A theoretical benchmark study of the spectroscopic constants of the very heavy rare gas dimers.
A theoretical benchmark study of the spectroscopic constants of the very heavy rare gas dimers.
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DOI：
10.1039/c5cp01094b
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发表时间：
2015-04
期刊：
影响因子：
--
通讯作者：
Avijit Shee;S. Knecht;T. Saue
中科院分区：
文献类型：
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作者：
Avijit Shee;S. Knecht;T. Saue
本文报道了重稀有气体氡（Rn）和类氡（Uuo）的同素二聚体的光谱常数。一个计算协议，使用eXact 2-分量分子平均场哈密顿量已建立广泛的计算氙二聚体的基础上。我们发现，可靠的结果需要CCSD（T）计算外推的基础设置限制。在此极限下，平衡校正的结果比未校正的结果更接近实验得出的值。此外，在试图减少计算成本，同时保持非常高的精度，我们研究了距离分离密度泛函理论的性能。虽然我们观察到一个更有利的基组收敛和降低的重要性，连接的三元组的范围分离的方法相比，纯波函数理论，在实践中，我们必须采用相同的计算协议，以获得收敛的结果。在狄拉克-库仑水平上，我们发现从氡到类氡二聚体时，结合能几乎增加了四倍，但自旋-其他轨道相互作用的引入使最重二聚体的解离能降低了约40%。
Spectroscopic constants for the homonuclear dimers of the very heavy rare gases radon (Rn) and eka-radon (Uuo) are reported. A computational protocol using the eXact 2-Component molecular-mean field Hamiltonian has been established based on extensive calculations of the xenon dimer. We find that reliable results require CCSD(T) calculations at the extrapolated basis set limit. In this limit counterpoise corrected results are closer to experimentally derived values than uncorrected ones. Furthermore, in an attempt to reduce the computational cost while retaining very high accuracy, we studied the performance of range-separated density functional theory. Although we observe a somewhat more favorable basis set convergence and reduced importance of connected triples by range-separated methods compared to pure wave function theory, in practice we have to employ the same computational protocol for obtaining converged results. At the Dirac-Coulomb level we find an almost fourfold increase of binding energy when going from the radon to the eka-radon dimer, but the inclusion of spin-other orbit interaction reduces the dissociation energy of the heaviest dimer by about 40%.