Figure 2. Potential energy surfaces (PESs) as a function of
intermolecular distance, R , (left) and rotational angle,θ , around the normal axis to the molecular plane of the carbazole
at its center of mass (right) for the ground (S0) and
excited (T1/S1) states calculated with
6-311+G(d) basis set at SOS-MP2 and SOS-CIS(D0) levels,
respectively; in case of PES as a function of θ , the
intermolecular distances correspond to the respective equilibrium
distances. The calculated singlet and triplet vertical excitation
energies of the carbazole at this level are ca. 4.23 and 3.69 eV,
respectively.