Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA.
Science. 2009 Dec 4;326(5958):1382-4. doi: 10.1126/science.1181017.
The beryllium dimer has puzzled chemists for roughly 80 years on account of its unexpectedly strong bonding interaction between two nominally closed-shell atoms. Recent spectroscopic measurements characterized the molecule's ground electronic state with sufficient resolution to distinguish 11 vibrational levels; the possibility that a twelfth level lay just below the dissociation threshold remained unresolved. Here we present a potential function, based on ab initio calculations at the full configuration interaction level, that definitively supports the presence of this twelfth vibrational state. "Morphed" versions of this potential, fitted to experimental data, closely reproduce the observed spectra to within 0.1 cm(-1), bolstering the strength of the assignment.
铍二聚体因其两个名义上的满壳原子之间存在出乎意料的强键相互作用而令化学家困惑了大约 80 年。最近的光谱测量以足够的分辨率来描述分子的基态电子态，足以区分 11 个振动能级；第十二个能级是否位于离解阈值以下仍未得到解决。在这里，我们提出了一个基于完全组态相互作用水平的从头算计算的势能函数，该函数明确支持存在第十二个振动能级。这个势能的“变形”版本拟合实验数据，在 0.1 cm(-1) 以内非常好地再现了观察到的光谱，从而增强了分配的强度。
