Ab initio localisation of adsorption sites in guest/host systems: application to the system thionine in zeolite NaY

An iterative optimization procedure for the localisation of adsorption sites of a guest molecule in a host system is proposed. The strategy uses quantum-mechanical and molecular-mechanical methods in a self-consistent manner. Important features are the ab initio quality of the geometry optimization, insight into the topography of the potential energy surface, and the `on the flyʹ refinement of force field parameters. Exemplary results are reported for the system thionine in zeolite NaY.