Ionic liquids from Car-Parrinello simulations, part I: liquid AlCl3

Area of Science:

• Computational chemistry
• Materials science
• Physical chemistry

Background:

• Understanding the structure-property relationships of aluminum chloride (AlCl3) is crucial for its applications.
• Investigating isolated clusters and bulk systems provides insights into liquid-phase behavior.

Purpose of the Study:

• To investigate the structural properties of isolated AlCl3 clusters and their relevance to the bulk liquid.
• To determine the dominant connectivity motifs and cluster sizes in liquid AlCl3.

Main Methods:

• Static and dynamic electronic structure calculations.
• Local dipole moment analysis.
• Quantum cluster equilibrium approach.

Main Results:

• Identified dominant edge connectivity in AlCl3 dimers and corner connectivity in trimers.
• Observed ring structures and cooperative effects in trimers.
• Determined that edge connectivity dominates in liquid AlCl3, with dimers being the most abundant species, alongside trimers, tetramers, and pentamers.

Conclusions:

• Energetic considerations of static clusters alone are insufficient to explain liquid-phase AlCl3 behavior.
• Quantum cluster equilibrium or simulations are necessary for accurate representation of liquid AlCl3 properties.
• Edge connectivity is confirmed as dominant in liquid AlCl3, with a minor presence of corner connectivity, likely from trimers.