Pyridine adsorbed on H-Faujasite zeolite: Electrostatic effect of the infinite crystal lattice calculated from a point charge representation

Calculations on duster models of infinite systems require less computational effort and are technically simpler than periodic calculations, but they neglect, among other contributions, the effect of long-range electrostatic interaction from the infinite crystal lattice. In the case of zeolites, such contributions can be important for adsorption processes and surface reactions. We test a simple method for including this effect into the calculation by generating a finite number of point charges placed on the lattice sites. These point charges reproduce the infinite electrostatic potential at the chemically important region of the zeohte. We apply this method to the adsorption of pyridine on H-Faujasite zeohte. The embedding method gives an adsorption energy of -42.8 kcal/mol, which agrees well with the experimental value of -43.1 +/- 1 kcal/mol. Without the electrostatic effect of the crystal field, the value is similar to 9 kcal/mol higher. (c) 2005 Wiley Periodicals, Inc.