Metadynamics (MetD) bias, in kcal mol⁻¹, necessary for converting, at 650 K, HCHO and HCN into glycolonitrile (reaction (1)). Abscissa S represents the progress of the reaction; S ∼ 1.14 refers to a region of the collective variable (CV) space close to the reactants. As reported in the legend, gaussian heights of 2.4 kcal mol⁻¹ have been deposed every 50 fs of AIMD exploiting the BLYP-D3(BJ) exchange and correlation functional.