Free surface of superfluid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">He</mml:mi><mml:mprescripts /><mml:none /><mml:mn>4</mml:mn></mml:mmultiscripts></mml:math>at zero temperature

This work expands recent investigations in the field of spin-polarized tritium ͑T↓͒ clusters. We report the results for the ground-state energy and structural properties of large T↓ clusters consisting of up to 320 atoms. All calculations have been performed with variational and diffusion Monte Carlo methods, using an accurate ab initio interatomic potential. Our results for N Յ 40 are in good agreement with results obtained by other groups. Using a liquid-drop expression for the energy per particle, we estimate the liquid equilibrium density, which is in good agreement with our recently obtained results for bulk T↓. In addition, the calculations of the energy for large clusters have allowed for an estimation of the surface tension. From the mean-square radius of the drop, determined using unbiased estimators, we determine the dependence of the radii on the size of the cluster and extract the unit radius of the T↓ liquid.

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“…In order to determine the central density as precisely as possible, we have tried to fit the density profile with the function used in Ref. 27,…”

Section: Resultsmentioning

confidence: 99%

Quantum Monte Carlo study of large spin-polarized tritium clusters

Bešlić

Markić

Boronat

2009

The Journal of Chemical Physics

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“…34,38 We recall that the surface thickness of liquid helium is a quantity rather difficult to determine experimental and theoretically, 39 and the dispersion of the values assigned to it is large. [34][35][36][37][38][39][40][41] Only recently have the mentioned values ͑ϳ6 -6.5 Å for 4 He and ϳ7.5 Å for 3 He͒ emerged as likely accurate determinations of the surface thickness of the liquid helium free surface.…”

Section: A Liquid 4 Hementioning

confidence: 99%

Electron bubbles in liquid helium: Density functional calculations of infrared absorption spectra

et al. 2006

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Within density functional theory, we have calculated the energy of the transitions from the ground state to the first two excited states in the electron bubbles in liquid helium at pressures from zero to about the solidification pressure. For 4 He at low temperatures, our results are in very good agreement with infrared absorption experiments. Above a temperature of ϳ2 K, we overestimate the energy of the 1s-1p transition. We attribute this to the break down of the Franck-Condon principle due to the presence of helium vapor inside the bubble. Our results indicate that the 1s-2p transition energies are sensitive not only to the size of the electron bubble, but also to its surface thickness. We also present results for the infrared transitions in the case of liquid 3 He, for which we lack experimental data.

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“…With these conditions we guarantee an accurate model for the free surface of 4 He, as shown in Ref. 28. On top of one of the slab surfaces we introduce a variable number N H of H↓ atoms that form a thin layer of surface densities σ = N H /A.…”

Section: Resultsmentioning

confidence: 99%

“…19 The use of accurate He-He potentials and ground-state quantum Monte Carlo methods proved to be able to reproduce experimental data directly related to the surface, like the surface tension and the surface width. 28 In the present work, we rely on a similar methodology to the one previously used in the study of the free 4 He surface 28 in order to microscopically characterize the ground-state of H↓ adsorbed on its surface. Our study is complemented by a purely twodimensional simulation of H↓ in order to establish the degree of two-dimensionality of the adsorbed film.…”

Section: Introductionmentioning

confidence: 99%

Spin-polarized hydrogen adsorbed on the surface of superfluid 4He

Marı́n

Markić

Boronat

2013

The Journal of Chemical Physics

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The experimental realization of a thin layer of spin-polarized hydrogen H↓ adsorbed on top of the surface of superfluid 4 He provides one of the best examples of a stable, nearly two-dimensional (2D) quantum Bose gas. We report a theoretical study of this system using quantum Monte Carlo methods in the limit of zero temperature. Using the full Hamiltonian of the system, composed of a superfluid 4 He slab and the adsorbed H↓ layer, we calculate the main properties of its ground state using accurate models for the pair interatomic potentials. Comparing the results for the layer with the ones obtained for a strictly 2D setup, we analyze the departure from the 2D character when the density increases. Only when the coverage is rather small the use of a purely 2D model is justified. The condensate fraction of the layer is significantly larger than in 2D at the same surface density, being as large as 60% at the largest coverage studied. © 2013 AIP Publishing LLC.

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Free surface of superfluidHe4at zero temperature

Cited by 17 publications

References 50 publications

Quantum Monte Carlo study of large spin-polarized tritium clusters

Quantum Monte Carlo study of large spin-polarized tritium clusters

Electron bubbles in liquid helium: Density functional calculations of infrared absorption spectra

Spin-polarized hydrogen adsorbed on the surface of superfluid 4He

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