Regensburg 1998 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 46: POSTER II
DY 46.67: Poster
Donnerstag, 26. März 1998, 14:30–17:30, B
Quantum Monte Carlo Study of Phase Transitions in Molecular Solids (N2 and N2-Ar mixtures) — •M. Presber, D. Löding, R Martonak, and P. Nielaba — Institut für Physik, Johannes–Gutenberg Universität Mainz, Staudinger–Weg 7, D–55099 Mainz
Molecular solids composed of N2–molecules are studied by path integral Monte Carlo simulations in the constant-stress ensemble utilizing Lennard–Jones and electrostatic interactions. Quantum effects on molar volumes and transition temperatures are quantified for different values of the external pressure. At zero pressure the transition temperature from a high-temperature orientationally-disordered cubic phase to a low-temperature phase with Pa3 structure is reduced by about 11 % due to quantum delocalization. With increasing Trotter number, the molar volume at low temperatures approaches the experimentally observed values, in contrast to the classical simulations. With increasing pressure the transition temperature is shifted to larger values and the difference between the classical and quantum values is decreasing.