Własności fizyczne i kwantowe przejścia fazowe w układach silnie skorelowanych elektronów w ramach ścisłej diagonalizacji połączonej z obliczeniami ab initio

We describe and implement the recently proposed approach combining exact dia- gonalization in the Fock space with an ab initio method (EDABI). Namely, we apply it to the description of correlated nanochains, fermionic ladders, and clus- ters. In particular, the microscopic parameters are determined and the evolu- tion of the system properties is traced in a systematic manner as a function of the interatomic distance. Both ground–state and dynamical correlation functions are discussed within a single scheme. The principal physical results of the the- sis are: (i) the appearance of the metallic and insulating features for a one– dimensional nanochain in the half–filled band case, (ii) the transformation from highly–conducting nanometal to the charge–ordered nanoinsulator away from the half–filling; (iii) an absolute stability of the hydrogen molecular clusters and lad- ders, and (iv) the molecule disintegration for the large densities; (v) the presence of the dielectric catastrophe for the fermionic ladder when the system crosses over from the band to the Mott–Hubbard insulating state. The analysis is performed us- ing the Gaussian 1s–like basis and includes long–range Coulomb interactions.