**Appendix B. Extended Cutting Length**

It might be speculated that a cutting length of *L* = 100 Å is not sufficient to obtain steady-state cutting conditions, in particular for the negative rake angles. We therefore increased the cutting length in these cases to 200 Å. The evolution of the cutting force and of the thrust force shown in Figure A3 demonstrated that the simulation results indeed stabilized at *L* = 100 Å. The data for cutting lengths between 100 and 200 Å showed, apart from fluctuations caused by the discontinuous emission of dislocations, the same average behavior. We assemble the averages over the last 100 Å in these extended runs in Table 1, which shows that deviations of ≤ 10 % showed up between the 100 Å run and the new extended run. As a consequence, also the friction angle and the force angle showed only minor deviations from the shorter run, cf. Figure 8, and the conclusions stated in the main part of the text remain valid.

**Figure A3.** (**a**) Cutting force, *Fc*, and (**b**) thrust force, *Ft*, as a function of the cutting length *L* for an extended simulation up to 200 Å for the negative rake angles, *α* = −22.5◦ and −45◦.

The chip shapes also (Figure A4) showed no new features compared to the shorter runs shown in Figure 5. In particular, for the most negative rake angle of *α* = −45◦, no chip was formed on the top surface. The chip for the *α* = −22.5◦ rake angle grew in size, but its structure consisting of several sub-peaks remained intact. Note that the very first peak (close to the rake face), which was created by the glide of 1/2[111] dislocations, retained its identity. Its width did not change (see Table 1), which indicated that this feature did not change any more after *L* = 100 Å, in close agreement with the result obtained after cutting of 100 Å. Our conclusion that the chip thickness fits again nicely with the theoretical prediction, Equation (4), was hence unchanged.

**Figure A4.** Side views of the chips formed during cutting for an extended simulation up to 200 Å for the negative rake angles, *α* = −22.5◦ and −45◦.

Finally, we display in Figure A5 the dislocations generated after cutting the crystals for the extended cutting length of *L* = 200 Å. For the rake angle of *α* = −22.5◦, again, the large number of [1¯1¯1] partials dominated the picture; these were responsible for the substructure of the chip containing several peaks. Indeed, when comparing Figure A5a with Figure 3, a new dislocation emission center at the chip front emerged, which induced a new peak at the front of the chip. For the rake angle of *<sup>α</sup>* <sup>=</sup> <sup>−</sup>45◦, dislocation emission in [1¯1¯1¯] directions proceeded and was responsible for the increased deformation of the frontal (right-hand side) surface, which now extended almost over the entire simulated crystal face in the [1¯1¯0] direction. The tangle of dislocations beneath the front part of the tool increased under extended cutting. Due to dislocation reactions, for both rake angles shown in Figure A5, vacancies were created, which are visualized as small yellow spheres.

**Figure A5.** As in Figure 2, but for an extended cutting length, *L* = 200 Å. Snapshots are for a rake angle of (**a**) *α* = −22.5◦ and of (**b**) −45◦.

We concluded that after increasing the cutting length from *L* = 100 to 200 Å, the dislocation generation proceeded in analogy to the shorter cutting length, and no qualitatively new features showed up.
