1 Mechanosynthesis Ralph C. Merkle Senior Fellow IMM

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1 Mechanosynthesis Ralph C. Merkle Senior Fellow IMM Slide 2 2 www.molecularassembler.com/Nanofactory/ (For further information, links to papers, links to other researchers) Long-term goal: design and ultimately build a diamondoid nanofactory. Web page Slide 3 3 Health, wealth and atoms Slide 4 4 Arranging atoms Flexibility Precision Cost Slide 5 5 Richard Feynman,1959 Theres plenty of room at the bottom Slide 6 6 PropertyDiamonds valueComments Chemical reactivityExtremely low Hardness (kg/mm2)9000CBN: 4500 SiC: 4000 Thermal conductivity (W/cm-K)20Ag: 4.3 Cu: 4.0 Tensile strength (pascals)3.5 x 10 9 (natural)10 11 (theoretical) Compressive strength (pascals)10 11 (natural)5 x 10 11 (theoretical) Band gap (ev)5.5Si: 1.1 GaAs: 1.4 Resistivity (W-cm)10 16 (natural) Density (gm/cm3)3.51 Thermal Expansion Coeff (K-1)0.8 x 10 -6 SiO2: 0.5 x 10 -6 Refractive index2.41 @ 590 nmGlass: 1.4 - 1.8 Coeff. of Friction0.05 (dry)Teflon: 0.05 Source: Crystallume Diamond physical properties What to make Slide 7 7 Hydrocarbon bearing Slide 8 8 Hydrocarbon universal joint Slide 9 9 Rotary to linear NASA Ames Slide 10 10 Bucky gears NASA Ames Slide 11 11 Bearing Slide 12 12 Planetary gear Slide 13 13 Neon pump Slide 14 14 Making diamond today Illustration courtesy of P1 Diamond Inc. Slide 15 15 A synthetic strategy for the synthesis of diamondoid structures Positional assembly (6 degrees of freedom) Highly reactive compounds (radicals, carbenes, etc) Inert environment (vacuum, noble gas) to eliminate side reactions Molecular tools Slide 16 16 Positional assembly Slide 17 17 :mean positional error k: restoring force k b : Boltzmanns constant T:temperature Thermal noise Slide 18 18 :0.02 nm (0.2 ) k: 10 N/m k b : 1.38 x 10 -23 J/K T:300 K Thermal noise Slide 19 19 Annotated bibliography on diamond mechanosynthesis http://www.molecularassembler.com/ Nanofactory/AnnBibDMS.htm Molecular tools (over 50 entries) Slide 20 20 Hydrogen abstraction tool Slide 21 21 Hydrogen abstraction tools Michael Page, Donald W. Brenner, Hydrogen abstraction from a diamond surface: Ab initio quantum chemical study using constrained isobutane as a model, J. Am. Chem. Soc. 113(1991):3270-3274. Charles B. Musgrave, Jason K. Perry, Ralph C. Merkle, William A. Goddard III, Theoretical studies of a hydrogen abstraction tool for nanotechnology, Nanotechnology 2(1991):187-195; http://www.zyvex.com/nanotech/Habs/Habs.html http://www.zyvex.com/nanotech/Habs/Habs.html Xiao Yan Chang, Martin Perry, James Peploski, Donald L. Thompson, Lionel M. Raff, Theoretical studies of hydrogen-abstraction reactions from diamond and diamond-like surfaces, J. Chem. Phys. 99(15 September 1993):4748-4758. Susan B. Sinnott, Richard J. Colton, Carter T. White, Donald W. Brenner, Surface patterning by atomically-controlled chemical forces: molecular dynamics simulations, Surf. Sci. 316(1994):L1055- L1060. D.W. Brenner, S.B. Sinnott, J.A. Harrison, O.A. Shenderova, Simulated engineering of nanostructures, Nanotechnology 7(1996):161-167; http://www.zyvex.com/nanotech/nano4/brennerPaper.pdfhttp://www.zyvex.com/nanotech/nano4/brennerPaper.pdf A. Ricca, C.W. Bauschlicher Jr., J.K. Kang, C.B. Musgrave, Hydrogen abstraction from a diamond (111) surface in a uniform electric field, Surf. Sci. 429(1999):199-205. Berhane Temelso, C. David Sherrill, Ralph C. Merkle, Robert A. Freitas Jr., High-level Ab Initio Studies of Hydrogen Abstraction from Prototype Hydrocarbon Systems, J. Phys. Chem. A 110(28 September 2006):11160-11173; http://pubs.acs.org/cgi-bin/abstract.cgi/jpcafh/2006/110/i38/abs/jp061821e.html (abstract), http://www.MolecularAssembler.com/Papers/TemelsoHAbst.pdf (paper).http://pubs.acs.org/cgi-bin/abstract.cgi/jpcafh/2006/110/i38/abs/jp061821e.htmlhttp://www.MolecularAssembler.com/Papers/TemelsoHAbst.pdf Theoretical bibliography Slide 22 22 Dimer placement Fig. 2. Stepwise retraction simulation of Ge-based tool from clean diamond C(110) surface: (A) initial configuration (C in brown, H in white, Ge in blue); (B) ending configuration after 200 