= 0 plane with an in-plane bandwidth of only 4 meV, located just 0.06 eV above the true conduction-band minimum. Real-space analysis and effective bond-centered lattices reveal a connectivity-controlled mechanism for dispersion suppression. Moreover, very small strains can directly tune this low-lying flat band into the true conduction-band minimum while preserving weak dispersion, enhancing its experimental relevance. Our results establish bonding topology as a promising route to flat-band engineering in light-element covalent frameworks beyond conventional interference-based scenarios.
Chen et al. (Mon,) studied this question.