A full-dimensional ab initio potential energy surface and rovibrational spectra for the Ar–SO₂ complex

Abstract

We present a full-dimensional potential energy surface for Ar–SO₂ which involves three intramolecular $Q_{1}$, $Q_{2}$ and $Q_{3}$ normal modes for the $\nu_{1}$ symmetric stretching, $\nu_{2}$ bending and $\nu_{3}$ asymmetric stretching vibrations of SO₂. The intermolecular potential was computed at the [CCSD(T)]-F12a level with aug-cc-pVTZ basis set plus the midpoint bond functions (3s3p2d1f1g). Three vibrationally averaged potentials of Ar–SO₂ with SO₂ in the ground state as well as the $\nu_{1}$ and $\nu_{3}$ excited states were generated by integrating three intramolecular coordinates. Each potential has a global minimum with the non-planar geometry and two saddle points. The radial discrete variable representation (DVR)/angular finite basis representation (FBR) method and Lanczos algorithm were utilized to calculate the rovibrational bound states and energy levels of Ar–SO₂. The vibrational band origin shifts for this complex in the $\nu_{1}$ and $\nu_{3}$ regions of SO₂ were determined to be − 0.0970 and − 0.7537 cm⁻¹, respectively. The calculated origin shifts as well as the microwave and infrared transition frequencies agree well with available experimental results.