Corresponding figures for CASSCF and RMS-CASPT2 and x and y vectors for all levels are provided in Figures and, respectively, in the Supporting Information. In Figure , x and y represent linear combinations of the (orthonormalized) gradient difference and NAC vectors, with displacement along these vectors lifting the degeneracy. The x and y approximately correspond to in-plane and out-of-plane modes, respectively. The P CoIn and B CoIn parameters 56 are summarized in Table . The relatively large P CoIn values (P CoIn > 1) indicate that these MECoIns are strongly sloped, which is evident from the steeply tilted PESs in Figure (a). The B CoIn values, which classify conical intersections as bifurcating or single-path, are all greater than one, signify-ing that these are single-path conical intersections, implying the local topography directs toward a single product. Comparing these parameters in vacuum and water, the solvent effect does not significantly impact the local topography in this example. Figure (b) shows the XMS-CASPT2 energy difference between S 0 and S 1 around the CASSCF MECoIn. Since the CASSCF energy is made invariant with respect to rotations between crossing states (Eq. ( )), and XMS-CASPT2 are strictly invariant to such rotations in the model space (except for minor non-invariance in the first-order interacting space), the PESs at the CASPT2 level with PCM are smooth. It should be noted that the discontinuities discussed in this study are strictly related to the electronic structure. PCM introduces other sources of discontinuity, such as the creation and annihilation of tesserae and electrostatic interactions between tesserae, which are beyond the scope of this study.