In this work, we mimic a slowly decaying nonadiabatic phenomenon in the weak coupling limit. We achieve it by constructing the SBH with 10 Harmonic bath modes, each with 1 amu mass. The cut-off frequency is chosen as 𝜔 𝑚𝑎𝑥 = 3𝜔 𝑐 = 3100 cm -1 . The reorganization energy is set to 𝐸 𝑟 = 0.0125. The isolated two-level system is formed by setting the energy bias as 0.02 a.u. and the diabatic coupling as 0.001 a.u.