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I've been reading about surface reconstruction in condensed matter physics, and it got me wondering. Is there any way to assign a time scale to this phenomenon?

For example, suppose we were to take a slab of pure silicon and cleave it, as described in the Wikipedia article, along the (100) surface. The atoms on the new surface are going to relax to a new optimal configuration and form dimers. Is there a way to estimate how long it's going to take them to relax? Since the difference in energy between the two structures is large, does it happen basically as we're cleaving them, as the edge of the cutting surface is moving along them?

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  • $\begingroup$ This happens instantaneous. The system becomes unstable so it immediately adopts a new crystal structure at the surface by surface relaxation or reconstruction. $\endgroup$ – Simon Nov 22 '19 at 20:43
  • $\begingroup$ @Simon but that's a bit of a paradox, isn't it? All relaxation processes I know about have some e^(-Lamba t) like time dependence and don't happen instantaneously, barring, maybe, the diffusion equation with a Dirac Delta initial condition (which jumps from a discontinuous state to a continuous one, but that's more like a result of the delta initial condition being an approximation anyway). $\endgroup$ – Perfi Nov 23 '19 at 8:06

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