Complex Low Energy Tetrahedral Polymorphs of Group IV Elements from First Principles

He, Chaoyu; Shi, Xizhi; Clark, Stewart J.; Li, Jin; Pickard, Chris J.; Ouyang, Tao; Zhang, Chunxiao; Tang, Chao; Zhong, Jianxin

Abstract

The energy landscape of carbon is exceedingly complex, hosting diverse and important metastable phases, including diamond, fullerenes, nanotubes, and graphene. Searching for structures, especially those with large unit cells, in this landscape is challenging. Here we use a combined stochastic search strategy employing two algorithms (ab initio random structure search and random sampling strategy combined with space group and graph theory) to apply connectivity constraints to unit cells containing up to 100 carbon atoms. We uncover three low energy carbon polymorphs ( P b a m − 32 , P 6 / m m m , and I ¯ 4 3 d ) with new topologies, containing 32, 36, and 94 atoms in their primitive cells, respectively. Their energies relative to diamond are 96, 131, and 112     meV / atom , respectively, which suggests potential metastability. These three carbon allotropes are mechanically and dynamically stable, insulating carbon crystals with superhard mechanical properties. The I ¯ 4 3 d structure possesses a direct band gap of 7.25 eV, which is the widest gap in the carbon allotrope family. Silicon, germanium, and tin versions of P b a m − 32 , P 6 / m m m , and I ¯ 4 3 d also show energetic, dynamical, and mechanical stability. The computed electronic properties show that they are potential materials for semiconductor and photovoltaic applications.

Citation

He, C., Shi, X., Clark, S., Li, J., Pickard, C. J., Ouyang, T., …Zhong, J. (2018). Complex Low Energy Tetrahedral Polymorphs of Group IV Elements from First Principles. Physical Review Letters, 121(17), Article 175701. https://doi.org/10.1103/physrevlett.121.175701

• Journal Article Type: Article
• Acceptance Date: Oct 10, 2018
• Online Publication Date: Oct 26, 2018
• Publication Date: Oct 26, 2018
• Deposit Date: Oct 29, 2018
• Publicly Available Date: Oct 30, 2018
• Journal: Physical Review Letters
• Print ISSN: 0031-9007
• Electronic ISSN: 1079-7114
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 121
• Issue: 17
• Article Number: 175701
• DOI: https://doi.org/10.1103/physrevlett.121.175701
• Public URL: https://durham-repository.worktribe.com/output/1314612
• Related Public URLs: https://arxiv.org/pdf/1810.04896.pdf