Uranium mono-nitride (UN) and its alloying nitride such as UxZr1-xN have received significant attention due to the potential usage as a high-temperature nuclear fuel in the Generation-IV reactors. These nitrides have the following advantages: enhanced safety and minimal production of nuclear waste, use present nuclear waste as fuel, burn thorium and minor actinides, excellent thermal conductivity, high metal density, good compatibility with the sodium coolant.
So far, despite many theoretical studies have been carried out to understand the magnetic properties, one-particle DFT cannot fulfill the underlying physics of these materials. Hence, we go beyond DFT and establish a model of dynamical mean-field theory (DMFT) to study the electronic structure and particularly the band dispersion relation, as well as the magnetic properties. From our preliminary results, the Fermi-liquid behavior has been observed in these materials, so that we will use the developed model to step forward to provide a deep understanding of UN and UxZr1-xN. On the other hand, allying Zr to UN have shown better performance under the iridizations, but the concentration and temperature dependent properties are still unclear. The coherent potential approximation (CPA) will be employed to study to the randomly distributed Zr, U atoms the free energies with the consideration of magnetic and configurational entropy.
An accurate ab initio-based description of electronic structure, thermodynamic, kinetic, and magnetic properties of complex multicomponent systems with non-trivial electronic interactions is an extremely complicated issue, and need for large computer resources.