How does flexibility shape anomalies in core-softened dimeric fluids?

Area of Science:

• Soft Matter Physics
• Computational Chemistry
• Liquid State Theory

Background:

• Many liquids exhibit water-like anomalies due to competing interactions.
• Isotropic core-softened (CS) models capture these anomalies but lack anisotropy and flexibility.
• Anisotropy and flexibility are crucial for understanding complex fluid behavior.

Purpose of the Study:

• Investigate the impact of bond stiffness on anomalous behavior in dimeric CS fluids.
• Determine how tuning bond stiffness from flexible to rigid affects density, diffusion, and structure.
• Establish bond stiffness as a key parameter for controlling anomaly-driven phenomena.

Main Methods:

• Simulations of dimeric core-softened (CS) models with varying bond stiffness (k).
• Analysis of density, diffusion coefficients, and radial distribution functions.
• Characterization of structural order and emergent length scales.

Main Results:

• Increased bond stiffness shifts the temperature of maximum density to lower temperatures.
• Rigidity narrows diffusion anomalies to lower temperatures and modifies structural order.
• Emergent geometric length scales appear in the center-of-mass radial distribution function, altering the hierarchy of distances.

Conclusions:

• Bond stiffness is a critical parameter for tuning anomalous behavior in anisotropic soft matter.
• A three-scale competition (two radial, one geometric) explains correlated shifts in anomalies.
• This work provides a unified framework for understanding anomaly-driven phenomena in complex fluids.