Fig. 3. Atomistic model of the diamond.

The simulation box consists of five diamond unit cells in each direction, whose primary crystallographic directions [1, 0, 0], [0, 1, 0] and [0, 0, 1] are aligned with the x, y, and z axes of the simulation box (a). Stress σ_i (b) and stiffness values C_ij (c) converge to their respective targets during the optimization. These results are robust to long simulation runs of 10 ns (marked with crosses). The stress–strain curve over normal natural strains e₁ agrees with density functional theory (DFT) data⁴⁷ for medium-sized strains (e₁ < = 0.02), but deviates for large strains due to limited extrapolation capabilities of neural network potentials (d).