Phonon spectra of plutonium at high temperatures
Abstract
Ab initio molecular dynamics calculations are used to investigate the vibrational properties of the high-temperature δ and ɛ phases of plutonium. We combine the local-density approximation (LDA)+U for strong electron correlations and the temperature-dependent effective potential method in order to calculate the phonon spectra of the two phases, as well as their dependence on temperature. Our results show that the ɛ phase can only be stabilized when temperature and correlations are simultaneously accounted for. We are also able to quantify the degree of anharmonicity of the two phases. While the δ phase is fairly harmonic up to 1000 K, we find that the ɛ phase is strongly anharmonic, which explains why this structure dominates the phase diagram at high temperature.
- Publication:
-
Physical Review B
- Pub Date:
- March 2017
- DOI:
- 10.1103/PhysRevB.95.104303
- Bibcode:
- 2017PhRvB..95j4303D