Title: The first-principles treatment of the electron-correlation and spin-orbital effects in uranium mononitride nuclear fuels
Citation: PHYSICAL CHEMISTRY CHEMICAL PHYSICS vol. 14 no. 13 p. 4482–4490
Publication Year: 2011
JRC N°: JRC68223
ISSN: 1463-9076
URI: http://pubs.rsc.org/en/content/articlelanding/2012/CP/C2CP40297A
DOI: 10.1039/c2cp40297a
Type: Articles in periodicals and books
Abstract: The DFT+U calculations were employed in a detailed study of the strong electron correlation effects in promising nuclear fuel -- uranium mononitride (UN). A simple method for solving the multiple minima problem in DFT+U simulations and insure obtaining the correct ground state is suggested and applied. The crucial role of spin-orbit interactions in reproduction of the U atom total magnetic moment is demonstrated. Basic material properties (the lattice constants, the spin- and total magnetic moments on U atoms, magnetic ordering, and the density of states) were calculated varying the Hubbard U-parameter. Varying the tetragonal unit cell distortion, the meta-stable states have been carefully identified and analyzed. The difference of the magnetic and structural properties obtained for the meta-stable and ground states are discussed. The optimal effective Hubbard parameter Ueff =1.85 eV reproduces correctly the UN anti-ferromagnetic ordering, and only slightly overestimates the experimental total magnetic moment of U atom and the unit cell volume.
JRC Directorate:Nuclear Safety and Security

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