Weakly bound NeHF

Abstract

We have used ab initio methods to characterize the Ne–HF van der Waals complex. The interaction energy was determined using size consistent, correlated CEPA wave functions expanded in a Gaussian basis chosen to represent both intraatomic effects and the low order multipole moments and polarizabilities of Ne and HF. The calculated well depths are −65 cm⁻¹ for linear Ne–HF and −39 cm⁻¹ for linear Ne–FH, with an intervening saddle point at −27 cm⁻¹. The induction contribution to the energy is significantly greater for Ne–HF than for Ne–FH, but dispersion remains the dominant attraction over the region of interest. Converged variational and close‐coupling calculations using the ab initio potential surface reveal three bound levels of the Ne–HF stretch mode, and several metastable levels correlating asymptotically with rotationally excited HF( j=1). Though nearly degenerate, the lifetimes of the two metastable Π (body frame Λ=±1) bending levels differ markedly because of different rotational coupling strengths to the Σ (body frame Λ=0) bending state, which undergoes rapid rotational predissociation. From the calculated line positions, widths, and intensities we have synthesized far infrared and infrared spectra of Ne–HF and Ne–DF.