arXiv subjects

Eric Jeckelmann

Publications and source records attributed to Eric Jeckelmann.

40 records · Page 3Linked to original sources

arXiv1997

Stripes in a three-chain Hubbard ladder: a comparison of density-matrix renormalization group and constrained-path Monte Carlo results

Using both the density-matrix renormalization group method and the constrained-path quantum Monte Carlo method, we have studied the ground-state energies and the spin and hole densities of a $12 \times 3$ Hubbard model with open boundary conditions and 6 holes doped away from half-filling. Results obtained with these two methods agree well in the small and intermediate $U$ regimes. For $U/t \geq 6$ we find a ground-state with stripes.

cond-mat.str-el↗

arXiv1997

Mott-Peierls Transition in the extended Peierls-Hubbard model

The one-dimensional extended Peierls-Hubbard model is studied at several band fillings using the density matrix renormalization group method. Results show that the ground state evolves from a Mott-Peierls insulator with a correlation gap at half-filling to a soliton lattice with a small band gap away from half-filling. It is also confirmed that the ground state of the Peierls-Hubbard model undergoes a transition to a metallic state at finite doping. These results show that electronic correlations effects should be taken into account in theoretical studies of doped polyacetylene. They also show that a Mott-Peierls theory could explain the insulator-metal transition observed in this material.

cond-mat.str-el↗

arXiv1997

Density matrix renormalization group study of the polaron problem in the Holstein model

We propose a new density matrix renormalization group (DMRG) approach to study lattices including bosons. The key to the new approach is an exact mapping of a boson site containing 2^N states to N pseudo-sites, each with 2 states. The pseudo-sites can be viewed as the binary digits of a boson level. We apply the pseudo-site DMRG method to the polaron problem in the one- and two-dimensional Holstein models. Ground state results are presented for a wide range of electron-phonon coupling strengths and phonon frequencies on lattices large enough (up to 80 sites in one dimension and up to 20x20 sites in two dimensions) to eliminate finite size effects, with up to 128 phonon states per phonon mode. We find a smooth but quite abrupt crossover from a quasi-free electron ground state with a slightly renormalized mass at weak electron-phonon coupling to a polaronic ground state with a large effective mass at strong coupling, in agreement with previous studies.

cond-mat↗

arXiv1997

Density Matrix Approach to Local Hilbert Space Reduction

We present a density matrix approach for treating systems with a large or infinite number of degrees of freedom per site with exact diagonalization or the density matrix renormalization group. The method is demonstrated on the 1D Holstein model of electrons coupled to Einstein phonons. In this system, two or three optimized phonon modes per site give results as accurate as with 10-100 bare phonon levels per site.

cond-mat.supr-con↗