Density-functional investigation of magnetism in δ-Pu -: art. no. 205109

We present density-functional results of delta-Pu obtained from three electronic-structure methods. These methods have their individual strengths and are used in combination to investigate the magnetic and crystal stability of delta-Pu. An all-electron, full potential linear muffin-tin orbitals (FPLMTO) method, that includes corrections for spin-orbit coupling and orbital-polarization effects, predicts delta-Pu to be an antiferromagnet at zero temperature with a volume and a bulk modulus in very good agreement with experiment. The site-projected magnetic moment is smaller than expected (similar to1.5 mu(B)) due to large cancellation of spin and orbital moments. These calculations also predict a mechanical instability of antiferromagnetic (AF) delta-Pu. In addition, techniques based on the Korringa-Kohn-Rostoker (KKR) method within a Green's-function formalism and a projector augmented wave (PAW) method predict the same behavior of delta-Pu. In order to study disordered magnetism in delta-Pu, the KKR Green's-function technique was used in conjunction with the disordered local-moment model, whereas for the FPLMTO and PAW methods this was accomplished within the special quasirandom structure model. While AF delta-Pu remains mechanically unstable at lower temperatures, paramagnetic delta-Pu is stabilized at higher temperatures where disordered magnetic moments are present and responsible for the crystal structure, the low density, and the low bulk modulus of this phase.