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

Abstract

In this paper we investigate the phase diagram of a dumbbell model composed of two hard-core soft-corona beads through $NpT$ simulations. This particular system was chosen due to its ability to exhibit a diverse range of stripe patterns. 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 stripes patterns. Notably, not only do the structural properties exhibit intriguing behavior, but the diffusion and density in the nematic fluid phase also displays a water-like anomalous increase under compression. Those findings can be valuable in guiding the design of materials based on nanoparticles, with the aim of achieving specific mesopatterns.