Fig. 1: Band selective renormalization and molecular nature of monolayer Nb₃Cl₈.

a The density plot of the density functional theory (DFT) electronic structure shows several nearly flat bands around the Fermi level (E_F), while those bands at higher binding energies are more dispersive. \({\epsilon }_{i}^{cal}\) with i ∈ [1, 4] are the binding energy of the flat bands in DFT calculations. \({\epsilon }_{i}^{exp}\) with i ∈ [1, 3] denote the location of the first three bands detected in angle-resolved photoemission spectroscopy. Here DOS refers to the density of states. b Molecular orbitals of the flat bands \({\epsilon }_{i}^{cal}\) which potentially induce a quantum spin liquid state with effective spin-1/2 Nb-trimer organized in effective triangular lattice.