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Group contribution prediction of surface charge density profiles for COSMO-RS(Ol)



A new method for predicting the surface charge density distribution (σ profile) and cavity volume of molecules based on group contributions was developed. The original σ profiles used for the regression were obtained using Gaussian 03 B3LYP/6-311G(d,p). In total 1363 σ profiles were used for the regression of group parameters. Group definitions are identical to those used previously for boiling point estimation. Original and estimated σ profiles were used to predict activity coefficients at infinite dilution and VLE data of binary systems using the COSMO-RS(Ol) model. The results were compared with the experimental data stored in the Dortmund Data Bank. In many cases the results were of comparable accuracy. However, for a few compounds, poor results were obtained, in particular for conjugated components like nitrobenzenes. The method offers a fast and reliable generation of σ profiles to be used with COSMO-RS(Ol) within its range of applicability. © 2007 American Institute of Chemical Engineers AIChE J, 2007