Difference between revisions of "Design of crystolecules"

Revision as of 15:54, 12 July 2017

This page is about issues with the design of crystolecules / DMEs.
For a definition of what they are see here: "What are crystolecules DMEs?"

Applicability of 3D FDM printing for Crystolecule Design

Main article: applicability of macro 3D printing for nanomachine prototyping

If certain rules (according to exploratory engineering) are adhered to then cheap FDM 3D printing (FDM ... fused deposition modelling i.e. printing with molten plastic from a nozzle) can be useful to check the workability of mechanical concepts for advanced nano-machines. Non functional models purely for visualization that have all their surface atoms visible and color coded require more expensive full color powder printing.

The author of this Wiki (about) conducts a meta project that aims to build up a collection of 3D-printable 3D-models (mainly in atom aware bulk limit) that will hopefully turn out to be useful in the development and understanding of advanced nanofactories. See main article: The DAPMAT demo project

Some things to take care of

avoid quartz like solid CO₂ or the like

Too much oxygen must not be brought in direct bonding contact with carbon atoms since this may practically represent solid CO₂ which will likely behave like an explosive. The same goes for other combinations that are known to be highly energetic from normal cemistry. Some examples: room temperature solid nitrogen (in sp3 hybridisation), oxygen chains, ...

avoid too high interface pressure in sleeve bearings

If the fit gets too tight the atom "teeth" may jump without energy recuperation and it will work as friction unit instead.

check for too strained spots in auto-generated passivation layers

Concave edges passivated with hydrogen sometimes causes the hydrogen atoms to massively overlap. Sometimes two hydrogens can be replaced by a oxygen bridge but this introduces tension that may detrimentally deform the crystolecule. Alternating with oxygen with its bigger cousin sulfur or nitrogen with phosphor might help in some cases.

Since passivation atoms add thickness it can be tricky to create parts complementary in shape. [todo: collect some tricks here how this can be made easier]

avoid situations where poisonous molecules may be released on thermal or chemical attack

(TODO: elaborate on this)

• Cyanides
• organophosphorus compounds (leave to Wikipedia - please come back again)
• Halogenides
• Small polyaromatic molecules - organic pigments (leave to Wikipedia - please come back again) have usually low toxicity but also low biodegradability - related: color emulation

Controlled breaking can very effectively porotect internal materials from chemical attack.

Regarding molecular dynamics

avoid elements left of the carbon group (at least for now)

Electron deficiency bonds are misrepresented nanoengineer-1's current force field models. A nitrogen atom adjacent to a boron atom embedded in a diamond crystal shouldn't strongly repel each other but instead behave almost like carbon atoms since the boron has the space for the nitrogens excess electron. Since aluminium is to an electron deficient element it is likely to misbehave the same way as boron does in the nanoengineer-1 model. A safe way to go is to not use them yet in crystolecule designs.

Equilibration method

Nanoenginer-1 (TODO: version?) seems to use a rather naive force field equilibration method of just iteratively equilibrating all the atoms one after another and applying the changes all at once (not sure if this is the case - (TODO: check code)) that does not scale well. A self adapting (TODO: add implementation ideas) 6D space Fourier space deformation method might be implementable to speed up equilibration massively. (TODO: IIRC there where news of a new faster equilibration method - find it and link it here)

Related

Intended working environment: vacuum / aggressive medium

At any time the accessible crystolecule structures are given by the available capabilities of Mechanosynthesis.

• Design levels
• Pseudo phase diagram
• Isostructural bending
• The DAPMAT demo project
• Applicability of macro 3D printing for nanomachine prototyping

• Crystolecules can already be designed and analyzed in great detail but they cannot yet be built. This is one area where a theoretical overhang can build up.

External links

• molecular dynamics: (leave to Wikipedia - please come back again)

Software:

• NanoEngineer-1
  Here some active development continues to happen:
  (Umbrella brand: MDS Molecular Dynamics Studio)
  The new focus though seems to go more in the direction of science than engineering.

Situations to avoid or at least to be aware of:

• https://en.wikipedia.org/wiki/Fluxional_molecule
• https://en.wikipedia.org/wiki/Tautomer
• https://en.wikipedia.org/wiki/Fast_ion_conductor
• water exchanges its hydrogen atoms mixing H₂O and D₂O produces HDO - https://en.wikipedia.org/wiki/Heavy_water