Liquid crystal phase and waterlike anomalies in a core-softened shoulder-dumbbells system

TL;DR

This study uses molecular dynamics to explore how diatomic shoulder-dumbbell molecules with core-softened interactions exhibit waterlike anomalies, phase behavior, and liquid crystal formation, revealing the impact of molecular anisotropy.

Contribution

It introduces a detailed analysis of thermodynamic, dynamic, and structural anomalies in a dumbbell system, highlighting the effects of anisotropy on phase behavior and anomalies.

Findings

Presence of density maxima at constant pressure

Mobility shows non-monotonic behavior with density

Emergence of liquid crystal phase due to anisotropy

Abstract

Using molecular dynamics we investigate the thermodynamics, dynamics and structure of 250 diatomic molecules interacting by a core-softened potential. This system exhibits thermodynamics, dynamics and structural anomalies: a maximum in density-temperature plane at constante pressure and maximum and minimum points in the diffusivity and translational order parameter against density at constant temperature. Starting with very dense systems and decreasing density the mobility at low temperatures first increases, reach a maximum, then decreases, reach a minimum and finally increases. In the pressure-temperature phase diagram the line of maximum translational order parameter is located outside the line of diffusivity extrema that is enclosing the temperature of maximum density line. We compare our results with the monomeric system showing that the anisotropy due to the dumbbell leads to a much larger solid phase and to the appearance of a liquid crystal phase. the double ranged thermodynamic and dynamic anomalies.