On a large class of lattices (such as the sawtooth chain, the kagome and the pyrochlore
lattices), the quantum Heisenberg and the repulsive Hubbard models may host a completely …

In recent times, ab initio density functional theory has emerged as a powerful tool for making
the connection between models and materials. Insulating transition metal oxides with a …

We use a combination of numerical density matrix renormalization group calculations and
several analytical approaches to comprehensively study a simplified model for a spatially …

Abstract The spin-1/2 frustrated Heisenberg model (HM) is investigated using a block-spin
perturbation approach on kagome $ aai—and triangular lattices. In both cases, after coarse …

Motivated by the intriguing properties of the vanadium spin tube Na 2 V 3 O 7, we show that
an effective spin-chirality model similar to that of standard Heisenberg odd-legged S= 1 2 …

Following the recent discussion on the puzzling nature of the interactions in the nanotubular
system Na 2 V 3 O 7, we present a detailed ab initio microscopic analysis of its electronic …

We consider the antiferromagnetic Heisenberg and the repulsive Hubbard model on two N-
site one-dimensional lattices, which support dispersionless one-particle states …

We present a microscopic theory of a lateral quantum dot molecule in a radial magnetic field
with a Greenberger-Horne-Zeilinger (GHZ) maximally entangled three particle ground state …

A one-dimensional model of coupled spin-1/2 spins and pseudospin-1/2 orbitals with
nearest-neighbor interaction is rigorously shown to exhibit spin-orbital separation by means …

A 2× L system of coupled spin-1 2 Heisenberg chains is studied in the framework of
variational approach. An effective Hamiltonian is derived explicitly in terms of two spin-1 …