fs at 1.6 above starting position, at 300 K. Peng et al., work done at Zyvex using VASP Slide 23 23 High complexity Over 100 elements in periodic table Therefore over 100 tools Combinatorial explosion in considering reaction sequences Can build almost any structure consistent with physical law Great flexibility in synthesis Making almost anything Slide 24 24 New paper in preparation A Minimal Toolset for Positional Diamond Mechanosynthesis Robert A. Freitas Jr., Ralph C. Merkle Publication Slide 25 25 Three elements: H, C, Ge Limit combinatorial explosion H and C can build almost any rigid structure (diamond, lonsdaleite, graphite, buckytubes, fullerenes, carbyne, organic compounds) Ge provides just enough synthetic flexibility Reduce complexity Slide 26 26 Computational methods 1630 tooltip/workpiece structures 65 Reaction Sequences 328 reaction steps 354 unique pathological side reactions 1321 reported energies consuming 102,188 CPU-hours (using 1-GHz CPUs) Minimal toolset Slide 27 27 Computational methods Gaussian 98 Singlet or doublet geometries optimized with no constrained degrees of freedom using spin-unrestricted Hartree-Fock (UHF) analysis at the B3LYP/3-21G* level of theory Single point energy calculations performed at the B3LYP/6- 311+G(2d,p) level of theory The mean absolute deviation from experiment (MAD) for B3LYP/6-311+G(2d,p) // B3LYP/3-21G* energies is estimated as 0.14 eV for carbon-rich molecules Barriers of 0.4 eV against side reactions in most cases Minimal toolset Slide 28 28 Molecular tools HAbs HDon GM Germylene Methylene HTrans AdamRad DimerP GeRad Slide 29 29 H donation Hydrogen donation onto a C(111) surface radical. -0.61 eV Slide 30 30 H donation Hydrogen donation onto a C(110) surface radical. -0.73 eV Slide 31 31 H donation Hydrogen donation onto a C(111) surface radical. -1.43 eV Slide 32 32 H donation Recharging HAbs (initial approach of first GeRad optimized by Tarasov et al (2007), -0.43 eV with -0.1 eV barrier) Second GeRad abstraction -0.83 eV Slide 33 33 C placement C placement on C(111) using GM tool C radical addition to C radical -3.17 eV (note undesired H abstraction by C radical from sidewall, +0.63 eV barrier) GeRad removal +2.76 eV (note Ge-C bond is soft) HDon hydrogenate C radical -0.70 eV Slide 34 34 C placement 2 nd C placement on C on C(111) C radical addition to C radical -3.12 eV (note undesired H abstraction by C radical from C radical, +0.69 eV barrier) GeRad removal +2.74 eV (note Ge-C bond is soft) HDon hydrogenate C radical -0.65 eV Slide 35 35 C placement C placement on C(100) using GM tool C radical addition to C radical -3.29 eV (note undesired H abstraction by C radical from adjacent dimer, +0.55 eV barrier) GeRad removal +2.66 eV (note Ge-C bond is soft) HDon hydrogenate C radical -0.64 eV Slide 36 36 C placement C placement on adamantane when sidewall site is occupied Slide 37 37 C placement C placement on adjacent site of C(111) surface Slide 38 38 C placement 3 rd C placement on adjacent site of C(111) surface Slide 39 39 C placement C placement on adjacent site of C(100) dimer Slide 40 40 Making tools Building HAbs from DimerP Slide 41 41 Making tools Building HAbs Slide 42 42 Making GM tool Slide 43 43 Making polyyne chain Slide 44 44 Inputs/outputs 100% process closure 9 tools Feedstock: CH 4, C 2 H 2, Ge 2 H 6, and H 2 Flat depassivated diamond and germanium surfaces for C and Ge feedstock presentation Six(?) degree of freedom positional control Slide 45 45 Future work Further analysis of all reactions (higher level of theory, molecular dynamics, etc) Note the volume of work for HAbs alone analysis of all reactions at this depth will require substantial resources Development of directly accessible experimental pathways (the Direct Path) Slide 46 46 Today Overview What we see when we look only at todays experimental work Slide 47 47 Core molecular manufacturing capabilities Today Products Overview The context that theory provides Slide 48 48 Future work We will wander in the desert for a long time without the guidance that computational and theoretical work can provide Slide 49 49 End of talk END OF TALK