An effective and reliable Finnis-Sinclair (FS) type potential is developed for large-scale molecular dynamics (MD) simulations of plasticity and phase transition of magnesium (Mg) single crystals under high-pressure shock loading. The shock-wave profiles exhibit a split elastic-inelastic wave in the [0001](HCP) shock orientation and a three-wave structure in the [10-10](HCP) and [-12-10](HCP) directions, namely, an elastic precursor, a followed plastic front, and a phase-transition front. The shock Hugoniot of the particle velocity (U (p)) vs the shock velocity (U (s)) of Mg single crystals in...