The structure and dynamics of the NaCl(100) single crystal surface were investigated at 25, 100, 160, and 230 K by means of low-energy electron diffraction (LEED). At each temperature, diffraction peak intensities of four inequivalent beam orders were recorded as a function of electron energy. The experimental I(V) data were analyzed using the tensor LEED approach. Compared to the unrelaxed bulk geometry, the Na+ ions in the topmost layer are displaced inwards by 0.09 +/- 0.03 A at all investigated temperatures. Moreover, the root-mean-square vibrational amplitudes of Na+ and Cl- ions in the topmost layer are enhanced significantly in the investigated temperature range. The amplitudes of the ions in the second layer are close to the bulk values. While the amplitudes of the cations in the second layer are larger than those of the anions, Na+ and Cl- in the topmost layer have nearly equal vibrational amplitudes at temperatures above 100 K. In this temperature range, the mean-square amplitudes of vibrations of ions at the surface and in the bulk are in good agreement with previously reported lattice dynamics studies.
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