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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Borazine and Benzene Homo- and Heterodimers
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Borazine and Benzene Homo- and Heterodimers

机译：硼嗪和苯均二聚体和异二聚体

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摘要

The homodimers of benzene and borazine as well as a heterodimer consisting of one benzene (bz) and one borazine (bor) molecule are investigated using MP2, SCS-MP2, and CCSD(T) theories in conjunction with basis sets of up to quadruple- quality. Dimer geometries were completely optimized using the resolution of the identity approximation of MP2 with a QZVPP basis set and characterized by computation of harmonic vibrational frequencies using triple- basis sets. While significant higher order correlation effects beyond MP2 are important for the benzene dimer, these are very small for the borazine dimer and intermediate for the heterodimer. The spin-component scaling (SCS) correction of MP2 produces binding energies for the borazine dimer that are too low but yields very good agreement with CCSD(T) for the heterodimer. The decrease in the intermolecular distance in the sandwich (S) configurations from bz2 via bz-bor to bor2 is accompanied by an increased binding energy and a change from second-order stationary points to a minimum for bor2. The T isomer is less stable than the S configuration for bor2, but it is preferred over the S and a parallel-displaced (PD) arrangement in the heterodimer. The following order of stability is obtained for the minima at the extrapolated CCSD(T) level: T(bz-bor) > S(bor2) > PD(bz-bor) > PD(bor2) > T(bor2) > PD(bz2). The most stable isomer at all levels of theory, T(bz-bor), features a NH interaction.
机译：使用MP2，SCS-MP2和CCSD（T）理论并结合了多达四倍的基数，研究了苯和硼嗪的同二聚体以及由一个苯（bz）和一个硼嗪（bor）分子组成的异二聚体质量。使用具有QZVPP基集的MP2的恒等近似的分辨率，可以完全优化二聚体的几何形状，并使用三基集计算谐波振动频率来表征二聚体的几何形状。尽管超过MP2的显着的高阶相关效应对苯二聚体很重要，但对于硼嗪二聚体和异二聚体的中间体而言，这些效应很小。 MP2的自旋组分定标（SCS）校正产生的硼嗪二聚体结合能太低，但与CCSD（T）的异二聚体产生非常好的一致性。从bz2经由bz-bor到bor2的三明治（S）构型的分子间距离的减小伴随着结合能的增加以及bor2从二阶固定点到最小值的变化。 T异构体的稳定性不如bor2的S构型，但优于异二聚体中的S和平行位移（PD）排列。对于外推CCSD（T）级别的最小值，获得以下稳定性顺序：T（bz-bor）> S（bor2）> PD（bz-bor）> PD（bor2）> T（bor2）> PD（ bz2）。在所有理论水平上，最稳定的异构体T（bz-bor）具有NH相互作用。

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