“…11). As expected, most of the plastic deformation for the model S4 is accommodate by prism (1-3) and basal (3)(4)(5)(6) systems whereas for the model S4Pa, prism (1-3), basal (4-6), and pyramidal <a> (7)(8)(9)(10)(11)(12)) are all active. The results presented in this paper for model S4Pa are for the case where the ratio of the CRSS for basal and prism slip systems is the same as that of model S4, however, we have tested other ratios, yet our conclusions did not change.…”