title: Enhancement of T(c) in the atomic phase of iodine-doped hydrogen at high pressures.
abstract: The high-pressure structures and superconductivity of iodine-doped hydrogen have been studied by ab initio calculations. Above 100 GPa, we discover a stable phase with Pnma symmetry in the H2I stoichiometry that consists of a monatomic iodine tube trapping hydrogen molecular units. Interestingly, H2 molecular units dissociate and form a novel atomic phase with R3̄m symmetry at 246 GPa. Further electron-phonon coupling calculations predict the critical temperature of superconductivity T(c) to be 3.8 K for the Pnma phase and 33 K for the R3̄m phase at 240 GPa. Significantly, the T(c) of the R3̄m phase is enhanced approximately 8 times that of the Pnma phase, which is mainly attributed to the reason that H2 molecules are broken exhibiting an atomic character in the R3̄m phase.
authors.affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, P. R. China. cuitian@jlu.edu.cn.
authors.forename: Defang
authors.initials: D
authors.lastname: Duan
authors.affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, P. R. China. cuitian@jlu.edu.cn.
authors.forename: Fubo
authors.initials: F
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, P. R. China. cuitian@jlu.edu.cn.
authors.forename: Yunxian
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authors.lastname: Liu
authors.affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, P. R. China. cuitian@jlu.edu.cn.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, P. R. China. cuitian@jlu.edu.cn.
authors.forename: Da
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authors.affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, P. R. China. cuitian@jlu.edu.cn.
authors.forename: Hongyu
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authors.lastname: Yu
authors.affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, P. R. China. cuitian@jlu.edu.cn.
authors.forename: Yanbin
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authors.lastname: Ma
authors.affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, P. R. China. cuitian@jlu.edu.cn.
authors.forename: Bingbing
authors.initials: B
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, 130012, P. R. China. cuitian@jlu.edu.cn.
authors.forename: Tian
authors.initials: T
authors.lastname: Cui