Which mechanism underlies the water-like anomalies in core-softened potentials?
Instituto de Física, Universidade Federal do Rio
Grande do Sul,
Caixa Postal 15051, 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
2 Instituto de Química, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre, Rio Grande do Sul, Brazil
Corresponding author: a email@example.com
Revised: 28 November 2007
Published online: 12 March 2008
Using molecular dynamics simulations we investigate the thermodynamics of particles interacting with continuous and discrete versions of a core-softened (CS) intermolecular potential composed by a repulsive shoulder. Dynamical and structural properties are also analyzed by the simulations. We show that in the continuous version of the CS potential the density at constant pressure has a maximum for a certain temperature. Similarly the diffusion constant, D, at a constant temperature has a maximum at a density and a minimum at a density , and structural properties are also anomalous. For the discrete CS potential none of these anomalies are observed. The absence of anomalies in the discrete case and its presence in the continuous CS potential are discussed in the framework of the excess entropy.
PACS: 61.20.Gy – Theory and models of liquid structure / 61.20.Ja – Computer simulation of liquid structure / 61.20.Ne – Structure of simple liquids
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008