"Modeling Substituent and Macromolecular Effects on the Molecular Electronic Structure"
Abstract: Molecular electronic structures can be perturbed by chemical substitutions and solvent/macromolecular environments. In this seminar, we will discuss how common electron-donating and withdrawing groups affect the HOMO/LUMO orbital energies of simple fluorophores and thus their absorption/emission wavelengths. Different patterns for the interactions between substituent and fluorophore orbitals will be shown. We will also discuss ways to speed up the modeling of ab initio QM/MM free energy profiles of enzymatic reactions. A dual-Hamiltonian approach, where a semi-empirical QM/MM simulation is combined with an ab initio QM/MM thermodynamical perturbation, will be shown to produce ai-QM/MM-quality results for several reactions.