Crucial parameters for simulations + additional comments/information: - units: metal - atom_style atomic - lattice parameter: 2.855 - Sample-measures: ~180, ~180, ~720 Angström - boundary-conditions: relax: p p p; shock & recovery: p p s - min_styles: fire and cg - timestep: 0.001 - temp/rescale with 1 and 700 K - piston-velocites: 0.5 km/S, 0.8 km/s, 1.6 km/s - dump-files from relaxation used for shock, restart-files from shock simulation used for recovery - compute: pe/atom Caption Fig. 1: Snapshots of the shock compression process at 0 (inital stage), 3, 6, and 9 ps, respectively. The sample has 32 grains and is compressed with an accelerated piston at a velocity of 1.6 km/s. The piston itself is visible as a small layer of atoms on the bottom of the sample. Green is fcc, red is hcp, blue is bcc, and gray is other structures. Caption Fig. 2: Snapshots of the sample with 16 grains at 0.5 (a), 0.8 (b), and 1.6 km/s (c). The structures are identified with OVITO using PTM. Green is fcc, red is hcp, blue is bcc, and gray is other structures. The shock wave propagated from bottom to top. Caption Fig. 3: Snapshots of the sample with 32 grains at 0.5 (a), 0.8 (b), and 1.6 km/s (c). The structures are identified with OVITO using PTM. Green is fcc, red is hcp, blue is bcc, and gray is other structures. The shock wave propagated from bottom to top. Caption Fig. 4: Snapshots of the sample with 64 grains at 0.5 (a), 0.8 (b), and 1.6 km/s (c). The structures are identified with OVITO using PTM. Green is fcc, red is hcp, blue is bcc, and gray is other structures. The shock wave propagated from bottom to top. Caption Fig. 5: Spatial profiles of the atom velocity in the z direction, vz , the pressure components parallel to the shock wave propagation direction, Pzz , and the shear stress for the sample with 16 grains for several piston velocities: 0.5 (a), 0.8 (b), and 1.6 km/s (c). Caption Fig. 6: Spatial profiles of the atom velocity in the z direction, vz , the pressure components parallel to the shock wave propagation direction, Pzz , and the shear stress for the sample with 32 grains for several piston velocities: 0.5 (a), 0.8 (b), 1.6 km/s (c). Caption Fig. 7: Spatial profiles of the atom velocity in the z direction, vz , the pressure components parallel to the shock wave propagation direction, Pzz , and the shear stress for the sample with 64 grains for several piston velocities: 0.5 (a), 0.8 (b), 1.6 km/s (c). Caption Table I: Different nanocrystal samples at 24 ps for 0.5 km/s, 22 ps for 0.8 km/s and 19 ps for 1.6 km/s and their Pzz values (spall strength) depending on grain number. Beginning of failure occurred at the given points in time. Caption Table II: Different shock wave velocities (SWVs) depending on grain numbers and shock velocity of the piston itself. Additional Information in regards to SWV (table II): The data extracted from the dump files using OVITO didn't account for the compression during the shock simulation.  Therefore, we had to take into account the shift of the coordinate system. The following values have to be added to the 5 and 9 ps points in time to get the results we calculated in our paper: 16 grains: 0.5 km/s - 5 ps: 24,502492 Angström 0.5 km/s - 9 ps: 44,502492 Angström 0.8 km/s - 5 ps: 39,203992 Angström 0.8 km/s - 9 ps: 71,203992 Angström 1.6 km/s - 5 ps: 78,407992 Angström 1.6 km/s - 9 ps: 142,408092 Angström 32 grains: 0.5 km/s - 5 ps: 24,502484 Angström 0.5 km/s - 9 ps: 44,502484 Angström 0.8 km/s - 5 ps: 39,203984 Angström 0.8 km/s - 9 ps: 72,203984 Angström 1.6 km/s - 5 ps: 78,407984 Angström 1.6 km/s - 9 ps: 142,408084 Angström 64 grains: 0.5 km/s - 5 ps: 24,502518 Angström 0.5 km/s - 9 ps: 44,502518 Angström 0.8 km/s - 5 ps: 39,20402 Angström 0.8 km/s - 9 ps: 71,20402 Angström 1.6 km/s - 5 ps: 78,40802 Angström 1.6 km/s - 9 ps: 142,40782 Angström