P. Söderlind, J. Klepeis, A. Landa, B. Sadigh, F. Zhou, R. Hood, A. McMahan, D. Orlikowski, J. Pask, and Lin Yang and John Moriarty

Methods: FP-LMTO, EMTO, MGPT, DMFT, LAPW and PW.

Collaborators: High-Pressure Physics Group (LLNL), Richard Scalettar (UC Davis), Levente Vitos (KTH, Stockholm), Alexander Lichtenstein (University of Hamburg, Germany)

**Elastic constants for plutonium metal** |

**Phase** | **C11** | **C22** | **C33** | **C44** | **C55** | **C66** | **C12** | **C13** | **C23** | **C15** | **C25** | **C35** | **C46** |

**α** | 120 | 109 | 86.2 | 43.4 | 50.6 | 43.7 | -9.3 | 1.1 | -11.5 | 22.1 | 20.2 | 21.9 | -0.25 |

**β** | 75.4 | 64.4 | 65.1 | 32.2 | 22.4 | 27.2 | 27.0 | 20.6 | 23.1 | 20.6 | 21.5 | 19.4 | -0.95 |

**γ** | 81.0 | 63.7 | 70.5 | 21.6 | 11.9 | 21.7 | 31.5 | 22.6 | 22.6 | | | | |

**δ** | 65.0 | | | 38.0 | | | 29.0 | | | | | | |

**δ′** | 64.7 | | 62.0 | 42.1 | | 42.2 | 43.2 | 29.6 | | | | | |

Calculated elastic constants for alpha, beta, gamma, delta, and delta' plutonium

Predicting the properties of f-electron metals represents a fundamental challenge in condensed matter physics. Their complex geometries, narrow f-bands, and extraordinary heavy nuclei require a highly accurate numerical treatment. Also, correlation effects of the f-electrons impose a special challenge to theoreticians in some regimes. Our goal is the development of accurate multiphase equations of state, phase diagrams, and melt curves for f-electron materials. The primary theoretical tools are temperature-dependent PW, FP-LMTO, LAPW, and EMTO electronic structure calculations, and many-body and angular-force MGPT atomistic simulations, while dynamical mean-field theory is used where correlation effects are particularly significant. Results to date include temperature-dependent FP-LMTO calculations of the equations-of-state, structural stability, elastic moduli, zone-boundary phonons, unrelaxed vacancy formation energies, and ideal shear strengths. DMFT has also been successfully applied to the correlation-driven alpha-to-gamma transition in Ce. We have worked closely with CMMD diamond-anvil-cell experimentalists. This research effort is also closely coupled to the ongoing study of high-pressure strength. In particular, the phase diagram and elastic moduli are crucial inputs for full multi-phase strength models.

