Theoretical investigation of potential energy surface and bound states for the van der Waals complex Ar-BrCl dimer

- A two-dimensional potential for Ar-BrCl is constructed at the CCSD(T) level.
- The PES is characterized by three minima and two saddle points between them.
- Bound state calculations were carried out for the complex.

The intermolecular potential energy surface (PES) of the ground electronic state for the Ar-BrCl dimer is constructed at the CCSD(T) level with the aug-cc-pVQZ basis set and mid-bond functions. The PES is characterized by three minima and two saddle points. The global minimum corresponding to a collinear Ar-BrCl configuration, which has been observed experimentally, is located at R = 4.10 Å and θ = 2.5° with a well depth of −285.207 cm−1. A nearly T-shaped structure and an anti-linear Ar-ClBr geometry is also predicted. The bound state calculations are preformed to study intermolecular vibrational modes, rotational levels and average structures for the complex. Our transition frequencies, spectroscopic constants and average structures for all isotopomers of the collinear isomer agree well with experimental data. We have also provided pure rotational transitional frequencies for both nearly T-shaped and anti-linear isomers. These results are significant for further experimental investigations of the Ar-BrCl dimer.