[111] Intrinsic Gap Mode Eigenvector in FCC Structure
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The intrinsic localized gap mode vibrating in the [111] direction is shown for fcc lattice of NaI crystal. The amplitude of the central Na-ion is 24% of the nearest-neighbor distance (a/d=0.244). The frequency of the shown intrinsic gap mode lies 5% down in the gap between optic and acoustic phonon bands (W/W+=0.95). The magnitude of the axial elastic distortion is enhanced by 5 times for clearity. Small circles, Na+ ions; large circles, I- ions.
Last modified: April 3, 1997