Theory versus experiment in low-energy positron diffraction by Cu{111}

Four experimental spectra measured in a low-energy positron diffraction (LEPD) experiment on Cu{111} are satisfactorily matched by intensity calculations. The calculations were carried out with a computer program developed for LEED (low-energy electron diffraction) but using a potential consisting of negative Coulomb contribution, no exchange term and the correlation correction used normally for electrons. The present experimental data are not refined enough to show that positrons do not feel an exchange potential. © 1980.