The paper shows how the characteristic time exponent z in slowing down
, and the fractal dimension of the order parameter field, are uniquely
determined by distinct forms of special thermodynamic functions that
describe the interacting systems with some terms of phi(n). It is also
shown that for the purpose of obtaining critical exponents, the renor
malization group transformation is needed just to perform to the power
s of the order parameter and not to their coefficients in thermodynami
c functions. This advantage leads to results which are analytically ex
act.