Determination of the lateral energy variation for the uniaxial incommensurate phase of potassium on Ni(100)

Structure-factor calculations for the uniaxial incommensurate phase of potassium on Ni(100) show that slight modulations in the overlayer structure have a significant impact on the relative magnitudes of the diffraction peaks. Comparison of the relative intensities observed in low-energy electron diffraction results from K/Ni(100) show that the density modulation is weak. A simple model in which the adsorbate-adsorbate interaction is approximated by a dipole-dipole repulsion is used to find that the substrate lateral energy variation is 0.10 eV at a coverage of 0.27.