Fig. 3: Potential energy curves for QC and NBD along the LIICs.
From: Ultrafast electronic relaxation pathways of the molecular photoswitch quadricyclane
Potential energy curves for the ground state S0 and excited states S1–S5, as well as the cation ground state D0 and first excited state D1 (dashed lines), calculated along the LIICs, first from QC to the S1/S0 MECI and then from the MECI to NBD, using RMS-CASPT2(2,6)/6-31G* + D (Methods and Supplementary Section 2.1). The two proposed reaction pathways are indicated schematically by black arrows, with the slow Rydberg pathway supporting vibrational motions on the Rydberg states before relaxing via the S1 state, while the fast valence pathway descends on S1, bypassing the MECI on the initial descent, before crossing onto the S0 ground state to form both products. The molecular geometry at the MECI has a distinct rhombic distortion (Extended Data Fig. 3). The Estorage indicates the energy stored in QC relative to NBD (~1 eV). Corresponding vertical excitation energies are listed in Table 1, and a plot including higher excited states and the approximate state characters is provided in Extended Data Figure 4.
