We now compare the correlation functions calculated by TD-DMRG with those It is known that LF/VPT theory is valid in the strong coupling regime. These polaron transformation methods can reproduce the hopping behavior as described by Fermi's golden rule for 𝜏𝜏 ≪ 𝜆𝜆 . These can also reproduce the bandlike behavior as described by Boltzmann transport equation when 𝜆𝜆 is negligible, as demonstrated previously (see Supporting Information 5). As shown in Figs. 3(a), 3(b), 3(i), and 3(j), the correlation functions calculated by TD-DMRG coincide impressively with analytic solutions in both strong coupling regime and zero coupling limit, which proves TD-DMRG's validity and accuracy. Meanwhile, the correlation functions calculated by TD-DMRG are quite different from analytic formula in intermediate regime plotted in Fig. (c)-3(f), and larger 𝜏𝜏 leads to more obvious difference. Recall Eq. ( ), the large difference in correlation functions will lead to large difference in transport coefficients.