Ground state phase diagram of extended attractive Hubbard model

The ground state phase diagram of the weakly coupled extended Hubbard model with intraatomic attraction has been derived with the Hartree theory formulated in terms of the Bogoliubov variational approach. For a given value of electron density, the nature of the ordered ground state depends essentially on the sign and the strength of the nearest neighbor coupling. Some features are similar to those in the strong coupling limit obtained earlier.