M. Cardenas et al., EXACT AND ADIABATIC SOLUTIONS FOR A SPINLESS PEIERLS-HUBBARD MODEL INA FINITE CLUSTER, Physical review. B, Condensed matter, 48(15), 1993, pp. 10719-10727
The exact solution of the Hubbard-Peierls model is given in a cluster
of six atoms and three spinless electrons. Phonons with wave vector k
= pi are retained and quantum mechanically analyzed. Energy level and
several averages are evaluated, thus determining the physical properti
es of the model in terms of the parameters of the system. The regime o
f the distorted lattice is obtained. The exact and Born-Oppenheimer (B
O) results are compared, concluding that the BO enhances quantum fluct
uations; this peculiar behavior is explained.