ON THE CRITICAL-BEHAVIOR OF THE ANISOTROPIC BIQUADRATIC SPIN-1 CHAIN

A study is made in the anisotropic biquadratic spin-1 Hamiltonian introduced by Batchelor et al. This model can be represented as a sum of operators satisfying a Temperley-Lieb algebra. Its critical behaviour is explored by using the relations between mass-gap amplitudes and critical exponents predicted by conformal invariance. The model, like in the XXZ chain, is found to exhibit a line of continuously varying exponents. By comparing its eigenspectrum with that of the XXZ Hamiltonian, several exact values are predicted.