Two-dimensional molecular para-hydrogen and ortho-deuterium at zero temperature

Abstract

We study molecular para-hydrogen (p-${\mathrm{H}}_2$) and ortho-deuterium (o-${\mathrm{D}}_2$) in two dimensions and in the limit of zero temperature by means of the diffusion Monte Carlo method. We report energetic and structural properties of both systems like the total and kinetic energy per particle, radial pair distribution function, and Lindemann's ratio in the low pressure regime. By comparing the total energy per particle as a function of the density in liquid and solid p-${\mathrm{H}}_2$, we show that molecular para-hydrogen, and also ortho-deuterium, remain solid at zero temperature. Interestingly, we assess the quality of three different symmetrized trial wave functions, based on the Nosanow-Jastrow model, in the p-${\mathrm{H}}_2$ solid film at the variational level. In particular, we analyze a new type of symmetrized trial wave function which has been used very recently to describe solid ${}^4$He and found that also characterizes hydrogen satisfactorily. With this wave function, we show that the one-body density matrix ${\varrho }_1(r)$ of solid p-${\mathrm{H}}_2$ possesses off-diagonal long range order, with a condensate fraction that increases sizably in the negative pressure regime.

11 pages, 9 figures

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Cited by in corpus (11)

• Simulation and understanding of quantum crystals
• Superfluidity of metastable bulk glass para-hydrogen at low temperature
• Phase diagram of H2 adsorbed on graphene
• First-Principles Modeling of Quantum Nuclear Effects and Atomic Interactions in Solid 4He at High Pressure
• The elastic constants of solid 4He under pressure: a diffusion Monte Carlo study
• Ground-state properties and superfluidity of two- and quasi two-dimensional solid 4He
• Possible superfluidity of molecular hydrogen in a two-dimensional crystal phase of sodium
• Second layer of H2 and D2 adsorbed on graphene
• Supersolidity in the second layer of $para$-H${}_2$ adsorbed on graphite
• Neural Network Interaction Potentials for para-Hydrogen with Flexible Molecules
• Candidate theories to explain the anomalous spectroscopic signatures of atomic H in molecular H${}_2$ crystals