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arXiv 2110.06010astro-ph.GA
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星际含硫物质Binding Energies在结晶水冰模型上的从头计算

Ab initio Calculation of Binding Energies of Interstellar Sulphur-Containing Species on Crystalline Water Ice Models

Jessica Perrero, Albert Rimola, Marta Corno, Piero Ugliengo

备注：
Proceedings of the 21st International Conference on Computational Science and Its Applications, ICCSA 2021
发表信息：
LNCS 12953, 2021, 608
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摘要：

星际介质（ISM）中存在不同的环境，这取决于密度、温度和化学成分。其中，分子云通常被称为恒星的摇篮，是相对于空间化学多样性和复杂性的典范环境。事实上，在那里，无线电到远红外观测揭示了气相中存在几种分子，而近红外光谱检测到存在亚微米大小的尘埃颗粒，这些尘埃颗粒被以水为主的冰盖覆盖。气相物质与水冰表面之间的相互作用通过结合能（BE）来测量，结合能是天体化学建模中的一个关键参数。在这项工作中，一组含硫物种的水冰地幔的BE已被计算采用周期性从头计算方法使用的结晶表面模型。采用密度泛函理论（DFT）的B3 LYP-D3（BJ）方法对配合物的结构和能量进行了预测。在CCSD（T）水平上采用ONIOM方法对DFT边界元进行了精化，得到了很好的相关性。我们表明，几何优化与计算成本较低的HF-3c方法，其次是单点能量计算在DFT计算的BE是一个合适的成本-有效的配方，以达到与在全DFT级计算的BE值相同质量的BE值。最后，计算数据与现有文献数据进行了比较。

英文摘要：

There are different environments in the interstellar medium (ISM), depending on the density, temperature and chemical composition. Among them, molecular clouds, often referred to as the cradle of stars, are paradigmatic environments relative to the chemical diversity and complexity in space. Indeed, there, radio to far-infrared observations revealed the presence of several molecules in the gas phase, while near-infrared spectroscopy detected the existence of submicron sized dust grains covered by H2O -dominated ice mantles. The interaction between gas-phase species and the surfaces of water ices is measured by the binding energy (BE), a crucial parameter in astrochemical modelling. In this work, the BEs of a set of sulphur-containing species on water ice mantles have been computed by adopting a periodic ab initio approach using a crystalline surface model. The Density Functional Theory (DFT)-based B3LYP-D3(BJ) functional was used for the prediction of the structures and energetics. DFT BEs were refined by adopting an ONIOM-like procedure to estimate them at CCSD(T) level toward complete basis set extrapolation, in which a very good correlation between values has been found. Moreover, we show that geometry optimization with the computationally cheaper HF-3c method followed by single point energy calculations at DFT to compute the BEs is a suitable cost-effective recipe to arrive at BE values of the same quality as those computed at full DFT level. Finally, computed data were compared with the available literature data.

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