COMPARISON OF CLUSTER AND INFINITE CRYSTAL CALCULATIONS ON ZEOLITES WITH THE ELECTRONEGATIVITY EQUALIZATION METHOD (EEM)

In the present work the validity of the finite cluster approximation i s investigated for two zeolite types, faujasite (FAU) and zeolite A (L TA), by comparison of crystal calculations, with cluster calculations, both performed at the same level of accuracy within the EEM frame. Th e quantities under consideration are the electronegativity, the chemic al hardness, the electrostatic potential, and the electrostatic field. A criterion for the determination of the valid region of a cluster is proposed. Also, a method is offered to approximate the structure spec ific, long-range Madelung potential used for embedding of clusters.