Abstract: The 0°K relaxed structures of grain boundaries in Cu and its alloys (Cu-Ag, Cu-Bi) were simulated with molecular dynamics method by using a five-parameter potential and constant volume assumption.In these cases, the results showed that the atomic distribution was periodic in the two directions paralled to the grain boundary and it was mirror-symmetric in the direction perpendicular to the boundary. The difference between relaxed structures of Cu and its alloys was small, nevertheless, the host atoms were cl...