2003/12/16 by E. Daykova, Ana Proykova
Physics and Astronomy · #physics.atm-clus
published as "Meetings in Physics@University of Sofia", v.4 (2003)p.32 (Heron Press Science Series, ISBN 954-580-138-7) · 7 pages, 10 figures, Latex
arxiv created 2003/12/16 · arxiv updated 2009/12/01
Low-temperature (below 60K) phase changes of free clusters containing 50, 137, and 229 methane molecules have been observed in isoenergetic Molecular Dynamics computations. Bulk solid methane exhibits structural phase transformation at 20.4 K. However, clusters of 50 molecules already melt at about 25 K, which makes the observation of solid-solid transformations rather challenging. Molecular Dynamics calculations of isoenergetic free methane clusters show that they exhibit transformations from an orientationally-ordered (~ 10K) and a disordered phase (above 20K). There is no hysteresis in the cooling-heating regime - a signal for continuous transition.