The 5×20 surface structure of gold

Abstract
A precision RHEED investigation of the so‐called Au (100) (5×20) surface structure has shown that its basic unit is in reality a primitive hexagonal cell, or a similar cell rotated 90° with respect to the first. The cell is repeated by translation in two dimensions, and coincidence occurs in one basic. Au repeat direction only. The designation 5×20, which implies coincidence in two directions, is therefore inappropriate and misleading.