FORCE FLUCTUATIONS AND LOCALIZED STATES AT POINT CONTACTS

The effect of atomic and electronic structure on mechanical properties of a piece of sodium nanowire is studied with a total-energy method b ased on the density functional theory. We find that adiabatic elongati on or compression of the wire results in discrete jumps in total energ y due to a correlated rearrangement of electron states and atomic stru cture. and the resulting force shows oscillations in the nanonewton ra nge. Furthermore, our results indicate that under certain conditions t he break contact could support well-localized electron states. We disc uss the results in connection with recent experiments and calculations on extended nanowires.