In exploiting tribological applications of diamondlike carbons (DLC, a-C:H), both elastic and plastic properties must be optimized. We use tight-binding molecular dynamics to generate realization of DLC, from which can be obtained properties and their dependence on the precursors used, and on the H/C ratio. Here we analyze the elastic properties and especially the rebonding events which occur under strain. Rebonding occurs only at rather large strains; in some cases, it is reversible. Hydrogen has a key role in determining the number of carbons with less than four carbon neighbors, since it is mainly these carbons which participate in the major plastic (rebonding) events. © 1998 American Institute of Physics.