论文标题

星际与水冰上相关的含S含物物种的结合能:量子机械研究

Binding Energies of Interstellar Relevant S-bearing Species on Water Ice Mantles: A Quantum Mechanical Investigation

论文作者

Perrero, J., Enrique-Romero, J., Ferrero, S., Ceccarelli, C., Podio, L., Codella, C., Rimola, A., Ugliengo, P.

论文摘要

结合能(BES)是确定星体化学建模的最重要参数之一,因为它们控制着物种是在气相中停留还是在晶粒表面上冻结。目前众所周知,在星际培养基的较密集和较冷的区域中,硫在气相中严重耗尽。有人建议将其锁定在谷物冰冷的地幔中。但是,这是主要的硫载体仍然是辩论的问题。这项工作旨在在两个经过验证的水冰结构模型,质子订购的晶体(010)表面和无定形水冰表面上确定17种含硫磺物种的BES。我们采用了密度功能理论(DFT)基于基于的方法(杂种B3LYP-D3(BJ)和混合元GGGA M06-2X功能)来预测吸附复合物的结构和能量学。伦敦的分散相互作用对于由于存在高极化硫元素而进行的准确估计至关重要。虽然在结晶模型上,吸附限制在具有单个值BES的结合位点非常有限的结合位点,而在无定形模型上,预测了几种吸附结构,从而给每个物种分布。除少数情况外,实验数据和其他计算数据都与我们计算出的为值一致。最终讨论的最终讨论提供了在原行星磁盘中相对于同一物种的雪线的有用

Binding energies (BEs) are one of the most important parameters for astrochemical modeling determining, because they govern whether a species stays in the gas-phase or is frozen on the grain surfaces. It is currently known that, in the denser and colder regions of the interstellar medium, sulphur is severely depleted in the gas phase. It has been suggested that it may be locked into the grain icy mantles. However, which are the main sulphur carriers is still a matter of debate. This work aims at establishing accurate BEs of 17 sulphur-containing species on two validated water ice structural models, the proton-ordered crystalline (010) surface and an amorphous water ice surface. We adopted Density Functional Theory (DFT)-based methods (the hybrid B3LYP-D3(BJ) and the hybrid meta-GGA M06-2X functionals) to predict structures and energetics of the adsorption complexes. London's dispersion interactions are shown to be crucial for an accurate estimate of the BEs due to the presence of the high polarizable sulphur element. While on the crystalline model the adsorption is restricted to a very limited number of binding sites with single valued BEs, on the amorphous model several adsorption structures are predicted, giving a BE distribution for each species. With the exception of few cases, both experimental and other computational data are in agreement with our calculated BE values. A final discussion on how useful the computed BEs are with respect to the snow lines of the same species in protoplanetary disks is provided

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