Quantumchemical (COSMO-RS-Type) Models

After the great success of COSMO-RS (A. Klamt, COSMOLogic), similar models were developed by various research groups. 

DDBSP contains implementations of COSMO-RS(Ol) and COSMO-SAC that can be used for the estimation of different types of phase equilibria and excess properties.

COSMO-RS and similar models derive the residual contribution to the activity coefficient from shielding charge density missfit interactions between contacting surface segments of the molecules. The different shielding charge densities are depicted by different colors for cyclohexane and nitromethane in the picture on the right. Instead of bringing the 3-dimensional representations of the molecules into contact, COSMO-RS models assume that the probability of contact of two surface segments is only governed by the size of energy missfit. This greatly simplifies the calculation as only the shielding charge density distribution (s-profile) has to be considered.

The required s-profiles were derived using the program package Gaussian  using the B3LYP DFT functional and the 6-311G(d,p) basis set and are delivered as a separate databank (s-Profile Data Bank).

Quantumchemical calculations are especially tedious in case of large molecules. To provide a reliable alternative, the program package DDBSP-ARTIST allows to estimate the required s-profiles via group contribution.

 

 

Scientific Papers

2009    Group Contribution Prediction of Surface Charge Density Distribution of Molecules for COSMO-SAC    Mu T., Rarey J., Gmehling J.    Journal    AIChE J., 55, 12, 3298 3300 (2009)
2009    Application of COSMO-RS Type Models to the Prediction of Excess Enthalpies    Constantinescu D., Rarey J., Gmehling J.    Journal    Ind.Eng.Chem.Res., 277, 1,8710-8725 (2009)
2008    Reply to: Comments on Performance of COSMO-RS with Sigma Profiles from Different Model Chemistries    Mu T., Rarey J., Gmehling    Journal    Ind.Eng.Chem.Res., 47, 3, 989 989 (2008)
2008    Conductor-Like Screening Model for Real Solvents ( COSMO-RS)    Mu T., Gmehling J.    Journal    Huaxue-jinzhan, 20, 10, 1487 1494 (2008)
2007    Performance of COSMO-RS with Sigma Profiles from Different Model Chemistries    Mu T., Rarey J., Gmehling J.    Journal    Ind.Eng.Chem.Res., 46, 20, 6612 6629 (2007)
2007    Group Contribution Prediction of Surface Charge Density Profiles for COSMO-RS(Ol)    Mu T., Rarey J., Gmehling J.    Journal    AIChE J., 53, 12, 3231 3240 (2007)
2005    Weiterentwicklung thermodynamischer Vorhersagemodelle durch Einsatz von quantenchemischen Methoden    Grensemann H.    PhD thesis    Thesis, Carl-von-Ossietzky-Universität Oldenburg, 1-235, 2005
2005    Rebuttal to the Comments of Andreas Klamt on "Performance of a COSMO-RS Model in Comparison to Classical Group Contribution Methods"    Grensemann H., Gmehling J.    Journal    Ind.Eng.Chem.Res., 44, 17, 7043 7044 (2005)
2005    Systems with Ionic Liquids: Measurement of VLE and gamma-infinite Data and Prediction of their Thermodynamic Behavior using Original UNIFAC, mod. UNIFAC(Do) and COSMO-RS(Ol)    Kato R., Gmehling J.    Journal    J.Chem.Thermodyn., 37, 6, 603 619 (2005)
2005    Performance of a Conductor-Like Screening Model for Real Solvents Model in Comparison to Classical Group Contribution Methods    Grensemann H., Gmehling J.    Journal    Ind.Eng.Chem.Res., 44, 5, 1610 1624 (2005)

 

Sigma-Profiles for COSMO-RS Type Models

For the use with COSMO-RS type models like e.g. COSMO-RS, COSMO-SAC and COSMO-RS(Ol), a large data bank with the required sigma profiles has been prepared. As the quantumchemical calculations become very demanding for large molecules, group contribution methods have been developed to predict sigma profiles. These complimentary methods are delivered with DDBSP-Artist and lead to reliable results for not too complex or multifunctional structures.

Sigma profiles from DDB-Sigma can be used within the DDBSP software (DDBSP Mixture Predict Add-On) and in most third party software (in COSMOTherm® a specially optimized parametrization for these profiles is available).