Long-range interactions between an atom in its ground S state and an open-shell linear molecule.

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Intermolecular Forces

Background:

• Understanding long-range interactions is vital for controlling atom-molecule systems.
• Sympathetic cooling experiments require accurate theoretical models of these interactions.

Purpose of the Study:

• To develop a comprehensive theory for long-range interactions between ground-state atoms and linear molecules in degenerate states.
• To relate long-range interaction coefficients to fundamental molecular properties, including multipole polarizability tensors.
• To investigate additional induction energy terms for excited molecular states.

Main Methods:

• Theoretical framework for calculating long-range interaction coefficients.
• Inclusion of all components of static and dynamic multipole polarizability tensors.
• Extension to include nondiagonal tensor components and interactions involving excited molecular states.

Main Results:

• Formulas derived for long-range coefficients based on first and second-order molecular properties.
• Demonstrated the importance of all multipole polarizability tensor components, including off-diagonal terms.
• Identified additional induction energy terms for excited molecular states.

Conclusions:

• The presented theory provides a robust framework for understanding atom-molecule interactions.
• Numerical results for Rb-CO, Rb-OH, Rb-NH, Rb-CH, and Li-CH systems are relevant for sympathetic cooling applications.
• The theory accurately accounts for complex electronic structures and interactions.