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Structure evolution of chromium-doped boron clusters: toward the formation of endohedral boron cages
- Shao, Xuecheng, Qu, Xin, Liu, Siyu, Yang, Lihua, Yang, Jinghai, Liu, Xiaohui, Zhong, Xin, Sun, Shuai, Vaitheeswaran, G., Lv, Jian
- RSC advances 2019 v.9 no.5 pp. 2870-2876
- boron, chemical structure, chromium, geometry
- The electron-deficient nature of boron endows isolated boron clusters with a variety of interesting structural and bonding properties that can be further enriched through metal doping. In the current work, we report the structural and electronic properties of a series of chromium-doped boron clusters. The global minimum structures for CrBₙ clusters with an even number of n ranging from 8 to 22 are proposed through extensive first-principles swarm-intelligence structure searches. Half-sandwich structures are found to be preferred for CrB₈, CrB₁₀, CrB₁₂ and CrB₁₄ clusters and to transform to a drum-like structure at CrB₁₆ cluster. Endohedral cage structures with the Cr atom located at the center are energetically most favorable for CrB₂₀ and CrB₂₂ clusters. Notably, the endohedral CrB₂₀ cage has a high symmetry of D₂d and a large HOMO–LUMO gap of 4.38 eV, whose stability is attributed to geometric fit and formation of an 18-electron closed-shell configuration. The current results advance our understanding of the structure and bonding of metal-doped boron clusters.