Properties of vacancy formation in hcp 4He crystals at zero temperature and fixed pressure

被引:16
作者
Lutsyshyn, Y. [1 ]
Cazorla, C. [2 ]
Astrakharchik, G. E. [1 ]
Boronat, J. [1 ]
机构
[1] Univ Politecn Cataluna, Dept Fis & Engn Nucl, E-08034 Barcelona, Spain
[2] UCL, Dept Chem, London WC1H 0AJ, England
来源
PHYSICAL REVIEW B | 2010年 / 82卷 / 18期
关键词
MONTE-CARLO; THERMAL VACANCIES; HELIUM;
D O I
10.1103/PhysRevB.82.180506
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
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 are 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 +/- 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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页数:4
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