Fig. 1: Quasiperiodic Heisenberg chain.
From: Universality and quantum criticality in quasiperiodic spin chains

a Evolution of the couplings under renormalization for an Heisenberg chain with initial potential (3) with a = 1. The fluctuations decay with the number of RG steps and become completely negligible after a few Fibonacci steps. b The fluctuations about the sequence prediction (4) starting from a cosine potential decay exponentially with the number of Fibonacci RG steps m.