The spin-Peierls chain revisited

TL;DR

This paper revisits the phase diagram of a one-dimensional Heisenberg spin chain coupled to phonons, analyzing quantum phase transitions and validating analytical results with advanced DMRG calculations.

Contribution

It extends previous analytical studies by incorporating new DMRG methods and examining finite-size effects in different regimes.

Findings

Identification of a quantum phase transition from gapless to gapped phases

Different finite-size scaling behaviors in adiabatic and anti-adiabatic regimes

Validation of analytical results with DMRG calculations

Abstract

We extend previous analytical studies of the ground-state phase diagram of a one-dimensional Heisenberg spin chain coupled to optical phonons, which for increasing spin-lattice coupling undergoes a quantum phase transition from a gap-less to a gaped phase with finite lattice dimerisation. We check the analytical results against established four-block and new two-block density matrix renormalisation group (DMRG) calculations. Different finite-size scaling behaviour of the spin excitation gaps is found in the adiabatic and anti-adiabatic regimes.