Theoretical study of adsorption sites and thermodynamics of thionine in zeolite NaY

Abstract

The hybrid classical/quantum-mechanical dynamic annealing algorithm described recently (M. Müller, H.-J. Bär, S. M. Kast and J. Brickmann, Chem. Phys. Lett., 1999, 311, 485) was applied in a systematic study of the guest–host system thionine in zeolite NaY. Based on the statistical-mechanical analysis of all local minima of the PES the thermodynamics of the system is characterized within a discrete state approximation of the partition function. As a result, three dominant adsorption sites are identified. It is suggested that certain spectroscopic features of the system are readily explained by properties of the two lowest energetic minima.