Using stationary points on potential energy surfaces to model intermolecular interactions and retention in gas chromatography

The utility of electronic structure methods for studying and predicting interactions in gas chromatography is explored using a simplified model of polyethylene glycol with a homologous series of normal alcohols. Relative interaction energies were determined using stabilization energies taken at stationary points on the analyte/stationary phase potential energy surfaces using semi-empirical, ob initio, and density functional theory. Second order Moller-Plesset electronic structure method produced good qualitative agreement with experiment, clearly indicating the need for a model that includes weak dispersion forces.