Linear response coupled cluster study of the benzene excimer

The hierarchy CC2, CCSD and CCSDR(3) of linear response coupled cluster methods is used to study the electronic states of the benzene dimer related with the emission, absorption and interaction energy of the benzene excimer. Differential electron density plots are used to give insights into the stabilizing interactions within the benzene excimer. The CC2 level describes properly most of the addressed spectroscopic parameters, partially due to error cancellations. High accuracy is obtained if the triple excitations are considered at the CCSDR(3) approximation together with corrections for large basis sets. A detailed and critical comparison between theory and experiment is presented.