Observation of the Wigner-Huntington transition to metallic hydrogen

Dias, Ranga; Silvera, Isaac F.

doi:10.1126/science.aal1579

Cited by 510 publications

(366 citation statements)

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“…Determination of the structure of phase III, which is relatively well established in the solid phase diagram, is still an object of debate. the condition at which semimetallic behavior has been observed [9], while the red squares are the condition where Wigner-Huntington transition has been reported [10]. The lines in the fluid phase reports recent claims of the observation of the liquid-liquid phase transition by different methods: static compression (green circles) [6], dynamic compression for deuterium (orange squares) [8], CEIMC simulations (blue circles hydrogen, blue squares deuterium) [21].…”

Section: Introductionmentioning

confidence: 96%

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Coupled electron-ion Monte Carlo simulation of hydrogen molecular crystals

Rillo

Morales

Ceperley

et al. 2017

The Journal of Chemical Physics

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We performed simulations for solid molecular hydrogen at high pressures (250GPa≤P≤500GPa) along two isotherms at T=200 K (phases III and VI) and at T=414 K (phase IV). At T=200K we considered likely candidates for phase III, the C2c and Cmca12 structures, while at T=414K in phase IV we studied the Pc48 structure. We employed both Coupled Electron-Ion Monte Carlo (CEIMC) and Path Integral Molecular Dynamics (PIMD) based on Density Functional Theory (DFT) using the vdW-DF approximation. The comparison between the two methods allows us to address the question of the accuracy of the xc approximation of DFT for thermal and quantum protons without recurring to perturbation theories. In general, we find that atomic and molecular fluctuations in PIMD are larger than in CEIMC which suggests that the potential energy surface from vdW-DF is less structured than the one from Quantum Monte Carlo. We find qualitatively different behaviors for systems prepared in the C2c structure for increasing pressure. Within PIMD the C2c structure is dynamically partially stable for P≤250GPa only: it retains the symmetry of the molecular centers but not the molecular orientation; at intermediate pressures it develops layered structures like Pbcn or Ibam and transforms to the metallic Cmca-4 structure at P≥450GPa. Instead, within CEIMC, the C2c structure is found to be dynamically stable at least up to 450GPa; at increasing pressure the molecular bond length increases and the nuclear correlation decreases. For the other two structures the two methods are in qualitative agreement although quantitative differences remain. We discuss various structural properties and the electrical conductivity. We find these structures become conducting around 350GPa but the metallic Drude-like behavior is reached only at around 500GPa, consistent with recent experimental claims.

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Section: Introductionmentioning

confidence: 96%

“…[9] though, no evidence of metallicity is found. More recently, Dias and Silvera [10] reported the observation of the Wigner-Huntington transition at 495 GPa and 5 K; this result has been much debated in the literature [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Coupled electron-ion Monte Carlo simulation of hydrogen molecular crystals

Rillo

Morales

Ceperley

et al. 2017

The Journal of Chemical Physics

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“…However, the reported metallization in Ref. [21] observed for atomic hydrogen based on reflectance of the sample is still highly debated [22][23][24]. What is certain is that the metallic phase involves metastable phases that are only accessible at high pressures and precise temperatures [20,[25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Interplay between structure and superconductivity: Metastable phases of phosphorus under pressure

Flores‐Livas

Sanna

Дроздов

et al. 2017

Phys. Rev. Materials

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Pressure-induced superconductivity and structural phase transitions in phosphorus (P) are studied by resistivity measurements under pressures up to 170 GPa and by fully ab initio crystal structure exploration and superconductivity calculations up to 350 GPa. Two distinct superconducting transition temperature (T C ) vs pressure (P ) trends at low pressure have been reported more than 30 years ago, and we are able to devise a consistent explanation founded on thermodynamically metastable phases of black phosphorus. Our experimental and theoretical results form a single, consistent picture which not only provides a clear understanding of elemental P under pressure but also sheds light on the longstanding and unsolved anomalous superconductivity trends. Moreover, at higher pressures we predict a similar scenario of multiple metastable structures which coexist beyond their thermodynamical stability range. We observe that all the metastable structures systematically exhibit larger transition temperatures than the ground-state structures, indicating that the exploration of metastable phases represents a promising route to design materials with improved superconducting properties.

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“…Notably, a transition to this structure was invoked to explain the onset of electrical conductivity observed at comparable pressures (270 GPa) [40]. More recently, evidence for a transition to a strongly reflecting phase of solid hydrogen at low temperatures and reportedly higher pressures was published (i.e., a different P-T domain) [50], but the lack of well-defined spectra, the use of coated diamonds, and uncertainty in the pressure estimation have raised questions about the results and interpretation [51].…”

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confidence: 98%