High pressure theoretical studies of actinide dioxides

Actinide dioxides (ThO2, UO2, Pu-2 etc.) compounds have the CaF2-type structure at ambient pressure and temperature. Under high pressure, they exist in the PbCl2-type structure, belonging to space group Pnma [1]. We have studied crystal structures under high pressure in actinide dioxides by means of first-principles self-consistent total-energy calculations with the non-local Perdew, Burke and Ernzerhof (PBE) exchange correlation using the full-potential linear-muffin-tin-orbital (FPLMTO) method. The atomic equilibrium volume, bulk modulus and transition pressure for actinide dioxides were calculated, covering the full pressure range for which the mentioned experiments have been done [2].