, and C IK = E I (R) -E K (R). When the nuclear kinetic energy is not large enough to compensate the polariton potential difference, a frustrated hop occurs, meaning that the hop is rejected and the active state is set to the original adiabatic state |I . In addition, we do not modify the nuclear velocity in this case. The polariton population is calculated as the trajectory average of the active states, i.e, for a given trajectory and at a given time, a value of 0 is given for an inactive state and a value of 1 for the active state.