the similarity between the two profiles (especially in the near-TS region). However, from a quantitative perspective, the EPS-derived entropic profiles with 124 trajectories significantly deviate from the reference. Specifically, the overall variation of entropy (i.e., -TS) goes beyond The entropy maximum (or the minimum of the -TS curve) coincides with the region of flat potential energy surface where long-lived dynamic intermediates (i.e., up to 240 fs) roam around. This region embodies larger variety of molecular conformations than the steep potential energy region near product formation. This region is also where one may identify entropic intermediates or entropic maxima. BGAN-EPS method tends to prioritize generating pseudo-molecular configurations in the entropy maximum region, thus reproducing the depth of entropic trap with high accuracy (Supporting Information, Table ). Notably, upon further bond formation below 2.0 Å, we observed slight deviation of BGAN-EPS-derived entropic profiles from the reference because of relatively small number of geometries incorporated in the structural ensemble nearby the product forming region.