Yes, Both Au (111) and Si (111) are face centered cubic.. which means 8 corners (8 atoms) and 6 faces (6 atoms).. totally 14 atoms... but these 8 corners are shared with other cubes and the same for faces (6 faces shared with other cubes).. Now, my doubt is Is all fcc single crystals have 14 atoms? Please comment about this I may not be correct...