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arXiv · 1007.0161

Properties of Vacancy Formation in He-4 hcp Crystals at Zero Temperature and Fixed Pressure

Y. Lutsyshyn·C. Cazorla·G. E. Astrakharchik·J. Boronat
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Abstract

Equation of state of He-4 hcp crystals with vacancies is determined at zero temperature using the diffusion Monte Carlo technique, an exact ground state zero-temperature method. This allows us to extract the formation enthalpy and isobaric formation energy of a single vacancy in otherwise perfect helium solid. Results were obtained for pressures up to 160 bar. The isobaric formation energy is found to reach a minimum near 57 bar where it is equal to $10.5\pm 1.2$ K. At the same pressure, the vacancy formation volume exhibits a maximum and reaches the volume of the unit cell. This pressure coincides with the pressure interval over which a peak in the supersolid fraction of He-4 was observed in a recent experiment.

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Y. Lutsyshyn, C. Cazorla, G. E. Astrakharchik, J. Boronat. 2010-07-01. Properties of Vacancy Formation in He-4 hcp Crystals at Zero Temperature and Fixed Pressure. https://doi.org/10.1103/physrevb.82.180506

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