Group Additivity for Thermochemical Property Estimation of Lignin Monomers on Pt(111)

Conversion of biomass
has received considerable attention, but
theoretical investigation is challenging due to the large computational
burden. In this contribution, we explore group additivity for computing
the thermochemistry of lignin monomers, and by extension to single-ring
aromatic hydrocarbons, on Pt(111). We find that the previous framework
developed for open-chain molecules and furanics is inadequate for
lignin monomers due to conjugation. Using quantum theory of atoms
in molecules (QTAIM), we find that the type of binding of the adsorbate
atoms with the surface sites, for example, σ, σσ,
or σπ, has an important impact on the conjugation of bonds
in adsorbates. We introduce two new models that account for the type
of binding of the central atom and its nearest neighbors, namely,
a conjugation-based and a site-based scheme, which result in significant
improvement. A total of 591 density functional theory data points
were regressed; cross-validation of the site-based scheme reveals
that mean absolute errors are 2.81 kcal/mol in ΔHf,298, 1.07 cal/(mol K) in ΔS298, and 0.25 cal/(mol K) in Cp,300. The slightly simpler conjugation-based model, which does not resolve
the binding type of all nearest neighbors, also performs well.

生物质转化已获得广泛关注，但受限于庞大的计算负荷，理论研究颇具挑战。本工作探究了用于计算铂(111)晶面上木质素单体热化学性质的基团加和法，并推广至单环芳烃体系。研究发现，此前针对开链分子与呋喃类化合物开发的理论框架，因共轭效应的存在，无法适用于木质素单体。借助分子中的原子量子理论（Quantum Theory of Atoms in Molecules, QTAIM），我们发现吸附质原子与表面位点的结合类型（如σ、σσ或σπ），对吸附质内化学键的共轭效应具有显著影响。我们提出了两种新模型，分别为基于共轭效应的方案与基于位点的方案，用于考量中心原子及其近邻原子的结合类型，二者均实现了性能的显著提升。本研究共回归拟合了591个密度泛函理论（density functional theory, DFT）数据点；对基于位点方案的交叉验证结果显示，其平均绝对误差分别为：298K下的标准生成焓ΔHf,298为2.81 kcal/mol，298K下的熵ΔS298为1.07 cal/(mol·K)，300K下的定压热容Cp,300为0.25 cal/(mol·K)。无需明确区分所有近邻原子结合类型的简化版基于共轭效应的模型，同样表现优异。