The stability of different stoichiometric HnBr (n=1-7) compounds under pressure are extensively studied using density functional theory calculations. Five new energetically stable stoichiometries of H2Br, H3Br, H4Br, H5Br, and H7Br were uncovered at high pressure. The results show that HBr is stable below 64 GPa, then decomposes into new compound H2Br and Br2 molecular crystal. For H2Br and H3Br compounds, they were found to become stable above 30 GPa and 8 GPa, respectively. In addition, we accidentally discovered the triangular H3+ species in H5Br compounds at 100 GPa. Further electron-phonon coupling calculations predicted that hydrogen-rich H2Br and H4Br compounds are superconductors with critical temperature of superconductivity Tc of 12.1 K and 2.4 K at 240 GPa, respectively.
@article{arxiv.1504.01196,
title = {Decomposition of solid hydrogen bromide at high pressure},
author = {Defang Duan and Fubo Tian and Xiaoli Huang and Da Li and Hongyu Yu and Yunxian Liu and Yanbin Ma and Bingbing Liu and Tian Cui},
journal= {arXiv preprint arXiv:1504.01196},
year = {2015}
}