Abstract
In this work, the isotherm and energy distribution atT= 304 K of dense helium are studied by molecular dynamic (MD) simulations with exp-6 potential r* = 2.967 3 Á (the position of the weil minimum) and ɛ/k B = 10.8 K (ɛ is the well-depth andk B is the Boltzmann constant) given by Peter et al., and different values of stiffness parameter α. The optimized value of α= 12.7 is deduced that can describe the atomic interactions for dense helium satisfactorily. This optimized α in exp-6 potential is used to conduct MD simulations of two isotherms of dense helium atT= 300 K andT = 298 K. The calculations are in good agreement with the experimental. We further employed this method to investigate the equation-of-state and structure of dense helium at higher temperatures and found that when the density remained 1.6 g/cm3, the second peak of the radial distribution function would disappear in the temperature range from 2 000 to 3 040 K, demonstrating that a solid-liquid transition or decrystallization had occurred.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Younger, S. M., Harrison, K., Sugiyama, G., Many-electron effects transport processes in dense helium, Phys. Rev. A, 1989,40(9): 5256.
Janzen, A. R., Aziz, R. A., An accurate potential energy curve for helium based onab initia calculations, J. Chem. Phys., 1997, 107(3): 914.
Nellis, W. J., Holes, N., Mitchell, A. C. et al., Shock compression of liquid helium to 56 GPa (560kbar), Phys. Rev. Lett., 1984, 53(13): 1248.
Loubeyre, P., Letoullec, R., Pinceaux, J. P. et al., Equation of state and phase diagram of solid4 He from single-crystal X-ray diffraction over a large P-T domain, Phys. Rev. Lett., 1993, 71(14): 2272.
Lingcang, C., Fusheng, L., Fuqian, J., Theoretical isothermal compression curve for solid helium, J. High Pressure Physics (in Chinese), 1998,12(2): 145.
Car, R., Parrinello, M., Unified approach for molecular dynamics and density-functional theory, Phys., Rev. Lett., 1985, 55 (22): 2471.
Kuijper, A., Vos, W. L., Barrat, J. L. et al., Freezing of simple systems using density functional theory, J. Chem. Phys. 1990,93(7): 5187.
Hoover, W. G., Computational Statistical Mechanics, Amsterdam: Elsevier Science Publishers. B. V., 1991, 1–42.
Peter, J. K., Jan, A. S., Equation of state of fluid helium to very high pressure, J. Chem. Phys., 1991, 95(6): 4519.
Mao, H. K., Hemley, R. J., Wu, Y. et al., High-pressure phase diagram and equation of state of solid helium from singlecrystal X-ray diffraction to 23.3 GPa, Phys. Rev. Lett., 1988, 60(25): 2649.
Toullec, R. L., Loubeyre, P., Pinceaux, J. P., Refractive-index measurements of dense helium up to 16 GPa atT = 298 K: Analysis of its thermodynamic and electronic properties, Phys. Rev. B, 1989,40(4): 2368.
Yujun, Z., Ming, J., Peilin, C.,Ab initio molecular dynamics, Progr. in Phys. (in Chinese), 1998, 18(1): 47.
Aziz, R. A., Nain, V. P., Carley, J. S. et al., An accurate intermoleeular potential for helium, J. Chem. Phys., 1979, 70 (9): 4330.
Ross, M., Young, D. A., Helium at high density, Phys. Lett. A, 1986, 118(9): 463.
Ree, F. H., Simple Molecular Systems at Very High Density(eds. Polian. A., Loubeyre, P., Boceara, N.), New York: Plenum, 1989, 87–90.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Cai, L., Chen, Q., Jing, F. et al. Compression behavior and structure of dense helium at high temperatures by molecular dynamics simulation. Sci. China Ser. A-Math. 43, 539–544 (2000). https://doi.org/10.1007/BF02897146
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02897146