We derive an exact mapping from the action of nonequilibrium dynamical mean-field theory (DMFT) to a single-impurity Anderson model (SIAM) with time-dependent parameters, which can be solved numerically by exact diagonalization. The representability of the nonequilibrium DMFT action by a SIAM is established as a rather general property of nonequilibrium Green functions. We also obtain the noneq...

We investigate the doping of a geometrically frustrated spin ladder with static holes by a complementary approach using exact diagonalization and quantum dimers. Results for thermodynamic properties, the singlet density of states, the hole-binding energy and the spin correlations will be presented. For the undoped systems the ground state is non-degenerate, with translationally invariant neares...

We report exact diagonalization and diffusion quantum Monte Carlo calculations of quantum dots (QDs) in which energetics due to electron-electron interactions, magnetic field, and geometrical factors compete and induce interesting ground state configurations. The geometrical effects are generated by different confining potentials such as parabolic shaped, ring shaped, and disordered potentials....

Motivated by the recent experimental and theoretical progresses in exploration of effect disorder interacting system, we examine two types correlated disorder, quasi-periodic potential speckle potential, on one- two-particle problem with exact diagonalization (ED) method. We give phase diagram for single particle presence also analyse strong interaction ground state dimensions. For case, both c...

We study the low-lying spectrum of bilinear-biquadratic Heisenberg model in dimerized and Haldane phases using a tensor renormalization method. At critical point $\ensuremath{\theta}=\ensuremath{-}\ensuremath{\pi}/4$, finite-size predicted by Wess-Zumino-Witten (WZW) can only partly be confirmed. find singlet-singlet gap which does not fit into WZW systematics. The results obtained are compared...

We take the Bose–Hubbard model to illustrate exact diagonalization techniques in a pedagogical way. We follow the route of first generating all the basis vectors, then setting up the Hamiltonian matrix with respect to this basis and finally using the Lanczos algorithm to solve low lying eigenstates and eigenvalues. Emphasis is placed on how to enumerate all the basis vectors and how to use the ...

The one-dimensional (1D) t-J model is investigated by using a Gutzwiller-Jastrow-type variation method and the exact diagonalization of small systems. Variational expectation values are estimated by the variational Monte Carlo method with sufficient accuracy. First, we represent the diagonalization results. Physical quantities like momentum distribution and some correlation functions show some ...