According to the recently discovered phenyl- cyclopentadienyl (PCP) rule, the intensity of cyclic conjugation in the five-membered ring of acenaphthylene and fluoranthene-type polycyclic conjugated hydrocarbons increases with the number of PCP fragments present in the molecule. We now tested this rule by DFT calculations at the B3LYP/6-31G(d) level of theory and confirmed its validity.