Both the formation energies and the diffusive activation energy of a single vacancy migrating intra- and inter-layer in the first four atomic planes near Cu Sigma = 5[ 0 0 1] twist GB have been investigated by means of MD in conjunction with MAEAM. The effects of the GB on the vacancy formation and migration are only to the third layer. The vacancy is favorable to be formed on the un-coincident site in the first, second and third layers near the GB plane and this case is enhanced successively following the third, second and first layers. A single vacancy either on un-coincident site or on coincident site in the forth, third and second layers is favorable to migrate to un-coincident site ( its first-nearest-neighbor) in its adjacent layer near the GB. But for the first layer, the favorable migration path of the vacancy on the un-coincident site is between un-coincident sites of the first layer or to its nearest-neighbor of the first layer in the rotating grain, which is not the case for the vacancy on the coincident site '1' that is migrated difficultly. So, there are collective tendency of the vacancy in the GB. (c) 2009 Elsevier B.V. All rights reserved.