Critical behaviour of spin-s Heisenberg antiferromagnetic chains: analytic and numerical results

A general phase diagram for isotropic antiferromagnetic chains has been proposed recently, using conformal field theory. This is developed further to predict the spectrum of finite chains, including logarithmic corrections. These predictions are tested against Bethe ansatz and exact diagonalisation results for various Hamiltonians with s=1/2, 1 and 3/2. Logarithmic corrections to correlation functions and the scaling of gaps for infinite systems are also given.