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oai:recercat.cat:2445/188492025-11-19T20:27:16Zcom_2072_1057col_2072_478822col_2072_478917

00925njm 22002777a 4500 dc Franzese, Giancarlo author Malescio, Gianpietro author Skibinsky, Anna author Buldyrev, V. S. (Vladimir Sergeevich) author Stanley, H. Eugene (Harry Eugene), 1941- author 2011-07-07T12:53:58Z 2011-07-07T12:53:58Z 2003 We investigate the phase behavior of a single-component system in three dimensions with spherically-symmetric, pairwise-additive, soft-core interactions with an attractive well at a long distance, a repulsive soft-core shoulder at an intermediate distance, and a hard-core repulsion at a short distance, similar to potentials used to describe liquid systems such as colloids, protein solutions, or liquid metals. We showed [Nature (London) 409, 692 (2001)] that, even with no evidence of the density anomaly, the phase diagram has two first-order fluid-fluid phase transitions, one ending in a gas¿low-density-liquid (LDL) critical point, and the other in a gas¿high-density-liquid (HDL) critical point, with a LDL-HDL phase transition at low temperatures. Here we use integral equation calculations to explore the three-parameter space of the soft-core potential and perform molecular dynamics simulations in the interesting region of parameters. For the equilibrium phase diagram, we analyze the structure of the crystal phase and find that, within the considered range of densities, the structure is independent of the density. Then, we analyze in detail the fluid metastable phases and, by explicit thermodynamic calculation in the supercooled phase, we show the absence of the density anomaly. We suggest that this absence is related to the presence of only one stable crystal structure. Cristal·lografia Propietats tèrmiques Equacions d'estat Transformacions de fase (Física estadística) Crystallography Thermal properties Equations of state Phase transformations (Statistical physics) Metastable liquid-liquid phase transition in a single-component system with only one crystal phase and no density anomaly