Atomistic modeling of high-speed deformation by compression of ideal, defective (5% vacancies, 5% impurity hydrogen atoms) magnesium nanocrystals with "hard" and "soft" orientations at T = 300 – 375 K was carried out. Three interatomic interaction potentials were used. The evolution of the microrelief of the free surface of magnesium nanocrystals in the process of plastic flow is shown. Diagrams "stress σ – deformation ε" are constructed, deformation dependences of the scalar dislocation density are determined, and the strain rate dependences on the degree of deformation ε are constructed. The influence of vacancies and hydrogen atoms on the shape of deformation curves, dislocation structure and scalar dislocation density is shown. Evolution of typical dislocation structures is shown, some typical dislocation reactions are given. Conclusions are drawn on the influence of the type of interatomic interaction potential on the calculated characteristics.