Theory of Surface Plasmons of the Alkali-Adatom-Chain Model on Si(100)2×1 Surfaces

With the use of the random-phase approximation, we obtained the dispersion relation of the inter- and intra-surface-band plasmon of the parallel-rod model, which simulates the alkali-metal adatom chains on Si(100)2×{}1 surfaces. There are two interband plasmon modes: One corresponds to the polarization vertical to the surface and the other to the polarization vertical to both the rod axis and the surface normal. The results explain fairly well the plasmon modes of the Si(100)(2×{}1) K surface observed recently.