Stockmayer fluid with a shifted dipole. II. Interfacial behavior

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Soft Matter Physics

Background:

• Understanding liquid-vapor interfaces is crucial for various physical and chemical processes.
• The Stockmayer fluid model is a standard for simulating systems with both short-range repulsion and long-range dipole-dipole interactions.
• Investigating the impact of dipole asymmetry is key to refining these models.

Purpose of the Study:

• To investigate the equilibrium properties of the liquid-vapor interface in shifted-dipole Stockmayer fluids.
• To analyze the influence of dipole moment strength and asymmetry on interfacial characteristics.
• To explore molecular orientation and ordering at the interface.

Main Methods:

• Molecular dynamics simulations were performed in the canonical ensemble.
• Equilibrium interfacial properties such as density profiles and order parameters were computed.
• Angular distribution functions were calculated to analyze molecular orientation.

Main Results:

• The dipole shift significantly alters molecular orientation and polar order, while nematic order remains largely unaffected.
• A simple image-dipole construct accurately predicts the qualitative behavior of distribution functions.
• The spontaneous interfacial polarization and generated electric field can change sign with increasing dipole moment strength, inverting the interfacial potential difference.

Conclusions:

• The dipole shift in Stockmayer fluids has a profound effect on interfacial properties and molecular ordering.
• The findings highlight the sensitivity of interfacial phenomena to dipole characteristics.
• The study provides a theoretical framework and simulation insights into complex fluid interfaces.