Investigation of steps behavior on vicinal (111) surface during sublimation was carried out using 3D-model of diamond-like crystal. Step width periodic variations predicted by Schwoebel were found by modeling. Diamond-like crystal structure results in the asymmetry in atom fluxes to the upper or lower terraces, with the sign of asymmetry depending on the step structure. The essential effect of vacancies created on terraces on migration length of atoms was revealed.