3 research outputs found
Competition between Hund's coupling and Kondo effect in a one-dimensional extended periodic Anderson model
We study the ground-state properties of an extended periodic Anderson model
to understand the role of Hund's coupling between localized and itinerant
electrons using the density-matrix renormalization group algorithm. By
calculating the von Neumann entropies we show that two phase transitions occur
and two new phases appear as the hybridization is increased in the symmetric
half-filled case due to the competition between Kondo-effect and Hund's
coupling. In the intermediate phase, which is bounded by two critical points,
we found a dimerized ground state, while in the other spatially homogeneous
phases the ground state is Haldane-like and Kondo-singlet-like, respectively.
We also determine the entanglement spectrum and the entanglement diagram of the
system by calculating the mutual information thereby clarifying the structure
of each phase.Comment: 9 pages, 9 figures, revised version, accepted for publication in PR
The Density Matrix Renormalization Group for finite Fermi systems
The Density Matrix Renormalization Group (DMRG) was introduced by Steven
White in 1992 as a method for accurately describing the properties of
one-dimensional quantum lattices. The method, as originally introduced, was
based on the iterative inclusion of sites on a real-space lattice. Based on its
enormous success in that domain, it was subsequently proposed that the DMRG
could be modified for use on finite Fermi systems, through the replacement of
real-space lattice sites by an appropriately ordered set of single-particle
levels. Since then, there has been an enormous amount of work on the subject,
ranging from efforts to clarify the optimal means of implementing the algorithm
to extensive applications in a variety of fields. In this article, we review
these recent developments. Following a description of the real-space DMRG
method, we discuss the key steps that were undertaken to modify it for use on
finite Fermi systems and then describe its applications to Quantum Chemistry,
ultrasmall superconducting grains, finite nuclei and two-dimensional electron
systems. We also describe a recent development which permits symmetries to be
taken into account consistently throughout the DMRG algorithm. We close with an
outlook for future applications of the method.Comment: 48 pages, 17 figures Corrections made to equation 19 and table