Molecular-dynamics study of craters formed by energetic Cu cluster impact on Cu

We study crater formation induced by energetic Cu-n (n = 13, 43) cluster im pact with energies between 5 and 20 keV on a Cu (1 0 0) surface. Due to the melt film covering the crater walls and to the high atomic mobility in the crater rims, the stabilisation of the final crater shape and volume lasts up to 20 ps. Craters are formed above a threshold bombarding energy of arou nd 5 keV; then the crater volume increases linearly with bombarding energy. The crater shape is roughly hemispherical; towards the threshold, craters become shallow. By modifying the interatomic many-body potential, we study the influence of the target cohesive energy on the crater size, and find an inverse-square dependence. Comparison with observations of cratering induc ed by macroscopic impact (such as meteorites) is discussed. (C) 2000 Elsevi er Science B.V. All rights reserved.