Structures and relative stabilities of neutral acetonitrile clusters up to decamer have been investigated. We used the ABCluster code to thoroughly explore the potential energy surfaces (PESs) of the acetonitrile clusters and to generate initial geometries, which are further fully optimized at the MN15/6‐31++G(d,p) level of theory. Our exploration yielded several new local and global minima structures of the acetonitrile clusters. We located new global minimum structures of the acetonitrile pentamer to decamer. The results show that the PESs of the acetonitrile clusters are very flat, yielding several isoenergetic structures. Our investigations also revealed that the stability of the acetonitrile clusters is due both to CH⋯N and dipole–dipole interactions. Structures stabilized by the latter are found to be more stable than those stabilized by the former at low temperatures. Furthermore, we examined the effect of temperature on the stability of the structures of the acetonitrile clusters for temperatures in the range 20 to 400 K. We found that several structures contribute to the population of the clusters at high temperatures, and also that a significant contribution to the population comes from isomers that lie within 2.0 kcal/mol from the most stable one. In addition, we used the most stable structures to compute the binding energies of the acetonitrile clusters and to assess the performance of some DFT functionals (MN15, ωB97XD, PW6B95D3, and B2PLYP) in comparison with the MP2 method associated to the aug‐cc‐pVTZ basis set in calculating the binding energies. We found that the MN15 functional performs better than ωB97XD and PW6B95D3, and that MN15 is less sensitive to the basis set change. We also used an extrapolation scheme to calculate the binding energies of the acetonitrile clusters at the highly accurate W1BD, CBS‐QB3, and G4MP2 levels of theory. The resulting binding energies are recommended for future benchmarking of the acetonitrile clusters.

中文翻译：

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中性乙腈簇的结合能和异构体分布

研究了中性乙腈团簇直至十角的结构和相对稳定性。我们使用ABCluster代码彻底研究了乙腈簇的势能面（PES）并生成了初始几何形状，并在MN15 / 6-31 ++ G（d，p）的理论水平上对其进行了充分优化。我们的探索产生了乙腈簇的几个新的局部和全局最小结构。我们将乙腈五聚体的新的全球最小结构定位为十聚体。结果表明，乙腈簇的PES非常平坦，产生了几个同能结构。我们的研究还表明，乙腈簇的稳定性是由于CH⋯N和偶极-偶极相互作用引起的。发现在低温下由后者稳定的结构比由前者稳定的结构更稳定。此外，我们研究了温度对温度在20至400 K范围内的乙腈团簇结构稳定性的影响。我们发现，在高温下，有几种结构对团簇的分布有贡献，并且也做出了重要贡献相对于最稳定的异构体，其异构体在2.0 kcal / mol之内。此外，我们使用最稳定的结构来计算乙腈簇的结合能，并评估某些DFT功能的性能（MN15，我们研究了温度对20至400 K范围内温度对乙腈团簇结构稳定性的影响。我们发现，在高温下，有几种结构对团簇的分布有贡献，并且对人口来自最稳定的异构体在2.0 kcal / mol之内。此外，我们使用最稳定的结构来计算乙腈簇的结合能，并评估某些DFT功能的性能（MN15，我们研究了温度对20至400 K范围内温度对乙腈团簇结构稳定性的影响。我们发现，在高温下，有几种结构对团簇的分布有贡献，并且对人口来自最稳定的异构体在2.0 kcal / mol之内。此外，我们使用最稳定的结构来计算乙腈簇的结合能，并评估某些DFT功能的性能（MN15，ω B97XD，PW6B95D3和B2PLYP）与在计算结合能关联到AUG-CC-pVTZ基组的MP2方法比较。我们发现，比MN15功能进行更好的ω B97XD和PW6B95D3，那MN15是基础设置变化不太敏感。我们还使用外推方案在理论上非常精确的W1BD，CBS-QB3和G4MP2水平下计算乙腈簇的结合能。建议将产生的结合能用于将来乙腈簇的基准测试。