Two-site Hubbard dimer
= Two-site Hubbard dimer
Two localized orbitals coupled by hopping, with an on-site penalty for <double occupancy>. At two-electron filling the competition between hopping and local repulsion can be solved exactly within the finite basis. It gives a compact example of a molecular bonding crossover and <electron correlation>; it is not by itself a complete real-molecule binding curve.