The BLG layers are found to fluctuate in the intermediate region between the AB and AA stacking configurations, with a preference for the AB stacking at high pressure (4.9-10 GPa). Note that sp 2 -to-sp 3 phase change in BLG has recently been reported regardless of the stacking configuration. Finally, we coupled ab initio MD simulations, via the Plumed plugin, with the metadynamics algorithm, that accelerates the escape from local free-energy minima and allows reconstructing free-energy landscapes by adding to the potential energy of the system a historydependent bias profile built as a sum of repulsive Gaussian functions, acting in a lowdimensional space of collective variables.