We assessed the convergence of the electronic PES with respect to supercell and k-mesh sizes. We conducted a similar test as in Section 5.1, shifting the layers as shown in Figure . The electronic PES is reported for different supercell sizes and k-meshes in Figure (SI). We obtain practically identical PESs using a unit cell in combination with a k-point mesh of 1 × 1 × 3 (KP setup) and a 1 × 1 × 2 supercell (SC setup). However, the KP setup enforces higher symmetry in the z-direction during the AIMD simulation, while the layers 1' and 2' can move independently from the layers 1 and 2 in the SC setup (see Figure for the labels.)