Peng, Ding-Yu; Robinson, Donald B. A New Two-Constant Equation of State. Ind. Eng. Chem., Fundam. 1976, 15(1), 59-64.

Volume translation was first described in: Peneloux, A, and Rauzy, E. A consistent correction for Redlich-Kwong-Soave volumes. Fluid Phase Equilib. 1982, 8, 7-23. Translation is considered as a constant. (See, also: Pfohl, O. Evaluation of an improved volume translation for the prediction of hydrocarbon volumetric properties. Fluid Phase Equilib. 1999, 163, 157-159.) The purpose is to avoid crossing of isotherms at high densities, near critical conditions. If translation is set to zero, the original Peng-Robinson equation is recovered.

Parameters determined in TDE are:

critical temperature: T_c
critical pressure: p_c
acentric factor: w
volume translation term: v_t

Equation parameters are available in several formats from TDE: Equation Parameters in TDE