A new insight on the structural changes of linear quadrupole liquids

Area of Science:

• Computational physics
• Materials science
• Chemical physics

Background:

• Understanding molecular behavior in condensed phases is crucial for materials design.
• Linear quadrupoles significantly influence intermolecular interactions and phase transitions.
• Previous studies have explored simple models, but complex molecular behaviors require advanced simulation.

Purpose of the Study:

• To investigate the effects of molecular length and quadrupole moments on the structure of linear quadrupole liquids.
• To analyze the transition from liquid to solid phases and identify factors influencing structural changes.
• To evaluate the applicability of classical perturbation theories for these systems.

Main Methods:

• Utilizing molecular-dynamics simulations to model systems with varying molecular lengths, temperatures, densities, and quadrupole moments.
• Analyzing intermolecular orientations and structural characteristics across different thermodynamic states.
• Comparing simulation results with theoretical predictions from classical perturbation theories.

Main Results:

• Simulations covered condensed phases, with some states exhibiting solid-like features.
• A transition from parallel to perpendicular molecular orientation was observed with increasing quadrupole moments.
• This orientation change, dependent on quadrupole moment and molecular length, relates to solid structures of diatomic molecules.
• The study identified conditions for the appearance of a plastic solid phase at low quadrupole moments and densities.

Conclusions:

• Molecular length and quadrupole moments are key determinants of structural organization in linear quadrupole liquids.
• The observed orientation changes provide insights into the solid structures of diatomic molecules.
• Classical perturbation theories may have limitations for accurately describing these complex systems.