Ground-state properties of the spin-1/2 antiferromagnetic Heisenberg model on the triangular lattice: A variational study based on entangled-plaquette states

TL;DR

This study employs entangled-plaquette variational states to accurately analyze the ground-state properties of the spin-1/2 antiferromagnetic Heisenberg model on a triangular lattice, achieving results comparable to the best existing methods.

Contribution

It introduces a variational approach based on entangled-plaquette states for this model, providing precise estimates of ground-state energy and order parameter.

Findings

Ground-state energy per site estimated at -0.5458(2)

Order parameter estimated at 0.3178(5)

Results agree with exact and advanced numerical methods

Abstract

We study, on the basis of the general entangled-plaquette variational ansatz, the ground-state properties of the spin-1/2 antiferromagnetic Heisenberg model on the triangular lattice. Our numerical estimates are in good agreement with available exact results and comparable, for large system sizes, to those computed via the best alternative numerical approaches, or by means of variational schemes based on specific (i.e., incorporating problem dependent terms) trial wave functions. The extrapolation to the thermodynamic limit of our results for lattices comprising up to N=324 spins yields an upper bound of the ground-state energy per site (in units of the exchange coupling) of $-0.5458(2)$ [$-0.4074(1)$ for the XX model], while the estimated infinite-lattice order parameter is $0.3178(5)$ (i.e., approximately 64% of the classical value).