A renormalized excitonic method in terms of block excitations. Application to spin lattices

TL;DR

This paper introduces a renormalized excitonic method based on block excitations to analyze spin lattices, effectively locating phase transitions and understanding low-energy spectra in complex quantum systems.

Contribution

It presents a novel excitonic approach using block excitations to study spin lattice spectra and phase transitions, applicable to 1D and 2D frustrated systems.

Findings

Accurately locates phase transitions between gapped and non-gapped phases.

Successfully models low-energy spectra of complex spin lattices.

Demonstrates applicability to 1D and 2D frustrated systems.

Abstract

Dividing the lattice into blocks with singlet ground state and knowing the exact low energy spectrum of the blocks and of dimers (or trimers) of blocks, it is possible to approach the lowest part of the lattice spectrum through an excitonic type effective model. The potentialities of the method are illustrated on the 1-D frustrated chain and the 1/5-depleted square and the plaquette 2-D lattices. The method correctly locates the phase transitions between gapped and non-gapped phases.