For quantum mechanical reasons (see exchange interaction or Magnetism § Quantum-mechanical origin of magnetism), the dominant coupling between two dipoles may cause nearest-neighbors to have lowest energy … See more

The integrability is underpinned by the existence of large symmetry algebras for the different models. For the XXX case this is the Yangian $${\displaystyle Y({\mathfrak {sl}}_{2})}$$, while in the XXZ case this is the quantum group
These appear … See more

XXX1/2 model
Following the approach of Ludwig Faddeev (1996), the spectrum of the Hamiltonian for the … See more

• Another important object is entanglement entropy. One way to describe it is to subdivide the unique ground state into a block (several … See more

• Classical Heisenberg model
• DMRG of the Heisenberg model
• Quantum rotor model
• t-J model
• J1 J2 model See more