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Nanomaterials

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Title: Nanomaterials


1
Nanomaterials
  • Boxuan Gu and David McQuilling

2
What are they?
  • Nano 10-9 or one billionth in size
  • Materials with dimensions and tolerances in the
    range of 100 nm to 0.1 nm
  • Metals, ceramics, polymeric materials, or
    composite materials
  • One nanometer spans 3-5 atoms lined up in a row
  • Human hair is five orders of magnitude larger
    than nanomaterials

3
Nanomaterial Composition
  • Comprised of many different elements such as
    carbons and metals
  • Combinations of elements can make up nanomaterial
    grains such as titanium carbide and zinc sulfide
  • Allows construction of new materials such as C60
    (Bucky Balls or fullerenes) and nanotubes

4
How they are made
  • Clay/polymer nanocomposites can be made by
    subjecting clay to ion exchange and then mixing
    it with polymer melts
  • Fullerenes can be made by vaporizing carbon
    within a gas medium
  • Current carbon fullerenes are in the gaseous
    phase although samples of solid state fullerenes
    have been found in nature

5
Bucky Ball properties
  • Arranged in pentagons and hexagons
  • A one atom thick seperation of two spaces
    inside the ball and outside
  • Highest tensile strength of any known 2D
    structure or element, including cross-section of
    diamonds which have the highest tensile strength
    of all known 3D structures (which is also a
    formation of carbon atoms)
  • Also has the highest packing density of all known
    structures (including diamonds)
  • Impenetrable to all elements under normal
    circumstances, even a helium atom with an energy
    of 5eV (electron Volt)

6
Bucky Ball properties cont.
  • Even though each carbon atom is only bonded with
    three other carbons (they are most happy with
    four bonds) in a fullerene, dangling a single
    carbon atom next to the structure will not affect
    the structure, i.e. the bond made with the
    dangling carbon is not strong enough to break the
    structure of the fullerene
  • No other element has such wonderful properties as
    carbon which allows costs to be relatively cheap
    after all its just carbon and carbon is
    everywhere

7
Buckminsterfullerene uses
  • Due to their extremely resilient and sturdy
    nature bucky balls are debated for use in combat
    armor
  • Bucky balls have been shown to be impervious to
    lasers, allowing for defenses from future
    warfare
  • Bucky balls have also been shown to be useful at
    fighting the HIV virus that leads to AIDS
  • Researchers Kenyan and Wudl found that water
    soluble derivates of C60 inhibit the HIV-1
    protease, the enzyme responsible for the
    development of the virus
  • Elements can be bonded with the bucky ball to
    create more diverse materials including
    superconductors and insulators
  • Can be used to fashion nanotubes

8
Bucky Balls
C240 colliding with C60 at 300 eV (Kinetic energy)
Bucky Ball (C60)
http//www.pa.msu.edu/cmp/csc/simindex.html
9
Nanotube properties
  • Superior stiffness and strength to all other
    materials
  • Extraordinary electric properties
  • Reported to be thermally stable in a vacuum up to
    2800 degrees Centigrade (and we fret over CPU
    temps over 50o C)
  • Capacity to carry an electric current 1000 times
    better than copper wires
  • Twice the thermal conductivity of diamonds
  • Pressing or stretching nanotubes can change their
    electrical properties by changing the quantum
    states of the electrons in the carbon bonds
  • They are either conducting or semi-conducting
    depending on the their structure

10
Nanotube uses
  • Can be used for containers to hold various
    materials on the nano-scale level
  • Due to their exceptional electrical properties,
    nanotubes have a potential for use in everyday
    electronics such as televisions and computers to
    more complex uses like aerospace materials and
    circuits

11
Nanotubes
Switching nanotube-based memory
Carbon based nanotubes
http//www.pa.msu.edu/cmp/csc/simindex.html
12
Applications of Nanotechnology
  • Next-generation computer chips
  • Ultra-high purity materials, enhanced thermal
    conductivity and longer lasting nanocrystalline
    materials
  • Kinetic Energy penetrators (DoD weapon)
  • Nanocrystalline tungsten heavy alloy to replace
    radioactive depleted uranium
  • Better insulation materials
  • Create foam-like structures called aerogels
    from nanocrystalline materials
  • Porous and extremely lightweight, can hold up to
    100 times their weight

13
More applications
  • Improved HDTV and LCD monitors
  • Nanocrystalline selenide, zinc sulfide, cadmium
    sulfide, and lead telluride to replace current
    phosphors
  • Cheaper and more durable
  • Harder and more durable cutting materials
  • Tungsten carbide, tantalum carbide, and titanium
    carbide
  • Much more wear-resistant and corrosion-resistant
    than conventional materials
  • Reduces time needed to manufacture parts, cheaper
    manufacturing

