  Isotropic soft-core potentials with two characteristic length scales have
been used since 40 years to describe systems with polymorphism. In the recent
years intense research is showing that these potentials also display
polyamorphism and several anomalies, including structural, diffusion and
density anomaly. These anomalies occur in a hierarchy that resembles the
anomalies of water. However, the absence of directional bonding in these
isotropic potentials makes them different from water. Other systems, such as
colloidal suspensions, protein solutions or liquid metals, can be well
described by these family of potentials, opening the possibility of studying
the mechanism generating the polyamorphism and anomalies in these complex
liquids.
