Ultrahigh-pressure isostructural electronic transitions in hydrogen

Ji, Cheng; Li, Bing; Liu, Wenjun; Smith, Jesse S.; Majumdar, Arnab; Luo, Wei; Ahuja, Rajeev; Shu, Jinfu; Wang, Junyue; Sinogeikin, Stanislav V.; Meng, Yue; Prakapenka, Vitali B.; Greenberg, Eran; Xu, Ruqing; Huang, Xianrong; Yang, Wenge; Shen, Guoyin; Mao, Wendy L.; Mao, Ho‐kwang

doi:10.1038/s41586-019-1565-9

Cited by 99 publications

(90 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The emergence of these minima with increasing pressure gives rise to corresponding distortions of the wave functions with an increased probability density at ∼55 • to the a-b plane seen in the ground and first excited states. This tendency of the wave function to flatten is consistent with AIMD [29,30], Monte Carlo [31], and experiment [32] in phase I, and opposite to theories that predict the molecule pointing preferentially out of plane [33]. Figure 4 shows the variation of the energy levels with applied potential, with coloring indicating the mixing of spherical harmonics.…”

Section: Resultssupporting

confidence: 70%

Raman signal from a hindered hydrogen rotor

et al. 2020

View full text Add to dashboard Cite

Section: Resultssupporting

confidence: 70%

Raman signal from a hindered hydrogen rotor

et al. 2020

View full text Add to dashboard Cite

“…The turnover also means the liquid has higher compressibility, but how this comes about remains unexplained. X-ray studies at low temperature traversing Phase I-II-III do not show any convincing structural changes, in part because it has proven impossible to get sufficient resolution to determine the molecular orientation 8,9 .…”

mentioning

confidence: 99%

Understanding high pressure molecular hydrogen with a hierarchical machine-learned potential

2020

View full text Add to dashboard Cite

The hydrogen phase diagram has several unusual features which are well reproduced by density functional calculations. Unfortunately, these calculations do not provide good physical insights into why those features occur. Here, we present a fast interatomic potential, which reproduces the molecular hydrogen phases: orientationally disordered Phase I; broken-symmetry Phase II and reentrant melt curve. The H2 vibrational frequency drops at high pressure because of increased coupling between neighbouring molecules, not bond weakening. Liquid H2 is denser than coexisting close-packed solid at high pressure because the favored molecular orientation switches from quadrupole-energy-minimizing to steric-repulsion-minimizing. The latter allows molecules to get closer together, without the atoms getting closer, but cannot be achieved within in a close-packed layer due to frustration. A similar effect causes negative thermal expansion. At high pressure, rotation is hindered in Phase I, such that it cannot be regarded as a molecular rotor phase.

show abstract

“…On page 558, Ji et al 2 report experiments that probe this structure at unprecedented pressures, revealing a hexagonal close-packed arrangement of molecules.…”

Section: B a R To M E U M O N S E R R At And C H R I S J P I C K A R Dmentioning

confidence: 99%

“…■ Figure 1 | Structure of hydrogen under extreme pressure. Ji et al 2 demonstrate that the molecules in three high-pressure solid phases of hydrogen adopt a hexagonal close-packed structure. The drawing is a snapshot of where the two constantly moving protons in each molecule might be located.…”

Section: X-rays Glimpse Solid Hydrogen's Structurementioning

confidence: 99%