W(001) (1 × 1) surface structure: pseudo-relativistic LEED calculations and R-factor analysis

Discrepancies in surface-to-bulk layer spacing contractions for W(001)(1 × 1) have been reported from previous LEED analyses, ranging between 4.5% and 11% (1.40 and 1.51 Å). In the present work LEED intensity spectra have been calculated using pseudo-relativistic phase shifts and a range of input parameters and compared with experimental results using an R-factor analysis. R-factors are also evaluated for non-relativistic spectra. Surprisingly, the pseudo-relativistic treatment does not lead to a significant improvement in the analysis. The analysis is improved, however, with an energy-dependent imaginary inner potential yielding from both the relativistic and non-relativistic spectra an inner potential of -11 to -12 eV and an interlayer spacing of 1.46 (+or-0.03) Å, corresponding to a contraction of 8(+or-1.5)%.