First principles investigation of electron correlation and Lifshitz transition within iron polynitrides

Metal poly-nitrogen compounds are gaining great interests as potential high energy density materials. Several iron polynitrides have been recently synthesized and investigated under high pressure (2018Nature Communications92756). In this work the electron correlations within these iron poly-nitrogen compounds were self-consistently determined, benchmarked with those obtained from linear response approach. Along with the increase of the concentration of nitrogen, the Coulomb interaction strengths show a monotonic decrease, where FeN and FeN(2)are antiferromagnetic and the others are ferromagnetic. Then the electron correlation is studied along with the pressure, where the electrons are more delocalized as pressure becomes higher. One electronic topological transition was found for FeN2, owing to a breaking of symmetry of spin and a transition of magnetism induced by a structural change. The band structure, densities of states, Fermi surface and absorption spectra were calculated and discussed.

Automated summary

In this work, electron correlations within iron poly-nitrogen compounds were investigated as a function of nitrogen concentration and pressure. The Coulomb interaction strengths decreased monotonically with increasing nitrogen concentration, while electrons became more delocalized as pressure increased. A unique electronic topological transition was found for FeN2, with a breaking of spin symmetry and transition of magnetism induced by a structural change. Additionally, band structure, densities of states, Fermi surface, and absorption spectra were calculated and discussed.