For quantum mechanical reasons (see exchange interaction or Magnetism § Quantum-mechanical origin of magnetism), the dominant coupling between two dipoles may cause … 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 $${\displaystyle Y({\mathfrak {sl}}_{2})}$$, … See more

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

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