  The magnetic deformation of the Ising Model, the thermal deformations of both
the Tricritical Ising Model and the Tricritical Potts Model are governed by an
algebraic structure based on the Dynkin diagram associated to the exceptional
algebras $E_n$ (respectively for $n=8,7,6$). We make use of these underlying
structures as well as of the discrete symmetries of the models to compute the
matrix elements of the stress--energy tensor and its two--point correlation
function by means of the spectral representation method.
