Revision as of 12:14, 9 April 2021

This kind of mechanosynthesis:

• is fully positionally constrained
• applies forces and torques

Full positional constraint is a prerequisite for applies forces and torques.

Unnaturality of the process

Force applying mechanosynthesis is a rather unnatural process. Unnatural chemistry so to say.
Some natural enzymes may be able to provide sufficient positional constraint such
that some small forces and torques are involved in bond reconfigurations.
But anything there is minute compared to the magnitude of forces and torques that
will be involved in force applying mechanosynthesis will use.

Where force applying mechanosynthesis will be performed

This would be performed in the molecular mills of future gem-gum factories. For:

• picking molecules up into machine phase
• Tooltip preparation in a tooltip preparation cycle. Making molecules into reactive moieties.
• Final deposition of moieties onto the crystolecules under assembly (under synthesis).

Factors influencing expectable throughput

Factors increase throughput:

• The forces and torques allow to massively speed up chemical reactions.
• The forces and torques make almost all attempts for reaction succeed unlike normal chemistry where its often more the reverse.

Factors decrease throughput:

• Unavoidably fat fingers reduce the number of reaction sides per volume compared to natural chemistry.
• Slow down of machinery speeds at the smallest scales to reduce dynamic friction in the many superlubricating nanoscale bearings.

While decreased spacial reaction site density cancels out with the increased temporal reaction frequency quite a bit
it is still important to keep the individual assembly cells (as in: volume per active reaction site) as small as possible.
This leads to a hard coded standard part factory line manufacturing design as the natural chice for the lowest assembly level.

R&D

Experimental state

There have been successful experiments with silicon, and hydrogen on silicon.
Albeit this was done with non atomically precise tips. And thus still very crude.

Theoretical modelling

Extended simulations have been performed on mechanosynthesis of diamond and other pure carbon compounds (allotropes).
See: Tooltip chemistry

More advanced quantum mechanically accurate simulations are needed compared to
the simulation of molecular machine elements where
often much simpler and more scalable molecular dynamics simulations suffice.

Why forces (and torques) between atoms are rarely mentioned in chemistry and physics

Precisely because this is very difficult to do experimentally. Usually one talks about energies which are much more easily measurable via various forms of spectroscopy.

Even with our current day macroscopic scanning probe microscopy which
provides a direct means for probing such forces this is quite difficult.

• Bond forces can be derived from the changes of energy with bond distance (first spacial derivative)
• Bond Stiffnesses can be derived from the changes of force with bond distance (second spacial derivative)

From the equilibrium bond energy alone (as found in bond dissociation energy tables) bond forces can not be derived.

There are quite good classical (non quantum mechanical) approximation models for forces and torques between. These are used in molecular dynamics simulations.

Related

• The various forms of Mechanosynthesis
• Mechanosynthesis
• Raw materials
• Mechanosynthesis core

External links

• Wikipedia: Bond-dissociation_energy