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Toward mechanosynthesis of diamondoid structures: II. Quantum-chemical molecular dynamics simulations of mechanosynthesis on an hydrogenated Si(111) surface with STM

The controlled manipulation of silicon atoms and silylene molecules at the subnanometre scale via a scanning tunnelling microscope (STM) W tip provides a potentially powerful way of building silicon diamondoid structures. In this work, we use quantum-chemical atomistic simulations to explore the feasibility of mechanosynthesis on an hydrogenated Si(111) surface using a STM tip. A sequence of energetically favourable insertion reactions is established leading to stable surface intermediates. This sequence of operations is sufficient to build an indefinitely large volume of diamondoid lattice. The sequence is based solely on two reactants (Si and ) with the overall charge neutrality of the structure maintained. We characterize reaction rates and energy flows and conclude that they are sufficiently fast and simple to make this mechanosynthesis feasible.