Curved stacking pathways along the <i>γ</i>-surface of diamond

Diamond, the hardest natural crystal, has attracted significant attention for its plasticity, which is believed to be influenced by its stacking faults. Studies have mainly focused on one-dimensional linear pathways in stacking transitions, neglecting its transverse freedom on the main slip plane. However, in an actual stacking process, stacking faults can follow curved lines along the slip plane rather than being constrained to straight lines. In this study, using ab initio calculations, we mapped the \ensuremath{\gamma}-surface, defined as the landscape of generalized stacking fault energies, along the weakest direction of the {111} orientation in diamond. We then applied the nudged elastic band method on diamond's \ensuremath{\gamma}-surface to determine the minimum energy paths for both the stacking and dislocation processes, finding significantly reduced stacking energy barriers compared to previous reports (for the glide set, our energy barrier is only one-third of that for the traditional direct path). Our calculations reveal that the glide set can round its high-energy peak, with a lower energy barrier across the entire stacking plane than the shuffle set. Our results provide alternative insights into the plasticity and stacking faults of diamond, advancing the understanding of the transition in superhard carbon materials, especially diamond under shear stress.