Electronic structural difference between Li7VN4 and Li7MnN4 due to the replacement of V with Mn: A simulation by a discrete variational Xα method

The difference in electronic structure of Li7MN4 (M=V and Mn) due to the replacement of V with Mn is studied by the discrete variational (DV) Xα method. Li7VN4 and Li7MnN4 crystallize in the same zinc-blende-like structure (space group: P-43n) with similar lattice constants of 9.6090 and 9.5548 Å, respectively. The DV-Xα calculations show that Li7VN4 is a semiconductor with energy gap between the empty V-3d related band and the completely occupied N-2p band, while Li7MnN4 has a metallic electron configuration because of the partially occupied Mn-3d related band located above the completely filled N-2p band, exhibiting the shift of the Fermi level caused by an increase in electron due to the replacement of V with Mn, where Mn (electron configuration: 3d54s2) owns two more 3d electrons than V (3d34s2) does. Electron paramagnetic resonance and magnetic susceptibility measurements reveal that Li7MnN4 is paramagnetic, resulting from the electrons partially occupying the Mn-3d related band, while Li7VN4 is diamagnetic, arising from the un-occupation of the V-3d related band. These experiments support the computational results.