Journal of Statistical Physics, Vol. 71, Nos. 5/6, 1993. p. 903-921.
We demonstrate the relation of the infrared momentum restrictions of conformal field theory with entropy considerations of finite-temperature thermodynamics for the 3-state Ports chain. We compute the free energy and obtain the low-temperature specific heat for both the ferromagnetic and antiferromagnetic spin chains, and find the central charges for both.