Effect of the phonon and magnetic anharmonicity on the thermal and elastic properties of nearly magnetic δ-plutonium

Abstract

The temperature dependences of the total heat capacity and the lattice components of the bulk modulus, the volume thermal expansion coefficient, and the mean-square deviation of atoms from the equilibrium positions of nearly magnetic δ-plutonium (using the Pu_0.96Ga_0.04 alloy as an example) have been calculated within the framework of the self-consistent thermodynamic model. The electronic heat capacity has been calculated using the results obtained in terms of the self-consistent spin-fluctuation theory based on the inclusion of the strong magnetic anharmonicity, which leads to a splitting of the electronic spectra by fluctuating exchange fields. On this basis, the effect of phonon anharmonicity not only on the lattice heat capacity but also on other thermal and elastic properties has been considered.