The atomistic simulation of pressure-induced phase transition in uranium mononitride

Phase transition in uranium mononitride (UN) at high pressure has been studied using molecular dynamics. At low pressure, UN has the cubic structure like NaCl (with the space group Fm3m). The research based on Gibbs energy calculation shows that cubic UN turns into rhombohedral face-centered structure (with the space group R (3) over barm) at pressure about 32 GPa. It is shown that parameters of R (3) over barm-structure change at increasing of the pressure. At various pressures, the parameters of structures with isotropic stress tensor are different.