Modelling Transition Metal Surfaces with Empirical Potentials
Julia Uppenbrink, Roy L. Johnston and John N. Murrell
School of Chemistry and Molecular Sciences, University of Sussex,
Falmer, Brighton BN1 9QJ, United Kingdom.
Article: Surface Science 1994, 304, 223-236.
Abstract
A study has been made of the surface energies and structures of Cu, Ag
and Au, using two empirical potentials, namely the two- plus three-body
potential of Murrell and Mottram (MM) and the many-body potential of
Sutton and Chen (SC). The MM potential reproduces bulk properties much
better than SC (particularly in respect of the phonon dispersion
curves), but for surface studies there are advantages and disadvantages
to both. The many-body potential underestimates the average surface
energies but gives the correct order of surface energies for different
surfaces. It correctly predicts a (1x2) reconstruction of the Au (110)
surface. The two- plus three-body potentialgives a much better match of
the average surface energies of different surfaces, and the correct
order of the unreconstructed surfaces. Two MM Au potentials have been
examined, one of which does not predict reconstruction of the (110)
surface, whereas the other favours (1x3) over (1x2) reconstruction. The
SC potential gives consistently greater relaxation of the surfaces than
the MM potential. Some of the atomic displacements in this
reconstruction are reproduced better with the MM potential than with the
SC potential.