The excited-states intermolecular potential energy surfaces of the Ar-CS2 van der Waals complex: Ab initio study

- We perform ab initio calculations of Ar-CS2 PESs in 16 excited states.
- All reported intermolecular potentials are vertical ones.
- Some of the PESs are fitted to an analytical expression.
- The simulation spectrum of Ar-CS2 complex is presented.
- Due to the presence of Ar, some CS2 forbidden transitions become possible.

The sixteen lowest potential energy surfaces (PESs) of the electronically excited Ar-CS2 van der Waals (vdW) complex are calculated in the singlet state. PESs are obtained based on the vertical excitation of the complex containing the linear geometry ground electronic state (1Σg+) of CS2 molecule to the valence excited electronic states. The computational method involves EOM-CCSD with the aug-cc-pVDZ basis set augmented with a set of midbond functions (3s3p2d1f1g). It was found that some forbidden electronic transitions like 1Σg+→1Πg in the CS2 monomer become possible due to the presence of the Ar atom. The interaction PESs with the visible well-depth for all of the configurations are globally fitted to an analytic function in order to estimate the isotropic dipole-dipole (C60) and dipole-quadrupole (C80) coefficients of the excited states of the complex.