Critical temperature of metallic hydrogen at a pressure of 500 GPa

Kudryashov, Nikolay A.; Кутуков, А. А.; Mazur, E. A.

doi:10.1134/s0021364016190061

Cited by 21 publications

(9 citation statements)

References 7 publications

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“…Later, McMahon and Ceperley predicted a Tc above room temperature for atomic MH with Tc increasing to several hundred K with increasing pressure [22]. Borinaga et al [23] predicted a Tc of 300 K at 500 GPa; Kudryashov, Kutukov, and Mazur predict Tc =217 K [24]; Yan, Gong, and Liu predict a Tc of 291 K [25]; Verma et al, Tc above RT [26]. Clearly there is a great deal of variation in the theoretical estimates and Tc needs to be determined experimentally.…”

Section: Superconductivity In the Hydrogensmentioning

confidence: 99%

Phases of the hydrogen isotopes under pressure: metallic hydrogen

Silvera

Dias

2021

Advances in Physics: X

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Hydrogen is the simplest molecule in nature. One of the key problems and challenges in condensed matter physics is to understand the phases, properties, and structure of hydrogen as a function of pressure and temperature. Over 80 years ago Wigner and Huntington predicted that if solid molecular hydrogen was sufficiently compressed, it would transform to an atomic metal. Later, a second pathway emerged; it was predicted that if heated to high temperatures under pressure it would transform to liquid atomic hydrogen; this form of metallic hydrogen makes up ~90% of the planet Jupiter. The prediction of high temperature superconductivity of solid atomic metallic hydrogen stimulated the experimental community to produce this material . For decades hydrogen defied the experimental efforts to transform it. Using diamond anvil cells, metallic hydrogen has recently been produced at a pressure of ~5 million atmospheres, significantly greater than the pressure at the center of the earth. Liquid atomic metallic hydrogen has been produced at temperatures of a few thousand degrees Kelvin in diamond anvil cells, as well as in dynamic experiments. We review the seemingly simple, but actually complex properties of this quantum solid and metal and the decades of development and progress to achieve this important fundamental result.

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Section: Superconductivity In the Hydrogensmentioning

confidence: 99%

Phases of the hydrogen isotopes under pressure: metallic hydrogen

Silvera

Dias

2021

Advances in Physics: X

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“…Theoretical analysis of various crystalline phases of solid hydrogen was carried out in refs. [66][67][68][69][70][71], where the equation of state was calculated and an estimate is obtained of the possibility of the existence of metallic hydrogen in the region of low pressures. Various cubic symmetric structures of both molecular and atomic hydrogen in the region of possible metallization are investigated.…”

Section: Transition Of Solid Hydrogen To the Conducting Statementioning

confidence: 99%

Plasma phase transition (by the fiftieth anniversary of the prediction)

Norman

Saitov

2019

Contributions to Plasma Physics

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At first, we present a brief review of the problem. Then, we consider plasma phase transition (PPT) as a mechanism of the first order fluid-fluid phase transition in warm dense hydrogen. The pros and cons are analysed. The properties of warm dense hydrogen are investigated by ab initio methods of molecular dynamics using the density functional theory. Strong ionization during the fluid-fluid phase transition in warm dense hydrogen makes this transition close to the prediction of the PPT. Finally, we present differences in the real phase transition from the prediction 1968-1969. Structures are observed with inter-proton separations that are equal to the distances between protons in the H + 2 and H + 3 ions. The transition is not only ionization, but also structural. An analysis of the phase transition counterpart in solid hydrogen under high pressure allows us to reveal partially the character of the new structure. The ionized phase includes complex cluster ions. Van der Waals loops are of abnormal inverted form. KEYWORDSdense hydrogen, density functional theory, pair correlation function, plasma phase transition INTRODUCTION: THREE PREDICTIONS OF 1968-1970The plasma phase transition (PPT) was predicted by Norman and Starostin [1] in 1968. The strong overlapping in the density of the equilibrium branch of one phase with a metastable branch of another phase was predicted in ref.[2]. The third prediction was a triple point on the melting curve. [3,4] Nature of the transitionThe hypothesis of PPT is advanced in ref.[1] by analogy with the van der Waals equation of state, where a first-order phase transition arises as a result of the competition between the long-range weak attraction and short-range strong repulsion between neutral particles, and temperature. In plasmas, due to the polarization of spatial charge distribution, the average Coulomb interaction energy of particles is negative and, therefore, has a general character of the long-range weak effective Coulomb attraction. This interaction is introduced into the expression for the free energy of plasma in the form of Debye-Hückel correction.where Γ = (4 /3) 1/3 e 2 n e 1/3 /kT is the Coulomb non-ideality parameter, T is the temperature, e is the elementary charge, k is the Boltzmann's constant, n e is the charge number density. In the region Γ > 1, the system becomes thermodynamically unstable. To stabilize the system of charged particles, a short-range effective quantum repulsion between free electrons and ions is taken into account in ref.[1], along with the Coulomb interaction. The localization of free charges at close distances leads to an increase

