Cuong Ngo Tuan, Mai Nguyen Thi, Tung Nguyen Thanh, Lan Ngo Thi, Duong Long Van, Nguyen Minh Tho, Tam Nguyen Minh
Faculty of Chemistry, Center for Computational Science, Hanoi National University of Education Hanoi Vietnam.
Institute of Materials Science, Graduate University of Science and Technology, Vietnam Academy of Science and Technology 18 Hoang Quoc Hanoi Vietnam.
RSC Adv. 2021 Dec 16;11(63):40072-40084. doi: 10.1039/d1ra06994b. eCollection 2021 Dec 13.
Geometrical and electronic structures of the 13-atom clusters Al Sc with + = 13, as well as their thermodynamic stabilities were investigated using DFT calculations. Both anionic and neutral isomers of Al Sc were found to retain an icosahedral shape of both Al and Sc systems in which an Al atom occupies the endohedral central position of the icosahedral cage, irrespective of the number of Al atoms present. Such a phenomenon occurs to maximize the number of stronger Al-Al and Sc-Al bonds instead of the weaker Sc-Sc bonds. NBO analyses were applied to examine their electron configurations and rationalize the large number of open shells and thereby high multiplicities of the mixed clusters having more than three Sc atoms. The SOMOs are the molecular orbitals belonged to the irreducible representations of the symmetry point group of the clusters studied, rather than to the cluster electron shells. Evaluation of the average binding energies showed that the thermodynamic stability of Al Sc clusters is insignificantly altered as the number goes from 0 to 7 and then steadily decreases when attains the 7-13 range. Increase of the Sc atom number also reduces the electron affinities of the binary Al Sc clusters, and thus they gradually lose the superhalogen characteristics with respect to the pure Al.
利用密度泛函理论（DFT）计算研究了总原子数(N = 13)的(Al_{N}Sc_{13 - N})（(N = 0)到(13)）十三原子团簇的几何结构和电子结构，以及它们的热力学稳定性。发现(Al_{N}Sc_{13 - N})的阴离子和中性异构体都保持了(Al)和(Sc)体系的二十面体形状，其中一个(Al)原子占据二十面体笼的内面中心位置，而与存在的(Al)原子数量无关。出现这种现象是为了使更强的(Al - Al)和(Sc - Al)键的数量最大化，而不是较弱的(Sc - Sc)键。应用自然键轨道（NBO）分析来研究它们的电子构型，并解释大量的开壳层以及因此具有多于三个(Sc)原子的混合团簇的高多重性。单占据分子轨道（SOMO）属于所研究团簇对称点群的不可约表示的分子轨道，而不是团簇电子壳层。平均结合能的评估表明，随着(N)从(0)增加到(7)，(Al_{N}Sc_{13 - N})团簇的热力学稳定性变化不明显，而当(N)达到(7 - 13)范围时则稳步下降。(Sc)原子数的增加也降低了二元(Al_{N}Sc_{13 - N})团簇的电子亲和能，因此相对于纯(Al)团簇，它们逐渐失去超卤素特性。
