Heisenberg exchange H = −J·Σ S_i·S_j on spin-commutator algebra with Jacobi identity

Heisenberg exchange Hamiltonian on the spin-commutator Lie algebra. Setup: localised spin-s operators S_i^a (a = x, y, z) on lattice sites i, with canonical commutation [S_i^a, S_j^b] = iℏ·δ_ij·ε^{abc}·S_i^c (SU(2) Lie algebra structure).…