(620c) Reconsideration of the Hydrogen Bong Interaction Energy Expression in the COSMO-RS Model

The Conductorlike Screening Model for Real Solvents (COSMO-RS) meanwhile has become one of the standard approaches for predictive simulation of fluid phase thermodyanamic properties. COSMO-RS covers electrostatic interactions and hydrogen bond interactions by interaction energy expressions based on ths conductor-polarization charge densities sigma and sigma' of molecular surfaces, as calculated from quantum chemical COSMO calculations. While the expression for the electrostatic energy has a rather physical justification, the hydrogen bond term was derived from plausibility arguments. Nevertheless, it appeared to work reasonably predictive.

In a major project we have reconsidered the hydrogen bond interaction term of COSMO-RS. By quantum chemical calculation of thousands of hydrogen bonded dimmers, we were able to confirm the bilinear dependence of the hydrogen bond interaction actions with respect to sigma and sigma'. Beyond that, this theorectial reference da set led us to new, interesting insights with respect to lone-pair constraints and steic hindrance, which have not been taken into account previously.

The new concepts will be presented together with results of a new HB2010-COSMO-RS parameterization.