First-principles study on δ-Pu surface stability

Abstract

δ-Pu has been widely used due to its outstanding material properties, and surface stability is essential for studying its surface corrosion mechanism. In this work, δ-Pu and its surface stability were analyzed based on first-principles calculations. The third-order Birch–Murnaghan equation of state fitted the calculated data for the δ-Pu cell, and the lattice constant of equilibrium structure was obtained. By constructing the surface models of three conventional crystal directions, (100), (110), and (111), the surface structure was optimized based upon the Quasi-Newton method, and the surface energy and electronic structure were calculated. The results show that the (110) surface energy of δ-Pu was 0.103 eV/Å2, and the (111) surface energy of δ-Pu was 0.052 eV/Å2. Thus, the d-band center of the (111) plane is farther away from the Fermi level than (100) and (110). Among the three typical crystal orientation planes, the surface energy and electronic structure show that the (111) plane was the most stable crystal orientation plane of δ-Pu.