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“…Other theoretical works involve among others recent diffusion quantum Monte-Carlo simulations [8,38] and advanced DFT methods [39,40]. Both methods predict the metallization for pressures in the range 400−500GP a in the three-dimensional case.…”

Section: B Relation To Other Workmentioning

confidence: 99%

Metallization of solid molecular hydrogen in two dimensions: Mott-Hubbard-type transition

2017

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We analyze the pressure-induced metal-insulator transition in a two-dimensional vertical stack of H2 molecules in (x-y) plane, and show that it represents a striking example of the Mott-Hubbardtype transition. Our combined exact diagonalization approach, formulated and solved in the second quantization formalism, includes also simultaneous ab initio readjustment of the single-particle wave functions, contained in the model microscopic parameters. The system is studied as a function of applied side force (generalized pressure), both in the H2-molecular and H-quasiatomic states. Extended Hubbard model is taken at the start, together with longer-range electron-electron interactions incorporated into the scheme. The stacked molecular plane transforms discontinuously into a (quasi)atomic state under the applied force via a two-step transition: the first between molecular insulating phases and the second from the molecular to the quasiatomic metallic phase. No quasiatomic insulating phase occurs. All the transitions are accompanied by an abrupt changes of the bond length and the intermolecular distance (lattice parameter), as well as by discontinuous changes of the principal electronic properties, which are characteristic of the Mott-Hubbard transition here associated with the jumps of the predetermined equilibrium lattice parameter and the effective bond length. The phase transition can be interpreted in terms of the solid hydrogen metallization under pressure exerted by e.g., the substrate covered with a monomolecular H2 film of the vertically stacked molecules. Both the Mott and Hubbard criteria at the insulator to metal transition are discussed. I. MOTIVATIONHydrogen is the first and the simplest of elements in the Periodic Table, with an elementary structure of the energy levels. Also, the H 2 molecule represents the testing ground of quantum-mechanical methods [1,2]. This elementary nature of the atomic or molecular energy levels transforms into an involved manifold of states and available energies as exemplified by the abundance of their condensed liquid and solid phases [3,4]. The resultant phase diagram is complex, and the catalogue of observed phases -especially of the solid ones -steadily increases [3,5]. The lack of clarity concerning their crystal structure in many cases is intimately connected with an incomplete insight into their electronic properties. However, it has been unclear until very recently [6] whether the solid-hydrogen atomic and metallic phase may indeed exist. Nonetheless, the detailed nature of this transition from an insulating molecular phase to the (quasi-)metallic atomic state, is still under debate [7,8], starting from the historic paper by Wigner and Huntington [9]. Once confirmed [10], the recent work [6] would represent a decisive step in achieving our understanding of the metallization of molecular hydrogen both experimentally and * andrzej.biborski@agh.edu.pl † kadzielawa@th.if.uj.edu.pl ‡ jozef.spalek@uj.edu.pl theoretically. The fundamental question is whether this transition...

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Critical temperature of metallic hydrogen at a pressure of 500 GPa

Cited by 21 publications

References 7 publications

Phases of the hydrogen isotopes under pressure: metallic hydrogen

Phases of the hydrogen isotopes under pressure: metallic hydrogen

Plasma phase transition (by the fiftieth anniversary of the prediction)

Metallization of solid molecular hydrogen in two dimensions: Mott-Hubbard-type transition

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