To broaden the configurational space beyond alkene bond rotations, we employed Wigner sampling to encompass vibrational degrees of freedom. Initially, we sampled geometries (6 for ethene/propene and 13 for butene), covering rotations around the alkene double bond. These geometries and their associated harmonic frequencies (cf. previous section) serve as the foundation for generating a set of non-equilibrium structures sampled from a Wigner probability distribution function. In brief, each of the 3N -6 normal mode coordinates and momenta (N . . . number of atoms) is randomly sampled according to a probability distribution function. The respective sampled normal-mode coordinates and momenta are then converted into Cartesian coordinates and velocities. The Wigner sampling calculations were performed with the initial conditions program integrated into the SHARC 3.0 package. Using the normal mode coordinates of the PBE0 equilibrium and non-equilibrium structures as input for the Wigner distribution, we generated a total of 6,000 and 13,000 geometries for ethene/propene and butene, respectively (cf. Figure ). These geometries were equally distributed into the different configurations on the initial path scanning the alkene bond rotation. For example, for butene, 1000 geometries were created for the cis and trans-isomer and the nine interpolated geometries that connect these two isomers.