Molecular dynamics study of Hugoniot relation in shocked nickel single crystal

We study shock behavior of single crystalline nickel (Ni) using molecular dynamics (MD) simulations. Five different embedded-atom method (EAM) potential models were tested to select a suitable potential for shock simulation by comparing Grüneisen parameter, a key parameter in the equation of state describing energy change before and after shock load. We conducted shock propagation simulations along <100> direction of Ni and extracted (1) pressure-volume Hugoniot curve and (2) shock velocity (U_s) vs particle velocity (u_p) relation with selected potential models by Grüneisen parameter. Although the Hugoniot p-V curve calculated by the MD simulations is slightly higher than the experimental data, its trend is overall in good comparison, considering that the experimental data is obtained from polycrystalline Ni sample containing many internal defects. The Us-up curve shows deviation especially for low up, since the sound speed c₀ along <100> direction acts as the lower bound for shock velocity (U_s ≥ c₀).