where E b is the barrier height between two local minima at x = ±x 0 . The second term on the r.h.s. of Eq. ( ) describes the dipole-dipole interaction between the ith and i ′ th molecule with the strength ∆ ii ′ . The vectorial molecular dipole moments ⃗ µ i (x i ) are projected onto the electronic ground state. Every molecule is surrounded by a multitude of solvent molecules. Therefore, we assume that every molecule is coupled to its own environment, which is modeled as a bosonic bath comprising an infinite number of harmonic oscillators,