Stripes polymorphism and water-like anomaly in hard core-soft corona dumbbells

In this paper, we investigate the phase diagram of a dumbbell model composed of two hard-core soft-corona beads through NpT simulations. We chose this particular system due to its ability to exhibit a diverse range of stripe patterns. By analyzing the thermodynamic and structural changes along compression isotherms, we explore the transition between these distinct patterns. In addition to the stripe and Low-Density-Triangular solid phases obtained, we observed a Nematic Anisotropic phase characterized by a polymer-like pattern at high temperatures and intermediate pressures. Furthermore, we demonstrate the significant role played by the new characteristic length scale, which arises from the anisotropic geometry of the dumbbell structure, in the transition between the stripe patterns. Notably, not only do the structural properties exhibit intriguing behavior, but the diffusion and density in the nematic fluid phase also display a water-like anomalous increase under compression. These findings can be valuable in guiding the design of materials based on nanoparticles, with the aim of achieving specific mesopatterns.