The observation of metallic ground states in a variety of two-dimensional electronic systems
poses a fundamental challenge for the theory of electron fluids. Here evidence is analyzed …

The density matrix renormalization group (DMRG) is one of the most powerful numerical
methods for studying two-dimensional quantum lattice systems, despite a perception that it is …

Motivated by experimental studies that have found signatures of a quantum spin liquid
phase in organic crystals whose structure is well described by the two-dimensional …

The antiferromagnetic spin-1/2 Heisenberg model on a kagome lattice is one of the most
paradigmatic models in the context of spin liquids, yet the precise nature of its ground state …

These lecture notes introduce quantum spin systems and several computational methods for
studying their ground‐state and finite‐temperature properties. Symmetry‐breaking and …

States of matter with a sharp Fermi surface but no well-defined Landau quasiparticles arise
in a number of physical systems. Examples include (i) quantum critical points associated …

The nature of quantum spin liquids, a novel state of matter where strong quantum
fluctuations destroy the long-range magnetic order even at zero temperature, is a long …

We review ground states and excitations of a quantum antiferromagnet on triangular and
other frustrated lattices. We pay special attention to the combined effects of magnetic field h …

We review the interplay of frustration and strong electronic correlations in quasi-two-
dimensional organic charge transfer salts, such as (BEDT-TTF) 2 X and Et n Me 4− n Pn [Pd …

We study the spin-1 2 Heisenberg model on the triangular lattice with antiferromagnetic first-
(J 1) and second-(J 2) nearest-neighbor interactions using density matrix renormalization …