Regensburg 2000 – scientific programme

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TT: Tiefe Temperaturen

TT 17: Postersitzung II: Pinning und Vortexdynamik (1-8), Supraleitung: Theorie (9-13), Korrelierte Elektronen (14-48), Niederdimensionale Systeme (49-68), Quantenflüssigkeiten (69-75)

TT 17.75: Poster

Wednesday, March 29, 2000, 14:30–18:00, A

Monte Carlo Study of the Crystallization of Liquid Argon — •Klaus A. Gernoth — Department of Physics, UMIST, PO Box 88, Manchester M60 1QD, United Kingdom

Results of an investigation of the spontaneous crystallization of liquid Argon at the triple point temperature into the hexagonal close-packed (hcp) solid are presented. The crystallization is studied by means of exact Fourier Path Integral Monte Carlo (FPIMC) calculations, employing a two-body interaction. At the liquid bulk density an initial hcp Ar crystal melts rapidly, whereas at the solid density the hcp Ar crystal is stable. Crystallization is explored by first scaling the liquid configuration of the Ar atoms at the liquid density to an analogous liquid configuration at the solid density. This latter configuration is the initial configuration from which an FPIMC simulation at the solid density is started. In the course of the simulation crystalline hcp Ar gradually forms from the initial liquid. The liquid and solid phases are analyzed in terms of the space group symmetries of the local one-body and two-body densities. Crystallization of the Ar liquid is established by monitoring the build-up of symmetry-breaking terms in the local one-body and two-body densities. This work is motivated in part by experiments showing that in the vicinity of the triple point temperature minute amounts of nitrogen or oxygen impurities stabilize the hcp Ar solid, although the stable phase of pure crystalline Ar is the face-centered cubic (fcc) structure. However, theories employing only two-body forces, as is the case also here, predict the hcp phase to be slightly favored in comparison to the fcc solid.