14
Even more applications
  • High power magnets
  • Nanocrystalline yttrium-samarium-cobalt grains
    possess unusually large surface area compared to
    traditional magnet materials
  • Allows for much higher magnetization values
  • Possibility for quieter submarines,
    ultra-sensitive analyzing devices, magnetic
    resonance imaging (MRI) or automobile alternators
    to name a few
  • Pollution clean up materials
  • Engineered to be chemically reactive to carbon
    monoxide and nitrous oxide
  • More efficient pollution controls and cleanup

15
Still more applications
  • Greater fuel efficiency for cars
  • Improved spark plug materials, railplug
  • Stronger bio-based plastics
  • Bio-based plastics made from plant oils lack
    sufficient structural strength to be useful
  • Merge nanomaterials such as clays, fibers and
    tubes with bio-based plastics to enhance strength
    and durability
  • Allows for stronger, more environment friendly
    materials to construct cars, space shuttles and a
    myriad of other products

16
Applications wrapup
  • Higher quality medical implants
  • Current micro-scale implants arent porous enough
    for tissue to penetrate and adapt to
  • Nano-scale materials not only enhance durability
    and strength of implants but also allow tissue
    cells to adapt more readily
  • Home pregnancy tests
  • Current tests such as First Response use gold
    nanoparticles in conjunction with micro-meter
    sized latex particles
  • Derived with antibodies to the human chorionic
    gonadotrophin hormone that is released by
    pregnant women
  • The antibodies react with the hormone in urine
    and clump together and show up pink due to the
    nanoparticles plamson resonance absortion
    qualities

17
Modeling and Simulation of Nanostructured
Materials and Systems
18
Preface
  • Each distinct age in the development of humankind
    has been associated with advances in materials
    technology.
  • Historians have linked key technological and
    societal events with the materials technology
  • that was prevalent during the stone age,
    bronze age, and so forth.

19
Significant events In materials
  • 1665 - Robert Hooke material microstructure
  • 1808 - John Dalton atomic theory
  • 1824 - Portland cement
  • 1839 - Vulcanization
  • 1856 - Large-scale steel production
  • 1869 - Mendeleev and Meyer Periodic Table of
    the Chemical Elements
  • 1886 - Aluminum
  • 1900 - Max Planck . quantum mechanics

20
Cont.
  • 1909 - Bakelite
  • 1921 - A. A. Griffith . fracture strength
  • 1928 - Staudinger polymers (small molecules that
    link to form chains)
  • 1955 - Synthetic diamond
  • 1970 - Optical fibers
  • 1985 - First university initiatives attempt
    computational materials design
  • 1985 - Bucky balls (C60) discovered at Rice
    University
  • 1991 - Carbon nanotubes discovered by Sumio
    Iijima

21
Why we need Computational Materials?
  • Traditionally, research institutions have relied
    on a discipline-oriented approach to material
  • development and design with new materials.
  • It is recognized, however, that within the scope
    of materials and structures research, the breadth
    of length and time scales may range more than 12
    orders of
  • magnitude, and different scientific and
    engineering disciplines are involved at each
    level.

22
  • To help address this wide-ranging
    interdisciplinary research, Computational
    Materials has been formulated with the specific
    goal of exploiting the tremendous physical and
    mechanical properties of new nano-materials by
    understanding materials at atomic, molecular, and
    supramolecular levels.

23
  • Computational Materials at LaRC draws from
    physics and chemistry, but focuses on
    constitutive descriptions of materials that are
    useful in formulating macroscopic models of
    material performance.

24
Benefit of Computational materials
  • First, it encourages a reduced reliance on costly
    trial and error, or serendipity, of the
    Edisonian approach to materials research.
  • Second, it increases the confidence that new
    materials will possess the desired properties
    when scaled up from the laboratory level, so that
    lead-time for the introduction of new
    technologies is reduced.
  • Third, the Computational Materials approach
    lowers the likelihood of conservative or
    compromised designs that might have resulted from
    reliance on less-than-perfect materials.

25
Schematic illustration of relationships between
time and length scales for the multi-scale
simulation methodology.
26
Cont.
  • The starting point is a quantum description of
    materials this is carried forward to an
    atomistic scale for initial model development.
  • Models at this scale are based on molecular
    mechanics or molecular dynamics.

27
Cont.
  • At the next scale, the models can incorporate
    micro-scale features and simplified constitutive
    relationships.
  • Further progress up, the scale leads to the meso
    or in-between levels that rely on combinations of
    micromechanics and wellestablished theories such
    as elasticity.

28
Cont.
  • The last step towards engineering-level
    performance is to move from mechanics of
    materials to structural mechanics by using
    methods that rely on empirical data,constitutive
    models, and fundamental mechanics.

