Thermodynamics of the random antiferromagnetic spin-1 chain

The random exchange antiferromagnetic Heisenberg spin-1 chain at finite tem perature is studied using a renormalization-group method. We follow the evo lution of the bond probability distribution and calculate the free energy o f the system. The spurious results found for the free energy shows that the standard renormalization group approach used for spin-1/2 chains does not guarantee the existence of the random singlet phase in the random spin-1 ch ain even in the presence of strong disorder. (C) 2001 Elsevier Science B.V. All rights reserved.