Infrared absorption line strengths of the Na⋯FH van der Waals molecule

The dipole moment function of the Na⋯FH van der Waals molecule obtained in accurate multireference configuration interaction calculations and the recently published ab initio potential energy surface for NaFH [Topaler et al., J. Chem. Phys. 108, 5349 (1998)] have been used to predict the infrared absorption line strengths of Na⋯FH for several fundamental and overtone transitions. The fundamental excitation of the HF stretch mode in Na⋯FH is enhanced by a factor of 2.2 compared to the isolated HF molecule, and the first and second overtones are enhanced by factors of 21 and 53, respectively.