Ab initio configuration interaction singles (CIS) study on polycyclic aromatic molecules (I): Correlation between calculated and observed excitation energies

A series of configuration interaction singles (CIS) calculations have been performed for low-lying excited states (1La, 1Lb, and 3La) of 11 basic polycyclic aromatic hydrocarbons (PAHs) and 12 anthracene derivatives. A comparison of the calculated excitation energies to the experimentally observed values has revealed remarkable linear correlations between them, depending on the respective types of the excited states. The linear correlations were utilized to estimate the experimentally inaccessible 1Lb excitation energies of S1(La) PAHs.