A density functional theory study of adsorbate-induced work function change and binding energy: Olefins on Ag(111)

Abstract

The change of work function of the Ag (111) surface induced by the physisorption of ethylene and its derivatives, vinyl chloride and butadiene, is examined with density functional theory (DFT) calculations employing a generalized gradient approximation for the exchange correlation functional. It is found that the calculations can generate optimized adsorption structures in agreement with experiment, although as expected the calculation does not compute the small binding energies accurately. This DFT approach, however, predicts the work function change induced by adsorption reasonably well. Since there appears an empirical correlation between the measured adsorption energy and the calculated work function change for the studied olefins that can be justified by molecular orbital interactions, the work function changes computed within DFT may be used as a relative calibration for binding energies in physisorbed systems.

Acknowledgement

The authors thank Dr Yashar Yourdshahyan for advice relating to surface energy calculations, and Drs J. S. Filhol and D. Pursell for stimulating discussions. This work is supported in part by the NSF MRSEC programme under grant DMR00-79909. AMR and HLD acknowledge support from the Air Force Office of Scientific Research, Air Force Materiel Command, USAF, under grant numbers FA9550-04-1-0077 and F49620-01-1-0517, respectively.