https://doi.org/10.1140/epjb/e2008-00101-6
Which mechanism underlies the water-like anomalies in core-softened potentials?
1
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 marcia.barbosa@ufrgs.br
Received:
9
September
2007
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