First-principles diffusion-barrier calculation for atomic oxygen on Pt(111)

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Abstract
An inconsistency is pointed out in adsorption energy values for O diffusion on Pt(111) in three recent studies: (A) the scanning tunneling microscope (STM)-deduced value of 0.43 eV for the diffusion barrier [J. Wintterlin, R. Schuster, and G. Ertl, Phys. Rev. Lett. 77, 123 (1996)]; (B) the calculated fcc-hcp adsorption-energy difference [P. J. Fiebelman, E. Stefanie, and M. Thomas, ibid.77, 2257 (1997)]; and (C) the STM-identified metastability of O in hcp sites [B. C. Stipe et al., ibid.78, 4410 (1997)]. Using accurate first-principles density-functional methods we obtain full agreement with (B) and (C) and a diffusion barrier of 0.58 eV, consistent with a reinterpretation of the raw data in (A). We further report on oxygen-induced surface buckling.