Department of Chemistry and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA.
J Chem Phys. 2012 Sep 14;137(10):104314. doi: 10.1063/1.4742968.
We calculate the standard state entropy, heat capacity, enthalpy, and Gibbs free energy for 13 radicals important for the combustion chemistry of biofuels. These thermochemical quantities are calculated from recently proposed methods for calculating partition functions of complex molecules by taking into account their multiple conformational structures and torsional anharmonicity. The radicals considered in this study are those obtained by hydrogen abstraction from 1-butanol, 2-methyl-1-propanol, and butanal. Electronic structure calculations for all conformers of the radicals were carried out using both density functional theory and explicitly correlated coupled cluster theory with quasipertubative inclusion of connected triple excitations. The heat capacity and entropy results are compared with sparsely available group additivity data, and trends in enthalpy and free energy as a function of radical center are discussed for the isomeric radicals.
我们计算了 13 种对生物燃料燃烧化学很重要的自由基的标准态熵、热容、焓和吉布斯自由能。这些热化学量是通过考虑复杂分子的多个构象结构和扭转非谐性，从最近提出的计算复杂分子配分函数的方法中计算得到的。本研究中考虑的自由基是从 1-丁醇、2-甲基-1-丙醇和丁醛中提取氢得到的自由基。使用密度泛函理论和显式相关耦合簇理论（准微扰包含连接三重激发）对所有自由基构象进行了电子结构计算。将热容和熵的结果与可用的基团加和数据进行了比较，并讨论了焓和自由能随自由基中心的变化趋势。
