Description of the data and file structure This dataset provides the SPTC predictions generated by sptc-ai (extended .xyz files) and the corresponding coarse-grained finite-element meshes produced by sptc2fem (.xdmf visualization files with associated .h5 files). These data correspond to the models discussed in the main manuscript. In addition to the eight models presented in the manuscript, we also include an additional single-pillar nanopillar structure (not shown in the manuscript). - Atomic structures (.xyz) are best visualized with OVITO.- FE meshes (.xdmf/.h5) are best visualized with ParaView. Folder and file descriptions sptcai/ — atomic structures (`*.pred.xyz`) Filename Description (figure label in manuscript) 1_AC.pred.xyz 2,022-atom amorphous–crystalline Si structure (Fig. 2A) 2_GB.pred.xyz 223,930-atom Si twin grain-boundary nanowire (Fig. 2C) 3_Pxtal.pred.xyz 134,923-atom polycrystalline Si nanowire (Fig. 2D) 4_NP1.pred.xyz 26,191-atom Si (4-pillar) nanopillar structure (Fig. 2E) 5_NP2.pred.xyz Additional 6,531-atom Si (single-pillar) nanopillar structure (not in manuscript) 6_Ptype600.pred.xyz 3C/2H Si polytype structure at 600 °C (Fig. 5A, left) 7_Ptype700.pred.xyz 3C/2H Si polytype structure at 700 °C (Fig. 5B, left) 8_Ptype900.pred.xyz 3C/2H Si polytype structure at 900 °C (Fig. 5C, left) 9_Ptype1000.pred.xyz 3C/2H Si polytype structure at 1000 °C (Fig. 5D, left) sptc2fem/ — FE meshes (`*.xdmf` + `*.h5`) Filename Description (figure label in manuscript) 1_AC_mesh.xdmf (+ *.h5) 2,022-atom amorphous–crystalline Si structure (Fig. 3A) 2_GB_mesh.xdmf (+ *.h5) 223,930-atom Si twin grain-boundary nanowire (Fig. 4A) 3_Pxtal_mesh.xdmf (+ *.h5) 134,923-atom polycrystalline Si nanowire (Fig. 4B–C) 4_NP1_mesh.xdmf (+ *.h5) 26,191-atom Si (4-pillar) nanopillar structure (Fig. 4D) 5_NP2_mesh.xdmf (+ *.h5) Additional 6,531-atom Si (single-pillar) nanopillar structure (not in manuscript) 6_Ptype600_mesh.xdmf (+ *.h5) 3C/2H Si polytype structure at 600 °C (Fig. 5A, right) 7_Ptype700_mesh.xdmf (+ *.h5) 3C/2H Si polytype structure at 700 °C (Fig. 5B, right) 8_Ptype900_mesh.xdmf (+ *.h5) 3C/2H Si polytype structure at 900 °C (Fig. 5C, right) 9_Ptype1000_mesh.xdmf (+ *.h5) 3C/2H Si polytype structure at 1000 °C (Fig. 5D, right)