Energy dispersion of electrons is the most fundamental property of the solid state physics. In models of electrons on a lattice with strong geometric frustration, the band dispersion of electrons can disappear due to the quantum destructive interference of the wavefunction. This is called a flat band, and it is known to be the stage for the emergence of various fascinating physical properties. It is a challenging task to realize this flat band in a real material. In this study, we performed first-principles calculations on two compounds, Pb2As2O7 and Pb2Sn2O7, which are candidates to have flat bands near the Fermi level. For Pb2As2O7, similar to the previously calculated Pb2Sb2O7, nearly flat bands were confirmed. In the case of Pb2Sn2O7, a complex band structure was observed; nevertheless, bands with minimal energy dispersion near the Fermi level were identified. These findings underscore the importance of investigating the influence of flat bands on electronic energy dispersion, providing a crucial step toward understanding the emergence and characteristics of flat bands in novel materials.
PACS numbers: 71.20.Nr, 71.20.-b, 75.47.Lx