29
Nanostructured Materials
  • The origins of focused research into
    nanostructured materials can be traced back to a
    seminal lecture given by Richard Feynman in
    19591.
  • In this lecture, he proposed an approach to the
    problem of manipulating and controlling things on
    a small scale. The scale he referred to was not
    the microscopic scale that was familiar to
    scientists of the day but the unexplored
    atomistic scale.

30
  • The nanostructured materials based on carbon
    nanotubes and related carbon structures are of
    current interest for much of the materials
    community.
  • More broadly then, nanotechnology presents the
    vision of working at the molecular level, atom by
    atom, to create large structures with
    fundamentally new molecular organization.

31
Simluation methods
32
Atomistic, Molecular Methods
  • The approach taken by the Computational Materials
    is formulation of a set of integrated predictive
    models that bridge the time and length scales
    associated with material behavior from the nano
    through the meso scale.

33
  • At the atomistic or molecular level, the reliance
    is on molecular mechanics,
  • molecular dynamics, and coarse-grained,
    Monte-Carlo simulation.
  • Molecular models encompassing thousands and
    perhaps millions of atoms can be solved by these
    methods and used to predict fundamental,
    molecular level material behavior. The methods
    are both static and dynamic.

34
  • Molecular dynamics simulations generate
    information at the nano-level, including atomic
    positions and velocities.
  • The conversion of this information to macroscopic
    observables such as pressure, energy, heat
    capacities, etc., requires statistical
    mechanics.

35
  • An experiment is usually made on a macroscopic
    sample that contains an extremely large number of
    atoms or molecules, representing an enormous
    number of conformations.
  • In statistical mechanics, averages corresponding
    to experimental measurements are defined in terms
    of ensemble averages.

36
For example
where M is the number of configurations in the
molecular dynamics trajectory and Vi is the
potential energy of each configuration.

37
where M is the number of configurations in the
simulation, N is the number of atoms in the
system, mi is the mass of the particle i and vi
is the velocity of particle i.
To ensure a proper average, a molecular dynamics
simulation must account for a large number of
representative conformations.
38
  • By using Newtons second law to calculate a
    trajectory, one only needs the initial positions
    of the atoms, an initial distribution of
    velocities and the acceleration, which is
    determined by the gradient of the potential
    energy function.
  • The equations of motion are deterministic i.e.,
    the positions and the velocities at time zero
    determine the positions and velocities at all
    other times, t. In some systems, the initial
    positions can be obtained from experimentally
    determined structures.

39
  • In a molecular dynamics simulation, the time
    dependent behavior of the molecular system is
    obtained by integrating Newtons equations of
    motion.
  • The result of the simulation is a time series of
    conformations or the path followed by each atom.

  • Most molecular dynamics simulations are performed
    under conditions of constant number of atoms,
    volume, and energy (N,V,E) or constant number of
    atoms, temperature, and pressure (N,T,P) to
    better simulate experimental conditions.

40
Basic steps in the MD simulation
  • 1. Establish initial coordinates.
  • 2. Minimize the structure.
  • 3. Assign initial velocities.
  • 4. Establish heating dynamics.
  • 5. Perform equilibration dynamics.
  • 6. Rescale the velocities and check if the
    temperature is correct.
  • 7. Perform dynamic analysis of trajectories.

41
Monte Carlo Simulation
  • Although molecular dynamics methods provide the
    kind of detail necessary to resolve molecular
    structure and localized interactions, this
    fidelity comes with a price. Namely, both the
    size and time scales of the model are limited by
    numerical and computational boundaries.

42
  • To help overcome these limitations,coarse-grained
    methods are available that represent molecular
    chains as simpler, bead-spring models.
  • Coarse-grain models are often linked to Monte
    Carlo (MC) simulations to provide a timely
    solution.
  • The MC method is used to simulate stochastic
    events and provide statistical approaches to
    numerical Integration.

43
  • There are three characteristic steps in the MC
    simulation that are given as follows.
  • 1. Translate the physical problem into an
    analogous probabilistic or statistical model.
  • 2. Solve the probabilistic model by a numerical
    sampling experiment.
  • 3. Analyze the resultant data by using
    statistical methods.

44
Continum Methods
  • Despite the importance of understanding the
    molecular structure and nature of materials, at
    some level in the multi-scale analysis the
    behaviour of collections of molecules and atoms
    can be homogenized.

45
  • At this level, the continuum level, the observed
    macroscopic behaviour is explained by
    disregarding the
  • discrete atomistic and molecular structure and
    assuming that the material is continuously
    distributed throughout its volume.
  • The continuum material is assumed to have an
    average density and can be subjected to body
    forces such as gravity and surface forces such as
    the contact between two bodies.

