An ubiquitous mechanism for waterlike anomalies
  Using collision driven molecular dynamics a system of spherical particles interacting through an effective two length scales potential is studied. The potential can be tuned by means of a single parameter, $\lambda$, from a ramp $(\lambda=0.5)$ to a square-shoulder potential $(\lambda=1.0)$ representing a family of two length scales potential in which the shortest interaction distance has higher potential energy than the largest interaction distance. For all the potentials, ranging between the ramp and the square-shoulder, density and structural anomalies were found, while the diffusion anomaly is found in all but in the square-shoulder potential. The presence anomalies in square-shoulder potential, not observed in previous simulations, confirm the assumption that the two length scales potential is an ubiquitous ingredient for a system to exhibit water-like anomalies 
Alan Barros de Oliveira, Paulo A. Netz, and Marcia C. Barbosa