Solvation of Na+ in argon clusters

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Understanding the behavior of metal ions in non-polar solvents is crucial for various chemical and physical processes.
• Argon clusters provide a simplified model system to study solvation effects on metal ions.

Purpose of the Study:

• To investigate the structural evolution and stability of sodium ion (Na+) doped argon clusters (Ar(n)Na+) up to n=54.
• To determine the coordination number and geometry of the sodium ion within the argon solvent shell.

Main Methods:

• Atomistic potentials were developed and validated against ab initio coupled-cluster calculations for smaller clusters.
• Polarization effects were modeled using induced dipoles and a fluctuating charges model.
• Axilrod-Teller three-body interactions were incorporated to account for interatomic forces.

Main Results:

• Both polarization models predicted similar cluster growth patterns.
• A significant structural transition in sodium ion coordination was observed around n=50.
• The coordination geometry shifted from a square antiprism (coordination number 8) to an icosahedron (coordination number 12).

Conclusions:

• Intrasolvent constraints within the argon cluster drive the observed structural transition.
• The findings provide insights into the size-dependent solvation and coordination behavior of metal ions in atomic clusters.