• • NNAP-guided simulations lower the energy barrier for β→α transformation by nearly 60% compared to DFT predictions, enabling large-scale atomistic simulations of phase transformations in Si3N4.
• • The bilayer cooperative transformation pathway exhibits an energy barrier of 0.018 eV/Ų, which is 10% lower than the independent layer-by-layer pathway (0.020 eV/Ų), as quantified by CI-NEB calculations.
• • The energy barrier for the bilayer cooperative pathway shows robust convergence with respect to system size, as shown in Fig. S11, ensuring reliability of the mechanism across scales.
• • The bilayer cooperative mechanism involves concerted breaking and reformation of Si–N bonds with coordinated rotations of Si atoms, leading to vertically aligned nucleation domains that delocalize transformation strain and reduce kinetic barriers, aligning with experimentally observed abnormal plasticity.