Related publications:
DFT+U and experiment fitted interatomic potentials for (U,Pu,Np)O2
Tiwary, van de Walle, Jeon and Gronbech-Jensen, Phys. Rev. B 2011.
DFT+U and experiment fitted interatomic potentials for UO2
Tiwary, van de Walle and Gronbech-Jensen, Phys. Rev. B 2009.
Modeling damaged materials requires force-fields that can accurately reproduce a wide variety of defect configurations and thermodynamics. We generated a range of such configurations using ab initio calculations. Furthermore, the materials here are complicated due to the presence of f-electrons - as such, plain density functional theory (DFT) does not apply here. We thus used sophisticated DFT+U calculations which corrects for some of the shortcomings of the mean field DFT approach.
We generated defect ground states as well as transition states using DFT+U and nudged elastic band (NEB) methods. These configurations as well as any available experimental data was then fit to classical force-fields.
Another novelty of these force-fields is that they include the stopping power correction relevant when atoms come close together. Most force-fields deal with the stopping power in an ad hoc fashion, often through arbitrary splining, which can lead to erroneous conclusions when modeling materials that have been damaged.