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首页> 外文期刊>Chemistry: A European journal >On the existence of Cu~I pairs in ZSM-5-A computational study
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On the existence of Cu~I pairs in ZSM-5-A computational study

机译：关于ZSM-5-A计算研究中Cu〜I对的存在

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The siting and coordination of Cu~I pairs in zeolite ZMS-5 have been studied by means of a combined quantum mechanics/interatomic potential function technique (QM-Pot). It couples a density functional theory (DFT) description employing a hybrid functional (B3LYP) for copper ions, including their local environment, with a DFT-parameterized shell model ion-pair potential for the periodic ZSM-5 structure. A missing Cu~I-Cu~I interaction potential term in the force field has been parameterized on the basis of DFT results. Several distinct coordination sites for Cu~I pairs have been identified within the ZSM-5 framework. These have been classified as open, nest, open-nest, and cage pairs, owing to the shape of their local environment in the crystal. A nest-shaped, bridged eight-membered ring constitutes the most probable site for the existence of Cu~I ion pairs. It is energetically favored over all isolated Cu~I sites. The excitation and emission energies for the single-triplet transition of the Cu~I pairs have been studied. Earlier assignment of an emission based at 520 nm to Cu~I pairs by others is not supported by our computed results.
机译：结合量子力学/原子间势函数技术（QM-Pot）研究了ZMS-5分子筛中Cu〜I对的配位和配位。它结合了密度泛函理论（DFT）的描述，该描述对铜离子（包括其局部环境）采用了杂合官能团（B3LYP），并为周期性ZSM-5结构提供了DFT参数化的壳模型离子对电势。根据DFT结果，参数化了力场中缺失的Cu〜I〜Cu〜I相互作用势项。在ZSM-5框架内已经确定了Cu〜I对的几个不同的配位位点。由于它们在晶体中的局部环境形状，它们被分为开放，巢，开放巢和网箱对。巢状，桥连的八元环构成了Cu〜I离子对存在的最可能的位置。在所有孤立的Cu〜I位点上，它都受到能量的大力支持。研究了Cu〜I对单三重跃迁的激发和发射能。我们的计算结果不支持其他人更早地将基于520 nm的发射分配给Cu_I对。

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