Related papers: Effective t-J Hamiltonian for the Copper Oxides
The t-J model with constant t and J between any pair of sites is studied by exploiting the symmetry of the Hamiltonian with respect to site permutations. For a given number of electrons and a given total spin the exchange term simply yields…
In present work the effective singlet-triplet model for CuO2-layer on the grounds of multiband p-d model of strongly correlated electrons is obtained. The resulting Hamiltonian has a form of generalized singlet-triplet t-t'-J model for…
From configuration interaction (CI) ab initio calculations, we derive an effective two-orbital extended Hubbard model based on the gerade (g) and ungerade (u) molecular orbitals (MOs) of the charge-transfer molecular conductor (TTM-TTP)I_3…
We present the detailed formalism of the extremely correlated Fermi liquid theory, developed for treating the physics of the t-J model. We start from the exact Schwinger equation of motion for the Greens function for projected electrons,…
The Emery model (aka the three-band Hubbard model) offers a simplified description of the copper-oxide planes that form the building blocks of high-temperature superconductors. By contrast with the even simpler one-band Hubbard model, it…
Mapping complex problems to simpler effective models is a key tool in theoretical physics. One important example in the realm of strongly correlated fermionic systems is the mapping of the Hubbard model to a t-J model which is appropriate…
We consider the behavior of Fermi atoms on optical superlattices with two-well structure of each node. Fermions on such lattices serve as an analog simulator of Fermi type Hamiltonian. We derive a mapping between fermion quantum ordering in…
We formulate the Hubbard model for the simple cubic lattice in the representation of interacting dimers applying the exact solution of the dimer problem. By eliminating from the considerations unoccupied dimer energy levels in the large U…
We present a theory for the lightly doped t-J model which is of possible relevance for the normal state of underdoped cuprates. Starting from an arbitrary dimer covering of the plane an exact representation of the t-J Hamiltonian in terms…
The effective low-energy models of the Hubbard model are usually derived from perturbation theory. Here we derive the effective model of the Hubbard model in spin space and t-J space using a unitary transformation from numerical…
Whereas the t-J model has gained wide popularity among physicists as a model for high-T_C superconductivity, its physical origin is not at all clear. In this communication we show that the Hubbard model with occupation-dependent hopping…
We investigate the Emery model on several ladder-like lattices including two legs of copper d-orbitals and various numbers of oxygen p-orbitals. Pair binding energy, pair spatial structure, density distribution, and pairing correlation…
An exact-diagonalization technique on small clusters is used to study the ground state of the dimerized t-J model at quarter filling. The equal-time charge and spin correlations, charge and spin gaps, and binding energy are calculated for…
We carry out a systematic study of collective spin- and charge excitations for the canonical single-band Hubbard, $t$-$J$-$U$, and $t$-$J$ models of high-temperature copper-oxide superconductors, both on electron- and hole-doped side of the…
We derive effective Hubbard-type Hamiltonians of $\kappa$-(ET)$_2X$, using an {\em ab initio} downfolding technique, for the first time for organic conductors. They contain dispersions of the highest occupied Wannier-type molecular orbitals…
Starting from the proper charge transfer model for Cu$_2$O$_5$ coupled ladders in Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$ we derive the low energy Hamiltonian for this system. It occurs that the widely used ladder t-J model is not sufficient and…
The direct exchange integral and the transfer integral are calculated for the anti-bonding wave-function of the HTSC cuprates. The direct exchange integral yields a value three times larger than the indirect exchange of the t-J Hamiltonian.…
We used quantum chemical ab initio methods to determine the effective parameters of Hubbard and $t-J$ models for the $\rm Na_{x}CoO_2$ compounds (x=0 and 0.5). As for the superconducting compound we found the $a_{1g}$ cobalt orbitals above…
It is demonstrated for the first time that the strong coupling between spin moments of copper ions and oxygen holes, which arises upon hybridazation mixing of two hole subsystems in the Emery model, not only affects the formation of spin…
An effective electronic Hamiltonian for transition metal oxide compounds is presented. For Mn-oxides, the Hamiltonian contains spin-2 ``spins'' and spin-3/2 ``holes'' as degrees of freedom. The model is constructed from the Kondo-lattice…