46
  • The continuum can be assumed to obey several
    fundamental laws.
  • The first, continuity, is derived from the
    conservation of mass.
  • The second, equilibrium, is derived from momentum
    considerations and Newtons second law.
  • The third, the moment of momentum principle, is
    based on the model that the time rate of change
    of angular momentum with respect to an arbitrary
    point is equal to the resultant moment.

47
  • These laws provide the basis for the continuum
    model and must be coupled with the appropriate
    constitutive equations and equations of state to
    provide all the equations necessary for solving a
    continuum problem.
  • The state of the continuum system is described by
    several thermodynamic and kinematic state
    variables.
  • The equations of state provide the relationships
    between the non-independent state variables.

48
  • The continuum method relates the deformation of a
    continuous medium to the external forces acting
    on the medium and the resulting internal stress
    and strain.
  • Computational approaches range from simple
    closed-form analytical expressions to
    micromechanics to complex structural mechanics
    calculations basedon beam and shell theory.

49
  • The continuum-mechanics methods rely on
    describing the geometry, (I.e.physical model),
    and must have a constitutive relationship to
    achieve a solution.
  • For a displacement based form of continuum
    solution, the principle of virtual work is
    assumed valid.

50
In general, this is given as
51
where W is the virtual work which is the work
done by imaginary or virtual displacements, is
the strain, is the stress, P is the body force, u
is the virtual displacement, T is the tractions
and F is the point forces. The symbol is the
variational operator designating the virtual
quantity. For a continuum system, a necessary an
d sufficient condition for equilibrium is that
the virtual work done by sum of the external
forces and internal forces vanish for any virtual
displacement.
52
Software for Nanomaterials
53
BOSS-Biochemical and Organic Simulation System
  • The B O S S program performs (a) Monte Carlo (MC)
    statistical mechanics simulations for solutes in
    a periodic solvent box, in a solvent cluster, or
    in a dielectric continuum including the gas
    phase, and (b) standard energy minimizations,
    normal mode analysis, and conformational
    searching.

54
XMakemol
  • XMakemol is a mouse-based program, written using
    the LessTif widget set, for viewing and
    manipulating atomic and other chemical systems.
    It reads XYZ input and renders atoms, bonds and
    hydrogen bonds.

55
Features
  • Animating multiple frame files
  • Interactive measurement of bond lengths, bond
    angles and torsion angles
  • Control over atom/bond sizes
  • Exporting to XPM, Encapsulated PostScript and Fig
    formats
  • Toggling the visibility of groups of atoms
  • Editing the positions of subsets of atoms

56
A water molecule with vectors along the principal
axes

57
As above, with lighting turned off
58
Candidate structure for the H2O(20) global
minimum

59
Buckminster Fullerene
60
Amsterdam Density Functional (ADF) package
  • The Amsterdam Density Functional (ADF) package is
    software for first-principles electronic
    structure calculations. ADF is used by academic
    and industrial researchers worldwide in such
    diverse fields as pharmacochemistry and materials
    science

61
  • It is currently particularly popular in the
    research areas of
  • homogeneous and heterogeneous catalysis
  • inorganic chemistry
  • heavy element chemistry
  • various types of spectroscopy
  • biochemistry

62
ARP/wARP 
ARP/wARP  is a package for automated protein
model building and structure refinement. It is
based on a unified approach to the structure
solution process by combining electron density
interpretation using the concept of the hybrid
model, pattern recognition in an electron density
map and maximum likelihood model parameter
refinement.
63
  • The ARP/wARP suite is under continuous
    development. The present release, Version 6.0,
    can be used in the following ways
  • Automatic tracing of the density map and model
    building. This includes the refinement of MR
    solutions and the improvement of MAD and
    M(S)IR(AS) phases via map interpretation
  • Free atoms density modification
  • Building of the solvent structure

64
Chemsuite - A suite designed for chemistry on
Linux
  • Chemsuite is composed by several program
  • Chem2D A 2D molecular drawer.
  • Molcalc A molecular weight calculator  
  • ChemModel3D Molecular 3D modeler
  • ChemIR An infrared spectra processor.
  • It can read, process, export and print Perkin
    Elmerspectra.
  • ChemNMR 1D NMR Processor
  • ChemMC Monte carlo Simulator and Integrator

65
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66
General Atomic and Molecular Electronic Structure
System (GAMESS)
  • GAMESS is a program for ab initio quantum
    chemistry. Briefly, GAMESS can compute SCF
    wavefunctions ranging from RHF, ROHF, UHF, GVB,
    and MCSCF. Correlation corrections to these SCF
    wavefunctions include Configuration Interaction,
    second order perturbation theory, and
    Coupled-Cluster approaches, as well as the
    Density Functional Theory approximation.

67
Useful site
  • http//www.linuxlinks.com/Software/Scientific/Chem
    istry/
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