Critical behavior of the random Potts chain

We study the critical behavior of the random q-state Potts quantum chain by density-matrix renormalization techniques. Critical exponents are calculat ed by scaling analysis of finite lattice data of short chains (L less than or equal to 16) averaging over all possible realizations of disorder config urations chosen according to a binary distribution. Our numerical results s how that the critical properties of the model are independent of q in agree ment with a renormalization group analysis of Senthil and Majumdar [Phys. R ev. Lett. 76, 3001 (1996)]. We show how an accurate analysis of moments of the distribution of magnetizations allows a precise determination of critic al exponents, circumventing some problems related to binary disorder. Multi scaling properties of the model and dynamical correlation functions are als o investigated. [S0163-1829(99)13141-2].