Fig. 2: Two-dimensional partially flat bands and quasi-compact localized states.
From: Quasi-localization and Wannier obstruction in partially flat bands
a The lattice and hopping structures of the 3D nodal line semimetal model. At each site, two orbitals, denoted by A and B, reside. Lines with red, blue, and yellow colors represent hopping processes. Solid and dashed lines indicate + and − signs of the hopping amplitudes. (b) The band structure for kz = 0. The nodal ring is denoted by the red closed curve. (c) A schematic view of the quasi-compact localized state(Q-CLS) of the nodal line semimetal in the semi-infinite system. (d) A linear combination of Q-CLSs in (c) with different apex positions, resulting in a Bloch wave function.
