LOG-PERIODIC CORRECTIONS TO SCALING - EXACT RESULTS FOR APERIODIC ISING QUANTUM CHAINS

Log-periodic amplitudes of the surface magnetization are calculated an alytically for two Ising quantum chains with aperiodic modulations of the couplings. The oscillating behaviour is linked to the discrete sca le invariance of the perturbations. For the Fredholm sequence, the ape riodic modulation is marginal and the amplitudes are obtained as funct ions of the deviation from the critical point. For the other sequence, the perturbation is relevant and the critical surface magnetization i s studied.