Equilibrium dynamics of the sub-Ohmic spin-boson model under bias
Zheng Da-Chuan, Tong Ning-Hua
       

(color online) (a)–(c) The flow diagrams for three different α values. For each α, from right to left ε = 0, 10−7, 10−6, 10−5, 10−4, and 10−3. The empty squares make out the crossover for the case . The solid circle marks out the crossover scale in the unbiased case . In panel (c), . NRG parameters are , , and .