Predict thermodynamic properties of solutions
from DFT data. Quick estimates from SMILES.
Screen solvents for desired logP, VLE, LLE.


Fluid thermodynamics from quantum mechanics

The COnductor-like Screening MOdel for Realistic Solvents calculates thermodynamic properties of fluids and solutions based on quantum mechanical data. Properties from COSMO-RS have predictive power outside the parametrization set, as opposed to empirical models (e.g. UNIFAC).

COSMO-RS properties

  • solubilities, partition coefficients (log P, log kOW)
  • pKa values
  • activity coefficients, solvation free energies, Henry’s law constants
  • vapor pressures, boiling points, vapor-liquid diagrams binary and ternary mixtures (VLE/LLE)
  • excess energies, azeotropes, miscibility gaps
  • composition lines, flash points

A database of 1892 compounds (solvents, small molecules) facilitates instantaneous predictions of log P, solubilities, and other properties. It is easy to add other molecules to the database with a prescribed ADF calculation. Tutorials show step-by-step how to set up COSMO-RS property calculations with the GUI. Scripting tools enable rapid solvent screening, e.g. to find the solvent combination which best partitions a drug and its main contaminant, or to determine the best excipients.

vapor pressure with COSMO-SAC in COSMO-RS


We also offer the COSMO-SAC (segmented activity coefficients) model. The recent reparametrization of COSMO-SAC by Stan Sandler’s group improves partition coefficients (logP) for a set of solvent combinations. Furthermore, vapor-liquid equilibrium predictions are improved yielding a better agreement between calculated and experimental vapor pressures of mixtures. Even higher accuracy may be achieved by including 3D contact information (COSMO-SAC-3D) as well as including pure solvent data (e.g. DIPPR).

Solvent screening with COSMO-RS

The included scripting tools enable easy screening of solvents and solvent combinations for particular properties. Chemical engineers can thus optimize distillation processes by tweaking vapor pressures, while medicinal chemists can maximize solvent extraction efficiency by fine-tuning partition coefficients for a set of solvent and solute combinations.

Other applications for scripting with COSMO-RS include optimizing catalysts, solubility parameters, pKa values and sorption in ionic liquids.

Very quick COSMO-RS predictions

In the 2017 development version, very quick estimators have been implemented. Sigma profiles can be instantaneously predicted from SMILES strings or an xyz file, based on group-contribution methods. The group-contribution based UNIFAC has also been implemented with very fast and accurate -within its parameterization scope- predictions for many thermodynamics properties.

News item: quick COSMO-RS