Abstract
Using first-principles density-functional theory, we calculate the bond strengths between the 12 nearest neighbors in plutonium for both pure Pu and a Pu-3.7 at. % Ga alloy. Our results for pure Pu reveal a structure with the monoclinic space group rather than face-centered cubic , showing that the anomalously large anisotropy of plutonium is a consequence of greatly varying bond strengths between the 12 nearest neighbors. Further results for a Pu-3.7 at. % Ga alloy show that the nearest-neighbor bond strengths around a Ga atom are more uniform. Hence, our calculations address (i) why the ground state of Pu is monoclinic, (ii) why distortions of the phase are viable, with considerable implications for the behavior of the material as it ages due to anisotropic response to self-irradiation, and (iii) why Ga stabilizes face-centered cubic -Pu.
- Received 27 September 2005
DOI:https://doi.org/10.1103/PhysRevLett.96.206402
©2006 American Physical Society