On c = 1 critical phases in anisotropic spin-1 chains
INFM Research Unit of Bologna, 6/2 v.le B. Pichat, 40127 Bologna Italy
2 Physics Department, University of Bologna, and INFN, 6/2 v.le B. Pichat, 40127 Bologna, Italy
Corresponding author: a email@example.com
Published online: 24 October 2003
Quantum spin-1 chains may develop massless phases in presence of Ising-like and single-ion anisotropies. We have studied c=1 critical phases by means of both analytical techniques, including a mapping of the lattice Hamiltonian onto an O(2) NLσM, and a multi-target DMRG algorithm which allows for accurate calculation of excited states. We find excellent quantitative agreement with the theoretical predictions and conclude that a pure Gaussian model, without any orbifold construction, describes correctly the low-energy physics of these critical phases. This combined analysis indicates that the multicritical point at large single-ion anisotropy does not belong to the same universality class as the Takhtajan-Babujian Hamiltonian as claimed in the past. A link between string-order correlation functions and twisting vertex operators, along the c=1 line that ends at this point, is also suggested.
PACS: 75.40.-s – Critical-point effects, specific heats, short-range order / 75.10.Jm – Quantized spin models / 02.70.-c – Computational techniques
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003