) The crystal structure of -Fe is bcc with a lattice parameter of a0 = 2.86. The self-diffusion of Fe occurs by the vacancy mechanism. The atomic definition of the diffusion coefficient is given by Di = giri 2i,eff where gi is a geometric factor, ri the elementary jump length and i,eff is the effective jump frequency. a) What is the elementary jump length in -Fe? b) If the effective jump frequency i,eff denotes the number of jumps per unit time to all surrounding neighboring lattice sites, what is the geometry factor gFe? c) If i,eff denotes the number of jumps per unit time to one distinct neighboring lattice sites, what is gFe?