Figure 2: Arrhenius plots of the thermal rate constant for the reaction. The solid line is the quantum instanton rate. Dotted and dashed lines are the Arrhenius fits of the experimental data from [47, 48], respectively. The dot-dashed line is the result of the multiconfigurational time-dependent Hartree approach (MCTDH) . The open squares are the results of the canonical variational theory with microcanonical optimized multidimensional tunneling (CVT/μOMT) .