Molecular Assembler: Mechanosynthesis Simulator

Target Structure

Manipulator

Tip rigidity 70%

Feedstock temperature 300 K

Assembly speed 1.0×

Build Status

Positioning tip over feedstock…

Atoms placed

0 / 0

Success rate

—

Last bond-acceptance P

—

How it works

This models positional mechanosynthesis — the original "molecular assembler" concept (Drexler, Freitas, Merkle): instead of letting molecules find each other by random diffusion, a rigid tip picks up one feedstock unit at a time and places it directly at a chosen lattice site, forming a covalent bond only if the placement error falls inside a narrow acceptance window.

δ = placement error (pm), sampled ~ N(0, σ_total)
σ_total² = σ_tip² + σ_thermal²
σ_tip = 60·(1 − rigidity)        [mechanical compliance of the tip]
σ_thermal ∝ (T − 100 K)          [Brownian jitter of the feedstock atom]

P(bond) = exp( −δ² / (2·σ_accept²) ),   σ_accept ≈ 35 pm

Tip rigidity — a stiffer cantilever injects less positional noise per attempt (σ_tip shrinks), directly raising the average bond-acceptance probability.
Feedstock temperature — hotter feedstock atoms vibrate more before capture, adding an independent noise term in quadrature (error propagation), which lowers yield even with a perfect tip.
Assembly speed — how often the tip attempts a pick-and-place cycle; it changes throughput, not the per-attempt success probability.
A failed attempt drops the atom back into the feedstock pool and the tip retries the same open site — exactly the retry-until-bonded strategy proposed for real mechanosynthesis tool-tips (e.g. DCB6Ge dimer placement on diamond C(110)).

Two target lattices are offered: a diamond lattice (the sp³ tetrahedral geometry that diamond-mechanosynthesis proposals actually target, because it is mechanically the stiffest known atomic framework) and a simple cubic lattice (an easier six-neighbor geometry, useful for seeing how yield changes when there is more angular tolerance per bond).

Bonded lattice atom Feedstock atom Open target site Manipulator tip

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