Structure determination of Ag(111) by low-energy electron diffraction

A quantitative structure determination of the Ag(111) clean surface has bee n performed using low-energy electron diffraction. Optimisation of the oute rmost layer spacings and vibrational amplitudes was achieved using two diff erent dynamical scattering computational methods, one using the LEEDFIT cod e and the second exploiting a Simulated Annealing algorithm implemented on the conventional Van Hove/Tong code. The results obtained show that a bulk- terminated structural model describes the data best (Delta d(12)=0.00 +/- 0 .02 Angstrom and Delta d(23) = 0.00 +/- 0.03 Angstrom), and in particular, the analysis excludes a 2.5% contraction of the outermost layer spacing, wh ich was recently reported on the basis of ion-scattering measurements. The LEED result of no contraction is consistent with prior results for the (111 ) face of several other fee metals. (C) 1999 Elsevier Science B.V. All righ ts reserved.