Hydrogen in porous Vycor glass

Schindler, M.; Dertinger, A.; Kondo, Yasushi; Pobell, F.

doi:10.1103/physrevb.53.11451

Cited by 60 publications

(40 citation statements)

References 40 publications

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“…Following this line of thinking many experimental and theoretical studies have focused on the characterization and analysis of p-H 2 films adsorbed on different substrates. [5][6][7][8] For instance, two-dimensional hydrogen has been observed to freeze at temperatures around 5 K when placed onto an exfoliated graphite plate. 9 Also, it has been experimentally shown that small para-hydrogen clusters immersed in 4 He droplets exhibit superfluidlike behavior.…”

Section: Introductionmentioning

confidence: 99%

Possible superfluidity of molecular hydrogen in a two-dimensional crystal phase of sodium

Cazorla

Boronat²

2013

Phys. Rev. B

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We theoretically investigate the ground-state properties of a molecular para-hydrogen (p-H 2 ) film in which crystallization is energetically frustrated by embedding sodium (Na) atoms periodically distributed in a triangular lattice. In order to fully deal with the quantum nature of p-H 2 molecules, we employ the diffusion Monte Carlo method and realistic semiempirical pairwise potentials describing the interactions between H 2 -H 2 and Na-H 2 species. In particular, we calculate the energetic, structural, and superfluid properties of two-dimensional Na-H 2 systems within a narrow density interval around equilibrium at zero temperature. In contrast to previous computational studies considering other alkali metal species such as rubidium and potassium, we find that the p-H 2 ground state is a liquid with a significantly large superfluid fraction of ρ s /ρ = 0.29(2). The appearance of p-H 2 superfluid response is due to the fact that the interactions between Na atoms and H 2 molecules are less attractive than between H 2 molecules. This induces a considerable reduction of the hydrogen density which favors the stabilization of the liquid phase.

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Section: Introductionmentioning

confidence: 99%

Possible superfluidity of molecular hydrogen in a two-dimensional crystal phase of sodium

Cazorla

Boronat²

2013

Phys. Rev. B

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“…This is due the depth of the attractive well of the potential between two Hydrogen molecules, significantly greater than that between two Helium atoms. Several, attempts have been made 3,4,5,6 to supercool bulk liquid p-H 2 , but the search for SF (in the bulk) has so far not met with success.…”

Section: Introductionmentioning

confidence: 99%

Melting of ap−H2monolayer on a lithium substrate

Boninsegni

2004

Phys. Rev. B

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Adsorption of p-H2 films on Alkali metals substrates at low temperature is studied theoretically by means of Path Integral Monte Carlo simulations. Realistic potentials are utilized to model the interaction between two p-H2 molecules, as well as between a p-H2 molecule and the substrate, assumed smooth. Results show that adsorption of p-H2 on a Lithium substrate, the most attractive among the Alkali, occurs through completion of successive solid adlayers. Each layer has a twodimensional density θe ≈ 0.070Å −2 . A solid p-H2 monolayer displays a higher degree of confinement, in the direction perpendicular to the substrate, than a monolayer Helium film, and has a melting temperature of about 6.5 K. The other Alkali substrates are not attractive enough to be wetted by H2 at low temperature. No evidence of a possible superfluid phase of p-H2 is seen in these systems.

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“…Several attempts have been made [10]- [13] to supercool bulk liquid p-H 2 , but the search for a SF phase has so far not met with success. Confinement and reduction of dimensionality are widely regarded as plausible avenues to the stabilization of a liquid phase of p-H 2 at temperatures sufficiently low, such that a SF transition may be observed.…”

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confidence: 99%

Theoretical study of H₂in a two-dimensional crystalline matrix

Boninsegni

2005

New J. Phys.

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Ground-state properties and superfluidity of two-and quasi-two-dimensional solid4He C Cazorla, G E Astrakharchik, J Casulleras et al. Abstract. We have carried out extensive path integral Monte Carlo simulations of two-dimensional para-hydrogen (p-H 2 ) embedded in a crystalline matrix of alkali atoms. Our results show that, at low temperatures ( 5 K), the thermodynamically stable phase of p-H 2 is a solid, commensurate with the underlying lattice. A nonzero superfluid signal for p-H 2 is observed in simulated systems of very small size (e.g. 13 molecules); however, results for systems of larger sizes are altogether consistent with absence of superfluidity in the thermodynamic limit. Contents

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Hydrogen in porous Vycor glass

Cited by 60 publications

References 40 publications

Possible superfluidity of molecular hydrogen in a two-dimensional crystal phase of sodium

Possible superfluidity of molecular hydrogen in a two-dimensional crystal phase of sodium

Melting of ap−H2monolayer on a lithium substrate

Theoretical study of H₂in a two-dimensional crystalline matrix

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Hydrogen in porous Vycor glass

Cited by 60 publications

References 40 publications

Possible superfluidity of molecular hydrogen in a two-dimensional crystal phase of sodium

Possible superfluidity of molecular hydrogen in a two-dimensional crystal phase of sodium

Melting of ap−H2monolayer on a lithium substrate

Theoretical study of H2in a two-dimensional crystalline matrix

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Theoretical study of H₂in a two-dimensional crystalline matrix