高精度从头算（ab initio）热化学数据，其中包含诸多自由基、双自由基及三重态物种。此类数据对于精准动力学建模具有关键意义。本研究采用RQCISD(T)/cc-PV∞QZ//B3LYP/6-311++G(d,p)方法计算电子能量，并以主动热化学表（Active Thermochemical Tables）作为参考值，开发了适用于该方法的键加和性校正方案以消除焓计算中的系统误差。通过与基准数据比对，标准态生成焓的3σ不确定度为0.9 kcal/mol，达到化学精度要求。本研究同时针对熵与热容开展了不确定度分析。在多数情况下，本研究给出的数据为当前可获得的最精准且最全面的热化学数据。本研究将所得结果与多个已发表的数据库进行了比对，部分已发表数据库存在较大偏差与错误，本研究可为解决此类问题提供有效支撑。