Long-range interactions between polar bialkali ground-state molecules in arbitrary vibrational levels

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Physical Chemistry

Background:

• Van der Waals interactions are crucial for understanding molecular behavior, especially in ultracold systems.
• Accurate calculation of C6 coefficients is essential for modeling long-range interactions between molecules.

Purpose of the Study:

• To calculate isotropic C6 coefficients for heteronuclear alkali-metal diatomic molecules.
• To investigate the validity of the Moelwyn-Hughes approximation for molecules in different vibrational states.

Main Methods:

• Employed the sum-over-state formula from second-order perturbation theory.
• Utilized experimental and quantum-chemical data for potential energy curves and transition dipole moments.
• Calculated contributions from ground-state transitions, ground-to-excited state transitions, and a crossed term.

Main Results:

• Determined C6 coefficients for ten alkali-metal diatomic species (Li, Na, K, Rb, Cs).
• Demonstrated the validity of the Moelwyn-Hughes approximation for molecules in different vibrational levels when applied to each sum-over-state contribution.
• Provided data relevant for ultracold molecule collision dynamics.

Conclusions:

• The calculated C6 coefficients offer precise insights into long-range interactions.
• The validated Moelwyn-Hughes approximation simplifies calculations for systems with varying vibrational states.
• Results are significant for research on ultracold bialkali molecule collisions.