Monatomic metal nanowires: Rupture kinetics and mean lifetime

• Spontaneous rupture of monatomic metal nanowire on (111) crystal face occurs in three steps.
• Steps 1 is formation of active atoms, step 2 is appearance of atomic vacancies, step 3 is birth of hole.
• The first few vacancies and holes in the nanowire appear randomly according to a Poisson process.

We present a model for the kinetics of spontaneous (unforced) rupture of monatomically thick metal nanowire on atomically smooth crystal face. The nanowire breaks down spontaneously solely because of the thermal motion of the atoms in it and the underlying crystal. Our model describes the nanowire rupture as a three-step process involving (i) appearance of atoms active in vacating their positions, (ii) generation of atomic vacancies, and (iii) formation of holes (vacancy dimers) in the nanowire. The model is based on Monte Carlo simulation results for the temporal evolution of initially straight monatomic chain of Cu atoms on Cu(111) crystal face. The simulation provides data for the time dependence of the number Nv of vacancies and the number Nh of holes in the nanowire, as well as for the probabilities Pv and Ph to form, respectively, at least one vacancy and at least one hole until time t. We describe the nanowire rupture kinetics by using rate equations and obtain expressions for the nanowire mean lifetime and the Nv(t), Nh(t), Pv(t), and Ph(t) dependences. These expressions are found to conform well to the simulation data, which implies a Poissonian random appearance of the first few vacancies and holes in the nanowire.

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