K. Rosciszewski, ON A SIMPLE CEPA LIKE APPROACH TO ELECTRON CORRELATIONS IN D-DIMENSIONAL HUBBARD-MODEL CLUSTERS, ACT PHY P B, 28(9), 1997, pp. 2049-2055
In this short note a simple quantum chemical type of approach to elect
ron correlations in d-dimensional Hubbard model is proposed. In essenc
e, the method is very closely related to CEPA-0 approximation (also to
Gutzwiller approximation and to the Local ansatz) and as such is no n
ovelty. The real aim is to provide unsophisticated and computationally
cheap method which allows for an easy treatment of electron correlati
ons in finite cluster models with a simple Hubbard type Hamiltonians.