Buckled reconstruction of the alkali-metal (Na, K)-adsorbed Si(111)-(3×1) surfaces

The atomic and electronic structures of the alkali-metal (Na, K)-adsorbed Si(111)-(3×{}1) surface are studied by the pseudopotential density-functional total-energy scheme for the structural models proposed to date: the missing-top-layer (MTL), {π}-bonded chain, and overlayer models including their variations. From the extensive investigation of them, we propose the MTL model as the ground-state structure of this system based both on the energetics and on the comparison of the calculated electronic structures with recent angle-resolved ultraviolet photoemission data. {} 1996 The American Physical Society.