The discovery of new materials with properties dominated by strong correlations among electrons h... more The discovery of new materials with properties dominated by strong correlations among electrons has opened the problem of new appropriate calculation schemes. In the case of 1D models the Bethe ansatz provides an exact evaluation of many relevant physical quantities, but not a complete framework. By way of developing new methods appropriate to strongly correlated systems, we study the 1D Hubbard model by means of the Composite Operator Method. We investigate various local quantities. A comparison with exact results and other analytical approaches show a reasonable agreement and determine the applicability range of our approximate scheme.
Strongly correlated electron systems with planar structure, like high-% T_{c} superconductors, ar... more Strongly correlated electron systems with planar structure, like high-% T_{c} superconductors, are currently under intensive study. In the search for a realistic model to describe the anomalous behaviors of these systems, we have studied the 2D Extended Hubbard model by means of the Composite Operator Method. The local properties, the density of states and the Fermi surface have been calculated as functions of the model parameters. Particular attention has been paid to the role played by the intersite interaction V which drives important changes in the electronic properties of the system.
We study the spin-32 Hubbard–Kondo lattice model by means of the Composite Operator Method, after... more We study the spin-32 Hubbard–Kondo lattice model by means of the Composite Operator Method, after applying a Holstein–Primakov transformation. The spin and particle dynamics in the ferromagnetic state are calculated by taking into account strong on-site correlations ...
The electronic states of the two-dimensional Hubbard model are investigated by means of a 4-pole ... more The electronic states of the two-dimensional Hubbard model are investigated by means of a 4-pole approximation within the Composite Operator Method. In addition to the conventional Hubbard operators, we consider other two operators which come from the hierarchy of the ...
This book contains lectures on strongly correlated electron systems presented by eminent physicis... more This book contains lectures on strongly correlated electron systems presented by eminent physicists. These lectures are up-to-date summaries of relevant subjects in the field of condensed matter physics. Contributions include: BCS theory of nodal superconductors; strongly correlated particle systems and composite operator methods; diagonalization- and numerical renormalization-group-based methods for interacting quantum systems; as well as phenomenological aspects of unconventional superconductivity.
The discovery of new materials with properties dominated by strong correlations among electrons h... more The discovery of new materials with properties dominated by strong correlations among electrons has opened the problem of new appropriate calculation schemes. In the case of 1D models the Bethe ansatz provides an exact evaluation of many relevant physical quantities, but not a complete framework. By way of developing new methods appropriate to strongly correlated systems, we study the 1D Hubbard model by means of the Composite Operator Method. We investigate various local quantities. A comparison with exact results and other analytical approaches show a reasonable agreement and determine the applicability range of our approximate scheme.
Strongly correlated electron systems with planar structure, like high-% T_{c} superconductors, ar... more Strongly correlated electron systems with planar structure, like high-% T_{c} superconductors, are currently under intensive study. In the search for a realistic model to describe the anomalous behaviors of these systems, we have studied the 2D Extended Hubbard model by means of the Composite Operator Method. The local properties, the density of states and the Fermi surface have been calculated as functions of the model parameters. Particular attention has been paid to the role played by the intersite interaction V which drives important changes in the electronic properties of the system.
We study the spin-32 Hubbard–Kondo lattice model by means of the Composite Operator Method, after... more We study the spin-32 Hubbard–Kondo lattice model by means of the Composite Operator Method, after applying a Holstein–Primakov transformation. The spin and particle dynamics in the ferromagnetic state are calculated by taking into account strong on-site correlations ...
The electronic states of the two-dimensional Hubbard model are investigated by means of a 4-pole ... more The electronic states of the two-dimensional Hubbard model are investigated by means of a 4-pole approximation within the Composite Operator Method. In addition to the conventional Hubbard operators, we consider other two operators which come from the hierarchy of the ...
This book contains lectures on strongly correlated electron systems presented by eminent physicis... more This book contains lectures on strongly correlated electron systems presented by eminent physicists. These lectures are up-to-date summaries of relevant subjects in the field of condensed matter physics. Contributions include: BCS theory of nodal superconductors; strongly correlated particle systems and composite operator methods; diagonalization- and numerical renormalization-group-based methods for interacting quantum systems; as well as phenomenological aspects of unconventional superconductivity.
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