  We apply the transfer matrix DMRG to frustrated quantum spin chains, going
down to T=0.025 while being in the thermodynamic limit. The incommensurability
problem of exact diagonalization and the negative sign problem of quantum Monte
Carlo vanish completely. To illustrate the method, we give results for chains
with next-nearest neighbor frustration and the delta chain, which has been a
testbed for many thermodynamic methods. By comparison, the DMRG proves to be an
extremely powerful method for the old problem of the thermodynamics of
frustrated systems.
