Ab initio calculations on the structure, vibrational frequencies, and valence excitation energies of the benzene…Ar and benzene…Ar2 cluster

Excitation spectra of van der Waals (vdW) clusters show spectral shifts due to change in the stabilization energy in the ground and excited state. Ab initio calculations are applied to determine the structure and vibrational frequencies of vdW clusters like benzene…Ar and benzene…Ar2 in the electronic excited state. The calculation gives values for the valence excitation energy and intermolecular vibrations which are in good agreement with experimental data.