Accurate Predictions of Electron Binding Energies of Dipole-Bound Anions via Quantum Monte Carlo Methods
Accurate Predictions of Electron Binding Energies of Dipole-Bound Anions via Quantum Monte Carlo Methods
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DOI：
10.1021/acs.jpclett.8b02733
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发表时间：
2018-11-01
影响因子：
5.7
通讯作者：
Rubenstein, Brenda M.
中科院分区：
文献类型：
--
作者：
Hao, Hongxia;Shee, James;Rubenstein, Brenda M.
具有足够大的偶极矩的中性分子可以将电子束缚在扩散的非价轨道上，其中大部分电荷密度远离原子核，形成所谓的偶极束缚阴离子。由于长程相关效应在过量电子的结合中起着重要的作用，并且总体结合能通常仅在10 s-100 s波数的量级上，因此预测性地建模偶极结合阴离子仍然是一个挑战。在这里，我们证明了量子蒙特卡罗方法可以准确地表征分子偶极束缚阴离子与近阈值的偶极矩。我们还表明，相关采样辅助场量子蒙特卡罗是特别适合解决的中性和阴离子物种之间的能量差异。这些结果揭示了量子蒙特卡罗方法的基本局限性，并为使用它们研究弱结合物种铺平了道路，这些物种太大，无法使用传统的电子结构方法进行建模。
Neutral molecules with sufficiently large dipole moments can bind electrons in diffuse nonvalence orbitals with most of their charge density far from the nuclei, forming so-called dipole-bound anions. Because longrange correlation effects play an important role in the binding of an excess electron and overall binding energies are often only on the order of 10s-100s of wave numbers, predictively modeling dipole-bound anions remains a challenge. Here, we demonstrate that quantum Monte Carlo methods can accurately characterize molecular dipole-bound anions with near-threshold dipole moments. We also show that correlated sampling Auxiliary Field Quantum Monte Carlo is particularly well-suited for resolving the fine energy differences between the neutral and anionic species. These results shed light on the fundamental limitations of quantum Monte Carlo methods and pave the way toward using them for the study of weakly bound species that are too large to model using traditional electron structure methods.