Quantum Heisenberg model on a sawtooth-chain lattice: rotation-invariant Green’s function method

We apply the rotation-invariant Green’s function method (RGM) to study spin $$S=1/2$$ Heisenberg model on a one-dimensional sawtooth lattice, which has two nonequivalent sites in unit cell. check RGM predictions for observable quantities by comparison with exact-diagonalization and finite-temperature-Lanczos calculations. discuss thermodynamic dynamic properties of this relation mineral atacamite Cu $$_2$$ Cl(OH) $$_3$$ complementing outcomes results other approaches.