US EPA

3701917 

Journal Article 

GGA plus U study of uranium mononitride: A comparison of the U-ramping and occupation matrix schemes and incorporation energies of fission products 

Claisse, A; Klipfel, M; Lindbom, N; Freyss, M; Olsson, Par 

2016 

Yes 

Journal of Nuclear Materials
ISSN: 0022-3115 

478 

119-124 

10.1016/j.jnucmat.2016.06.007 

WOS:000381644500015 

Uranium mononitride is studied in the DFT + U framework. Its ground state is investigated and a study of the incorporation of diverse fission products in the crystal is conducted. The U-ramping and occupation matrix control (OMC) schemes are used to eliminate metastable states. Beyond a certain amount of introduced correlation, the OMC scheme starts to find a lower total energy. The OMC scheme is chosen for the second part of this study. Furthermore, the influence of the magnetic ordering is studied using the U-ramping method, showing that antiferromagnetic order is the most stable one when the U parameter is larger than 1.75 eV. The effect on the density of states is investigated and elastic constants are provided for comparison with other methods and experiments. The incorporation energies of fission products in different defect configurations are calculated and these energies are corrected to take into account the limited size of the supercell. (C) 2016 Elsevier B.V. All rights reserved.