### Recent Publications

- A. Migliori, P. SÃ¶derlind, A. Landa, F. J. Freibert, B. Maiorov, B. J. Ramshaw, and J. B. Betts, "Origin of the multiple configurations that drive the response of delta-plutonium's elastic moduli to temperature",
*Proceedings of the National Academy of Sciences of the U.S.A.*, 113, 11158 (2016). - P. Söderlind, F. Zhou, A. Landa, and J. E. Klepeis, "Phonon and Magentic Structure in delta-Plutonium from Density-Functional Theory", Sci. Rep.
**5**, 15958 (2015) - P. Söderlind, P. E. A. Turchi, A. Landa, and V. Lordi, "Ground-state properties of Rear-Earth Metals: and Evaluation of Density-Functional Theory", J. Phys.: Condens. Mat.
**26**, 416001 (2014). - P. Söderlind and A. Landa, "Theoretical Confirmation of Ga-Stabilized Anti-Ferromagnetism in Plutonium Metal", J. Nucl. Mater.
**448**, 310 (2014). - A. Landa, P. Söderlind, and P. E. A. Turchi, "Density-functional Study of U-Mo, Np-Mo, Pu-Mo, and Am-Mo Alloys", J. Nucl. Mat
**434**, 31 (2013). - J. R. Jeffries, P. Söderlind, H. Cynn, A. Landa, W. J. Evans, S.T. Weir, Y. K. Vohra, and G. Lander, "Magnetism and Structural Distortions in Uranium Sulfide Under Pressure", Phys. Rev, B
**87**, 214104 (2013). - P. Söderlind, K. T. Moore, A. Landa, B. Sadigh, and J. A. Bradley, "Pressure-Induced Changes in the Electronic Structure of Americium Metal", Phys. Rev. B
**84**, 075138 (2011). - A. Landa, P. Söderlind, and P. E. A. Turchi, "Density-Functional Study of U-Mo and U-Zr Alloys", J. Nucl. Mater.
**414**, 132 (2011). - E. Gorelov, J. Kolorenc, T. Wehling, H. Hafermann, A. B. Shick, A. N. Rubtsov, A. Landa, A. K. McMahan, V. I. Anisimov, M. I. Katsnelson, and A. I. Lichtenstein, "Importance of Full Coulomb Interactions for Understanding the Electronic Structure of delta-Pu ", Phys. Rev. B
**82**, 085117 (2010). - P. Söderlind, A. Landa, J.E. Klepeis, Y. Suzuki, and A. Migliori, "Elastic Properties of Pu Metal and Pu-Ga Alloys, ", Phys. Rev. B
**81**, 224110 (2010). - P. Söderlind and J. E. Klepeis, "First-principles elastic properties of alpha-Pu, ", Phys. Rev. B
**79**, 104110 (2009). - A. Landa, P. Söderlind, and P.E.A. Turchi, "Density-Functional Study of the U-Zr System, ", J. Alloys Compd.
**478**, 103 (2009). - P. Söderlind, "Quantifying the importance of orbital over spin correlations in delta-Pu within density-functional theory ," Phys. Rev. B
**77**, 085101 (2008). - L.H. Yang, R.Q. Hood, J.E. Pask, and J.E. Klepeis, "Large-scale quantum mechanical simulations of high-Z metals," J. Computer-Aided Mater. Des.
**14**, 337 (2007). - J.-X Zhu, A. K. McMahan, M. D. Jones, T. Durakiewicz, J. J. Joyce, J. M. Wills, and R. C. Albers, "Spectral Properties of delta-Plutonium: Sensitivity to 5f Occupancy, ", Phys Rev. B.
**76**, 245118 (2007). - A. Landa, P. Söderlind, and L. Vitos, "Density-functional calculations of alpha-Pu-Ga(Al) alloys ," J. Alloys Compd.
**444-445** 296 (2007) - K. T. Moore, G. van Lann, R. G. Haire, M. A. Wall, A. J. Schwartz, and P. Söderlind, "Emergence of Strong Exchange Interaction in the actinide series: The driving force for magnetic stabilization in Curium ", Phys. Rev. Lett.
**98**, 236402 (2007). - K. T. Moore, P. Söderlind, A. J. Schwartz, and D. E. Laughlin, "Symmetry and Stability of delta Plutonium: The Influence of Electronic Structure ," Phys. Rev. Lett.
**96**, 206402 (2006). - P. Söderlind and A. Landa, "Crystal Stability and Equation of State for Americium: Theory, ", Phys. Rev. B
**72** 024109 (2005). - A. Landa, P. Söderlind, A. Ruban, L. Vitos, and L. Pourovskii, "First-Principles Phase Diagram of the Ce-Th System, ", Phys. Rev. B
**70** 224210 (2004). - P. Söderlind and B. Sadigh, "Density-functional calculations of alpha, beta, gamma, delta, delta', and epsilon plutonium ," Phys. Rev. Lett.
**92**, 185702 (2004). - A. Landa, P. Söderlind, and A. Ruban, "Monte Carlo Simulations of the Stability of delta-Pu," J. Phys.: Condens. Mat.
**15**, (2003) L371. - P. Söderlind, A. Landa and B. Sadigh, "Density-functional investigation of magnetism in delta-Pu ," Phys. Rev. B
**66**, 205109 (2002). - P. Söderlind, "Ambient pressure phase diagram of plutonium: a unified theory for alpha-Pu and delta-Pu ," Europhys. Lett.
**55**, 525 (2001). - P. Söderlind, "Theory of the crystal structures of cerium and the light actinides ," Adv. Phys.
**47**, 959 (1998).

Maintained by Lorin X. Benedict