Predict thermodynamic properties of solutions.
Quick physical property estimates.
Screen solvents for solubility, logP, VLE, LLE.

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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).

Instantaneous thermodynamic property prediction

  • solubilities, partition coefficients (log P, log kOW)
  • pKa values (empirical fit improves predictions: tutorial)
  • 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 over 2500 compounds containing solvents & small molecules (list) and ionic liquids (list, tutorial ionic liquids) 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 and quick estimation from SMILES strings. 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.

Try for yourself!
Overview: our developer Nick Austin talks you through some key features in COSMO-RS:

  • quick sigma profiles for COSMO-RS & COSMO-SAC
  • UNIFAC & QSPR prediction of many properties
  • optimizing solvent mixtures for solubility or extraction

Thermodynamic Properties for Polymer solutions
Nick Austin demonstrates new features in COSMO-RS(-SAC) for dealing with polymers.

Solvent screening with COSMO-RS

Chemical engineers may want to optimize distillation processes by tweaking vapor pressures and boiling points, while medicinal chemists perhaps want maximize solvent extraction efficiency to separate the active pharmaceutical ingredient from its main contaminant, or maximize solubility with excipients.

Our solvent system optimization tool is perfectly placed to help reduce the experimental search space by optimizing solvent mixtures for solubility or liquid-liquid extraction across a set of selected solvents.

This tool will be expanded to other solvent optimization problems. In the meantime the included scripting tools enable easy screening of solvents and solvent combinations for particular properties.

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

The SCM team is eager to hear about how our software can be used to tackle your solvent optimization challenge – discuss your research! Do let us know if you have any requests for new solvent optimization templates!

Conformers, aggregates, protonation states

In AMS2020, you can deal with more complex solution behavior where compounds may behave differently in various solvents or under different conditions. These include case where the solute dissociates, aggregates, or has multiple conformers (see tutorial).

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. There are also other COSMO-SAC parametrizations available from the groups of Lin and Lei.  Even higher accuracy may be achieved by including pure solvent data (e.g. DIPPR).

COSMO-RS fast calculations

Very quick COSMO-based and QSPR predictions

Very quick estimators are available in our 2018 release. Sigma profiles, volumes, and areas are instantaneously predicted from SMILES strings or an xyz file, which can then be used in COSMO-RS or COSMO-SAC thermodynamic property predictions.

The group-contribution based UNIFAC activity coefficient method has also been added, which offers very fast and accurate predictions for many thermodynamic properties within its parametrization scope.

In 2018, we have also implemented instantaneous QSPR predictors for a range of different physical properties such as heat of melting, boiling point, flash point, critical temperature, etc.

COSMO-RS 2019 also features a new vapor pressure predictor in our quick pure compound property prediction module.

News item: quick COSMO-RS
COSMO-RS sigma profile for monomer in polymer


COSMO-RS and COSMO-SAC also predict thermodynamic properties and descriptors for polymers such as activity coefficients, vapor pressures, partition coefficients, solubilities, and Flory-Huggins Chi. In combination with the new polymer builder of the graphical user interface, these new features significantly extend the polymer tools in AMS2019.

Tutorial: polymer properties with COSMO-RS