UNIFAC model
The models/thermodynamics.a4l ASCEND code provides methods for calculating vapor-liquid equilibria (VLE).
Details on various group-contribution methods can be found here:
UNIQUAC: UNIQUAC model on Wikipedia
UNIFAC: UNIFAC model on Wikipedia
modified UNIFAC: A modified UNIFAC group-contribution model for prediction of phase equilibria and heats of mixing
The predictive Soave-Redlich-Kwong (PSRK) equation of state combines the Soave-Redlich-Kwong cubic equation of state with the Mathias-Copeman equation and the modified UNIFAC group-contribution method:
PSRK model on Wikipedia
See also predictive Soave-Redlich-Kwong (PSRK)
The UNIFAC consortium manages the parameter database for the original UNIFAC, modified UNIFAC and PSRK model: The UNIFAC Consortium
See also Thermodynamics with ASCEND.