Quantum mechanical characterization of the He4ICl weakly bound complex.

Area of Science:

• Quantum chemistry
• Atomic and molecular physics
• Condensed matter theory

Background:

• Van der Waals complexes are crucial for understanding intermolecular forces.
• Helium clusters provide a unique, weakly interacting environment for studying guest molecules.
• Investigating mixed clusters like He4ICl reveals complex interplay of interactions.

Purpose of the Study:

• To perform detailed vibrational calculations on the He4ICl van der Waals complex.
• To determine the most stable structural configurations and energetics of the cluster.
• To compare theoretical predictions with experimental data for validation.

Main Methods:

• Utilized the multiconfiguration time-dependent Hartree (MCTDH) method for 12-dimensional vibrational calculations.
• Employed natural potential fits for the potential energy operator and a mode combination scheme for computational efficiency.
• Represented the potential energy surface using ab initio parametrized terms for He-ICl and He-He interactions.

Main Results:

• Calculated zero-point energy, binding energies, and vibrationally averaged structures for various He4ICl isomers.
• Identified the (3,1,0) structure (three He atoms near T-shaped, one linear) as the most stable configuration.
• Observed higher anisotropy in the potential energy surface compared to homonuclear dopant clusters.

Conclusions:

• The (3,1,0) structure's stability is confirmed, consistent with recent experimental findings.
• The study highlights the influence of potential topology on cluster structure and energetics.
• Discussed the stability of higher-order conformers in relation to the potential surface's multiple minima.